JP2012230941A - Laser light source device - Google Patents

Abstract

An object of the present invention is to provide a laser light source device that can effectively use the light output of a solid-state laser element excited by a semiconductor laser as the light output of a green laser light source device.
A first reflection member and a wavelength which are provided on a surface to which excitation laser light is input from a semiconductor laser and reflect laser light having a fundamental wavelength and laser light converted by a wavelength conversion element and output. A second reflecting member 46 that transmits the laser beam converted and output by the conversion element 35 and reflects the laser beam having the fundamental wavelength, and the first reflecting member 42 in the laser beam path having the fundamental wavelength. A laser beam phase difference generating means 50 is provided between the second reflecting member 46 and the second reflecting member 46.
[Selection] Figure 7

Description

  The present invention relates to a laser light source device using a semiconductor laser, and more particularly to a laser light source device used for a light source of an image display device.

  In recent years, a technique using a semiconductor laser as a light source of an image display device has attracted attention. This semiconductor laser has better color reproducibility, instantaneous lighting, longer life, and higher efficiency and lower power consumption compared to mercury lamps that have been widely used in image display devices. It has various advantages, such as being able to be made and being easy to miniaturize.

  In the laser light source device used for such an image display device, since there is no high-power semiconductor laser that directly outputs green laser light, the pumping laser light is output from the semiconductor laser, and this pumping laser light is used. A technique is known in which a solid-state laser element is excited to output infrared laser light, and the wavelength of the infrared laser light is converted by a wavelength conversion element to output green laser light (for example, Patent Document 1). reference).

  Further, a ceramic laser having a good temperature characteristic at low cost using ceramic instead of expensive yttrium vanadate (YVO4) as a solid-state laser element is known.

JP 2008-16833 A

  However, in a green laser light source device using a ceramic laser, the ceramic light is used as the solid-state laser element, so that the deflection direction of the laser beam to be output cannot be aligned like the YVO4 laser. That is, there is a problem that the output light power of the ceramic laser has an output light power in an unusable deflection direction that occupies about 50% of the total amount and is not effectively used as a green laser light source device.

  The present invention has been devised to solve such problems of the prior art, and the light output of a solid-state laser element excited by a semiconductor laser is effectively used as the light output of a green laser light source device. It is an object of the present invention to provide a laser light source device that can perform the above-described process.

  In order to solve the above problems, a laser light source device of the present invention includes a semiconductor laser that outputs excitation laser light, and a solid-state laser element that outputs infrared laser light having a fundamental wavelength by the excitation laser light output from the semiconductor laser. A wavelength conversion element that converts the wavelength of the laser light output from the solid-state laser element to ½, and a solid-state laser element that is provided on a surface to which excitation laser light is input from the semiconductor laser and has a fundamental wavelength A first reflecting member that reflects the laser beam and the laser beam that has been converted and output by the wavelength conversion element and the laser beam that has been converted and output by the wavelength conversion element are transmitted and the infrared laser beam having the fundamental wavelength is reflected. A laser beam phase difference generating means is provided between the first reflecting member and the second reflecting member in the laser beam path having the fundamental wavelength and the second reflecting member. wave A phase difference provided to the infrared laser light, characterized in that rotates its polarization direction.

  According to the present invention, the laser beam of the ceramic laser having good temperature characteristics can be easily converted into the green laser beam by attaching the laser beam phase difference generating means in the laser beam path. That is, a part of the ceramic laser beam having a fundamental wavelength of 1064 nm has a polarization direction that cannot be converted by the wavelength conversion element, but all of this light is easily converted into green laser beam having a wavelength of 532 nm by the laser beam phase difference generating means. Accordingly, the light output of the ceramic laser excited by the semiconductor laser can be effectively used as the light output of the green laser light source device.

1 is a schematic configuration diagram of an image display device according to Embodiment 1 of the present invention. Schematic diagram showing the state of laser light in the green laser light source device of Embodiment 1 of the present invention The perspective view of the green laser light source device in Embodiment 1 of this invention The perspective view of the wavelength conversion element in Embodiment 1 of this invention Schematic diagram showing the manufacturing process of the wavelength conversion element in the first embodiment of the present invention. Schematic diagram for explaining the state of laser light when the λ / 4 film is not attached in Embodiment 1 of the present invention Schematic diagram illustrating the state of laser light when the λ / 4 film in the first embodiment of the present invention is attached to the output side of the wavelength conversion element Schematic diagram explaining the situation of laser light when the λ / 4 film in the second embodiment of the present invention is provided on the surface of the concave mirror Schematic diagram explaining the situation of laser light when the λ / 4 film in the third embodiment of the present invention is provided on the input side of the wavelength conversion element Schematic diagram for explaining the situation of laser light when an optical phase difference generator having a birefringent spherical structure in Embodiment 4 of the present invention is provided.

  According to a first aspect of the present invention, there is provided a semiconductor laser that outputs excitation laser light, a solid-state laser element that outputs infrared laser light having a fundamental wavelength by the excitation laser light output from the semiconductor laser, and a solid-state laser element. A wavelength conversion element that converts the wavelength of the output laser light to ½, and a solid-state laser element that is provided on a surface to which excitation laser light is input from a semiconductor laser, and a fundamental wavelength laser light and a wavelength conversion element A first reflecting member that reflects the laser beam converted and output by the laser, and a second reflecting member that transmits the laser beam converted and output by the wavelength conversion element and reflects the infrared laser beam having the fundamental wavelength; And a laser beam phase difference generating means between the first reflecting member and the second reflecting member in the laser beam path having the fundamental wavelength, the laser beam phase difference generating means being an infrared laser beam having a fundamental wavelength. Phase difference The laser light source device is characterized in that its polarization direction is rotated, and the laser light phase difference generating means is installed in the laser light path so that it is in the laser light of a solid-state laser element using a ceramic laser. Light of a solid-state laser device excited by a semiconductor laser is easily converted from a fundamental wavelength laser beam having a wavelength of 1064 nm having a lateral component that is an unnecessary deflection direction into a laser beam having a wavelength of 532 nm having only a longitudinal component. The output can provide a laser light source device that can be effectively used as the light output of the green laser light source device.

  According to a second aspect of the present invention, in the laser light source device according to the first aspect, the laser light phase difference generating means is a material having birefringence, and the laser utilizing the characteristics of birefringence is utilized. A phase difference of light can be easily created, and a thin film can be formed easily by sputtering or the like, and the laser light phase difference generating means is formed of a thin film, thereby reducing the size of the laser light source device. be able to.

  The invention described in claim 3 is characterized in that the laser beam phase difference generating means is a thin film, and the thickness thereof is a thickness that shifts the phase of the infrared laser beam having the fundamental wavelength by π / 2. The laser light source device according to claim 1, wherein a thin film can be easily formed by sputtering or the like, and the thickness of the film is shifted to shift the phase of the infrared laser to rotate the polarization of the laser beam. Can be achieved with a small number of reciprocations of the laser beam.

  The invention according to claim 4 is the laser light source device according to claim 3, wherein the thin film is provided on one end face of the wavelength conversion element or on the solid-state laser element side of the second reflecting member. Therefore, it is not necessary to prepare a separate member to which a thin film that is a laser light phase difference generating means is attached, and it is possible to achieve cost reduction and downsizing of the laser light source device by using necessary constituent members as the laser light source device. it can.

  A fifth aspect of the present invention is the laser light source apparatus according to the second aspect, wherein one surface of the laser light phase difference generating means is a spherical shape, and a component necessary for the laser light source apparatus is provided. The laser beam phase difference generating means is combined with the laser beam phase difference generating means by making one surface of the laser light phase difference generating means spherical so that one concave mirror has the same curvature as the concave mirror. Cost reduction and miniaturization of the light source device can be achieved.

  According to the sixth aspect of the present invention, the semiconductor laser, the solid-state laser element, the wavelength conversion element, the first reflecting member, and the second reflecting member are integrally supported on one base. 6. The laser light source device according to claim 1, wherein a laser of a solid-state laser element using a ceramic laser is provided by attaching a laser beam phase difference generating means in the laser beam path. A fundamental wavelength laser beam having a wavelength component of 1064 nm having a lateral component that is an unnecessary deflection direction in the light is easily converted into a laser beam having a wavelength component of 532 nm having only a longitudinal component, and is excited by a semiconductor laser. The light output of the laser element can provide an inexpensive and small-sized laser light source device that can be used effectively as the light output of the green laser light source device.

  The laser light source device of the present invention will be described below with reference to the drawings. The embodiment described below is a preferred specific example of the present invention, and technically favorable conditions are described. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these conditions.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an image display apparatus according to Embodiment 1 of the present invention. The image display device 1 projects and displays a required image on a screen, and outputs a green laser light source device 2 that outputs green laser light, a red laser light source device 3 that outputs red laser light, and a blue laser light. The blue laser light source device 4 to output, the liquid crystal reflection type spatial light modulator 5 that modulates the laser light from each laser light source device 2 to 4 according to the video signal, and the laser from each laser light source device 2 to 4 A polarization beam splitter 6 that reflects light to irradiate the spatial light modulator 5 and transmits the modulated laser light emitted from the spatial light modulator 5, and polarizes the laser light emitted from each of the laser light source devices 2 to 4. A relay optical system 7 that leads to the beam splitter 6 and a projection optical system 8 that projects the modulated laser light transmitted through the polarization beam splitter 6 onto a screen are provided.

  The image display device 1 displays a color image by a so-called field sequential method. Laser beams of each color are sequentially output from the laser light source devices 2 to 4 in a time-sharing manner, and an image by the laser beam of each color is visually displayed. It is recognized as a color image by the afterimage effect.

  The relay optical system 7 includes collimator lenses 11 to 13 that convert the laser beams of the respective colors emitted from the laser light source devices 2 to 4 into parallel beams, and the laser beams of the respective colors that have passed through the collimator lenses 11 to 13 in a predetermined direction. First and second dichroic mirrors 14 and 15, a diffusion plate 16 for diffusing the laser light guided by the dichroic mirrors 14 and 15, and a field lens for converting the laser light that has passed through the diffusion plate 16 into a convergent laser 17.

  Assuming that the side from which the laser light is emitted from the projection optical system 8 toward the screen S is the front side, the blue laser light is emitted backward from the blue laser light source device 4 and is green with respect to the optical axis of the blue laser light. The green laser beam and the red laser beam are emitted from the green laser light source device 2 and the red laser light source device 3 so that the optical axis of the laser beam and the optical axis of the red laser beam are orthogonal to each other. , And green laser light are guided to the same optical path by the two dichroic mirrors 14 and 15. That is, the blue laser light and the green laser light are guided to the same optical path by the first dichroic mirror 14, and the blue laser light, the green laser light, and the red laser light are guided to the same optical path by the second dichroic mirror 15.

  The first and second dichroic mirrors 14 and 15 are formed with a film for transmitting and reflecting laser light having a predetermined wavelength on the surface, and the first dichroic mirror 14 transmits blue laser light. And reflects the green laser light. The second dichroic mirror 15 transmits red laser light and reflects blue laser light and green laser light.

  Each of these optical members is supported by the casing 21. The housing 21 functions as a radiator that dissipates heat generated by the laser light source devices 2 to 4 and is formed of a material having high thermal conductivity such as aluminum or copper.

  The green laser light source device 2 is attached to an attachment portion 22 formed in the housing 21 in a state of protruding toward the side. The mounting portion 22 is provided in a state of projecting in a direction perpendicular to the side wall portion 24 from a corner portion where the front wall portion 23 and the side wall portion 24 located respectively in front and side of the accommodation space of the relay optical system 7 intersect. ing. The red laser light source device 3 is attached to the outer surface side of the side wall portion 24 while being held by the holder 25. The blue laser light source device 4 is attached to the outer surface side of the front wall portion 23 while being held by the holder 26.

  The red laser light source device 3 and the blue laser light source device 4 are configured by a so-called CAN package, and the optical axis is positioned on the central axis of the can-shaped exterior portion with the laser chip that outputs the laser light supported by the stem. The laser beam is emitted from a glass window provided in the opening of the exterior part. The red laser light source device 3 and the blue laser light source device 4 are fixed to the holders 25 and 26 by, for example, press-fitting into mounting holes 27 and 28 provided in the holders 25 and 26. The heat generated by the laser chips of the blue laser light source device 4 and the red laser light source device 3 is transmitted to the housing 21 through the holders 25 and 26 to be dissipated, and each of the holders 25 and 26 has a thermal conductivity such as aluminum or copper. It is made of a high material.

  The green laser light source device 2 includes a semiconductor laser 31 that outputs excitation laser light, and a condensing lens that condenses the excitation laser light output from the semiconductor laser 31, a FAC (Fast-Axis Collimator) lens 32 and a rod lens 33. A solid-state laser element 34 that is excited by the excitation laser beam and outputs a basic laser beam (infrared laser beam), and a wavelength that converts the wavelength of the basic laser beam and outputs a half-wavelength laser beam (green laser beam) A conversion element 35, a concave mirror 36 that forms a resonator together with the solid-state laser element 34, a glass cover 37 that prevents leakage of excitation laser light and fundamental wavelength laser light, a base 38 that supports each part, and each part A cover body 39 is provided.

  The green laser light source device 2 is fixed by attaching a base 38 to the mounting portion 22 of the housing 21, and a required width (for example, 0.5 mm) between the green laser light source device 2 and the side wall portion 24 of the housing 21. The following gaps are formed. This makes it difficult for the heat of the green laser light source device 2 to be transmitted to the red laser light source device 3, suppresses the temperature rise of the red laser light source device 3, and allows the red laser light source device 3 with poor temperature characteristics to operate stably. Can do. Further, in order to secure a required optical axis adjustment allowance (for example, about 0.3 mm) of the red laser light source device 3, a required width (for example, 0.3 mm or more) is provided between the green laser light source device 2 and the red laser light source device 3. ) Is provided.

  FIG. 2 is a schematic diagram showing a state of laser light in the green laser light source device 2 according to Embodiment 1 of the present invention. The laser chip 41 of the semiconductor laser 31 outputs excitation laser light having a wavelength of 808 nm. The FAC lens 32 reduces the spread of the first axis of laser light (a direction orthogonal to the optical axis direction and along the drawing sheet). The rod lens 33 reduces the spread of the slow axis of laser light (in the direction orthogonal to the drawing sheet).

  The solid-state laser element 34 is a polycrystal produced using a so-called ceramic manufacturing method, and is excited by a pumping laser beam having a wavelength of 808 nm that has passed through the rod lens 33 to output a fundamental wavelength laser beam having a wavelength of 1064 nm. This solid-state laser element 34 uses yttrium aluminum garnet having a high linear light transmittance. This yttrium aluminum garnet has a cubic crystal structure, so there is no birefringence and no light scattering at the crystal interface. Used as a thing. The ceramic laser of the solid state laser element 34 is known as an inexpensive laser.

  A surface of the solid-state laser element 34 facing the rod lens 33 is provided as a first reflecting member having an antireflection function for the excitation laser beam having a wavelength of 808 nm and a high reflection function for the fundamental wavelength laser beam having a wavelength of 1064 nm. A functioning film 42 is formed.

  A film 43 having a function of preventing reflection of the fundamental wavelength laser beam having a wavelength of 1064 nm is formed on the surface of the solid-state laser element 34 facing the wavelength conversion element 35.

  The wavelength conversion element 35 is a so-called SHG (Second Harmonics Generation) element, and only has a wavelength of light having a longitudinal polarization of a fundamental wavelength laser beam (infrared laser beam) having a wavelength of 1064 nm output from the solid-state laser element 34. A half-wavelength laser beam (green laser beam) having a longitudinal polarization with a wavelength of 532 nm is generated by conversion.

  A film 44 having an antireflection function for the fundamental wavelength laser beam having a wavelength of 1064 nm and a high reflection function for the half wavelength laser beam having a wavelength of 532 nm is formed on the surface of the wavelength conversion element 35 facing the solid laser element 34. ing.

  A film 45 having an antireflection function for the fundamental wavelength laser beam having a wavelength of 1064 nm and the half wavelength laser beam having a wavelength of 532 nm is formed on the surface of the wavelength conversion element 35 facing the concave mirror 36.

  Furthermore, on the surface of the film 45, a so-called λ / 4 film 50 in which the difference in optical distance between the longitudinal polarization of 1064 nm, which is the fundamental wavelength, and the lateral polarization is λ / 4 and the phase difference is π / 2. (The details of the function of this film will be described later). Note that the layer order of the film 45 and the λ / 4 film 50 may be switched. That is, a configuration in which the λ / 4 film 50 is first formed on the surface of the wavelength conversion element 35 facing the concave mirror 36 and then the film 45 is formed. This λ / 4 film 50 has a fundamental wavelength by depositing lithium niobate, potassium niobate or ZTO (Zinc Tin Oxide) having birefringence on the surface of the wavelength conversion element 35 or film 45 by sputtering or the like. It is made by forming a thin film having a thickness that forms a ¼ phase difference of 1064 nm.

  Note that the thickness of the λ / 4 film 50 depends on the material to be formed. In other words, it is not necessary to increase the film thickness in the case of a material that is easy to add a phase difference (high birefringence), and the film thickness is not required in the case of a material that is difficult to add a phase difference (small birefringence). It needs to be thick enough. In the first embodiment, the material of the λ / 4 film 50 is lithium niobate, the film thickness is about 1.9 μm, the optical path length difference between the vertical and horizontal polarizations is 266 nm, and λ / 4 The film 50 acts as a λ / 4 layer.

  The concave mirror 36 has a concave surface on the side facing the wavelength conversion element 35. The concave surface has a function of high reflection for the fundamental wavelength laser beam having a wavelength of 1064 nm and a function for preventing reflection of the half wavelength laser beam having a wavelength of 532 nm. The film | membrane 46 which functions as a 2nd reflection member provided with these is formed. Thereby, the fundamental wavelength laser beam having a wavelength of 1064 nm resonates and is amplified between the film 42 of the solid-state laser element 34 and the film 46 of the concave mirror 36.

  The curvature R of the concave mirror 36 is obtained from satisfying the resonance mode stability condition of the resonator and forming a necessary beam diameter in the resonator, and the wavelength, beam diameter, and resonator interval in the resonator. In the first embodiment, the curvature R is set to 20 mm.

  In the wavelength conversion element 35, a part of the fundamental wavelength laser light having a wavelength of 1064 nm incident from the solid-state laser element 34 is converted into a half-wavelength laser light having a wavelength of 532 nm, and the fundamental wavelength of 1064 nm that has passed through the wavelength conversion element 35 without being converted is converted. The wavelength laser light is reflected by the concave mirror 36 and is incident on the wavelength conversion element 35 again, and is converted into a half-wavelength laser light having a wavelength of 532 nm. The half-wavelength laser light having a wavelength of 532 nm is reflected by the film 44 of the wavelength conversion element 35 and is output from the wavelength conversion element 35.

  Here, the laser beam B1 that is input from the solid-state laser element 34 to the wavelength conversion element 35, wavelength-converted by the wavelength conversion element 35, and output from the wavelength conversion element 35, and once reflected by the concave mirror 36 are wavelength-converted. In a state where the laser beam B2 input to the element 35 and reflected by the film 44 and output from the wavelength conversion element 35 overlaps with each other, the half-wavelength laser light having a wavelength of 532 nm and the fundamental wavelength laser light having a wavelength of 1064 nm interfere with each other. Cause output to drop.

  Therefore, here, the wavelength conversion element 35 is inclined with respect to the optical axis direction so that the laser light beams B1 and B2 do not overlap each other by the refraction action at the input surface 35a and the output surface 35b, so that the wavelength is 532 nm. Thus, interference between the half-wavelength laser beam and the fundamental wavelength laser beam having a wavelength of 1064 nm is prevented, so that a reduction in output can be avoided.

  The glass cover 37 shown in FIG. 1 is formed with a film that does not transmit these laser beams in order to prevent the excitation laser beam having a wavelength of 808 nm and the fundamental wavelength laser beam having a wavelength of 1064 nm from leaking to the outside. ing.

  FIG. 3 is a perspective view of the green laser light source device 2 according to Embodiment 1 of the present invention.

  As shown in FIG. 3, the semiconductor laser 31, the FAC lens 32, the rod lens 33, the solid state laser element 34, the wavelength conversion element 35, and the concave mirror 36 are integrally supported by a base 38. The bottom surface 51 of the base 38 is parallel to the optical axis direction. Here, the direction orthogonal to the bottom surface 51 of the base 38 is defined as the height direction, and the direction orthogonal to the height direction and the optical axis direction is defined as the width direction. In addition, the side close to the bottom surface 51 of the base 38 will be described below, and the side opposite to the bottom surface 51 will be described above, but this does not necessarily coincide with the vertical direction of the actual apparatus.

  The semiconductor laser 31 is obtained by mounting a laser chip 41 that outputs laser light on a mount member 52. The laser chip 41 has a long strip shape in the optical axis direction, and is fixed to a substantially central position in the width direction of one surface of the plate-shaped mount member 52 with the light output surface facing the FAC lens 32 side. Yes. The semiconductor laser 31 is fixed to the base 38 via an attachment member 53. The mounting member 53 is formed of a metal having high thermal conductivity such as copper or aluminum, and thereby heat generated by the laser chip 41 is transmitted to the base 38 and can be dissipated.

  The FAC lens 32 and the rod lens 33 are held by a condenser lens holder 54. The condenser lens holder 54 is supported by a support portion 55 formed integrally with the base 38. The condensing lens holder 54 is coupled to the support portion 55 so as to be movable in the optical axis direction, whereby the positions of the condensing lens holder 54, that is, the FAC lens 32 and the rod lens 33 are adjusted in the optical axis direction. . The FAC lens 32 and the rod lens 33 are fixed to the condenser lens holder 54 with an adhesive before the position adjustment work, and after the position adjustment work, the condenser lens holder 54 and the support portion 55 are fixed to each other with an adhesive. . The solid-state laser element 34 is supported by a solid-state laser element support portion 56 formed integrally with the base 38.

  The wavelength conversion element 35 is held by a wavelength conversion element holder 58. The wavelength conversion element holder 58 is movable in the width direction with respect to the base 38 so that the position of the wavelength conversion element 35 in the width direction and the inclination angle with respect to the optical axis direction can be adjusted. It is provided so as to be rotatable around an axis substantially orthogonal to the direction. The wavelength conversion element 35 is fixed to the wavelength conversion element holder 58 with an adhesive before the position adjustment work, and after the position adjustment work, the wavelength conversion element holder 58 and the base 38 are fixed to each other with an adhesive. The concave mirror 36 is supported by a concave mirror support portion 61 formed integrally with the base 38. Thereby, the optical axis of the laser beam output from the semiconductor laser 31 and the optical axis of the FAC lens 32, the rod lens 33, the solid-state laser element 34, and the wavelength conversion element 35 can be easily adjusted, and a high output green laser beam can be obtained. Can be output.

  FIG. 4 is a perspective view of the wavelength conversion element according to Embodiment 1 of the present invention. FIG. 5 is a schematic diagram showing a manufacturing process of the wavelength conversion element in the first embodiment of the present invention.

  As shown in FIG. 4, the wavelength conversion element 35 has a substantially rectangular parallelepiped shape, and includes a periodic polarization inversion structure in which polarization inversion regions 71 and non-polarization inversion regions 72 are alternately formed in a ferroelectric crystal. The fundamental wavelength laser light is incident in the polarization inversion period direction (the arrangement direction of the polarization inversion regions 71). As a result, it is possible to obtain a laser beam having a double frequency, that is, a half wavelength, by the second harmonic generation of incident light by quasi phase matching. As the ferroelectric crystal, for example, LN (lithium niobate) added with MgO is used.

  In order to form a periodic domain-inverted structure, an electric field in the direction opposite to the polarization direction is applied to the unipolar ferroelectric crystal using the periodic electrode 73 and the counter electrode 74. As a result, the polarization direction of the portion corresponding to the periodic electrode 73 is reversed, and the polarization inversion region 71 is formed in a wedge shape from the periodic electrode 73 toward the counter electrode 74.

  Actually, the wavelength conversion element 35 is manufactured by the process shown in FIG. First, an electrode thin film is laminated on a wafer 75 made of a ferroelectric crystal, and then electrode patterns of a periodic electrode and a counter electrode are formed by photolithography and etching. Next, the substrate 76 is cut out from the wafer 75 on which the electrode pattern is formed, and further cut into an appropriate size. A polarization inversion process is performed on the strip-shaped stack 77 obtained in this manner by applying a voltage using an electrode to form a polarization inversion structure in the stack 77. Further, the end faces 78 and 79 of the stack 77 which become the input face 35a and the output face 35b of the wavelength conversion element 35 are optically polished. Then, a chip to be one wavelength conversion element 35 is cut out from the stack 77.

  Since optical polishing is performed at the stage of the stack 77 having a relatively large size in this way, the stack 77 can be reliably positioned and optical polishing can be performed, whereby the flatness and parallelism of the input surface 35a and the output surface 35b can be achieved. The degree can be ensured with high accuracy.

  Further, in the wavelength conversion element 35 manufactured in this way, only the input surface 35a and the output surface 35b have a high degree of flatness and parallelism by precise polishing, but the top surface 35e and the bottom surface 35f are It is a cut surface at the time of cutting out from the stack 77, and the side surfaces 35c and 35d are both front and back surfaces of the wafer 75, and manufacturing errors remain. For this reason, with respect to the side surfaces 35c, 35d, the top surface 35e, and the bottom surface 35f, the perpendicularity to the input surface 35a and the output surface 35b and the parallelism between the opposing surfaces are not ensured.

  As shown in FIG. 4, the domain-inverted region 71 has a wedge shape whose thickness gradually decreases along the depth direction, and wavelength conversion is performed in the depth direction of the domain-inverted region 71 with respect to incident laser light. By moving the element 35, the ratio between the domain-inverted region 71 and the non-domain-inverted region 72 located on the optical path of the laser light changes, and the wavelength conversion efficiency changes accordingly. Therefore, the position of the wavelength conversion element 35 with respect to the optical axis of the laser beam is adjusted so that the wavelength conversion efficiency is maximized, that is, the output of the laser beam is maximized.

  Next, the function of the λ / 4 film 50 will be described in detail with reference to FIGS. 6 and 7. FIG. 6 is a schematic diagram for explaining the state of the laser beam when the λ / 4 film is not attached in the first embodiment of the present invention. FIG. 7 is a schematic diagram for explaining the state of the laser light when the λ / 4 film in the first embodiment of the present invention is attached to the output side of the wavelength conversion element.

  First, the state of the laser beam when the λ / 4 film 50 is not attached will be described with reference to FIG. The semiconductor laser 31 outputs excitation laser light having a wavelength of 808 nm. Since the polarization direction of the excitation laser beam is a semiconductor laser, it has only one direction of the vertical component (the arrow direction indicating the top and bottom in FIG. 6) (STEP 1).

  The excitation laser light having a wavelength of 808 nm is input to the solid-state laser element 34 which is a ceramic laser via the FAC lens 32 and the rod lens 33 (STEP 2).

  When the excitation laser beam is input to the solid-state laser element 34, the excitation laser beam is excited by the excitation laser beam having a wavelength of 808 nm and outputs a fundamental wavelength laser beam having a wavelength of 1064 nm. Since the solid-state laser element 34 is made of ceramic in the fundamental wavelength laser light having a wavelength of 1064 nm, the polarization direction of the fundamental wavelength laser light includes both a vertical component and a horizontal component (STEP 3).

  Next, when the fundamental wavelength laser light having a wavelength of 1064 nm output from the solid-state laser element 34 is input to the wavelength conversion element 35, only the longitudinal component of the fundamental wavelength laser light is transmitted in the longitudinal direction by the wavelength conversion element 35. The wavelength is converted into a laser beam (green) having a wavelength of 532 nm having only components, and output. On the other hand, the lateral component of the fundamental wavelength laser beam passes through the wavelength conversion element 35 as it is as the lateral component of the fundamental wavelength laser beam having a wavelength of 1064 nm without being wavelength-converted (STEP 4).

When the laser beam having a wavelength of 532 nm having only the vertical component and the fundamental wavelength laser beam having a wavelength of 1064 nm having the horizontal component reach the concave mirror 36, the laser beam has only the vertical component due to the function of the film 46 described above. Laser light having a wavelength of 532 nm is transmitted and irradiated from the green laser light source device 2. On the other hand, a fundamental wavelength laser beam having a wavelength of 1064 nm having a horizontal component is reflected by the film 46 and returns to the wavelength conversion element 35 and the solid-state laser element 34 side (STEP 5).

  Then, a fundamental wavelength laser beam having a wavelength of 1064 nm having a lateral component passes through the wavelength conversion element 35 and the solid state laser element 34 as it is, is reflected by the above-described film 42 at the end of the solid state laser element 34, and is again solid state laser It returns to the direction of the element 34, the wavelength conversion element 35, and the concave mirror 36 (STEP 6).

  That is, the fundamental wavelength laser beam having a wavelength of 1064 nm having a horizontal component repeats the above-described steps, and cannot be used effectively as irradiation light of the green laser light source device 2.

  Accordingly, the state of the laser beam when the λ / 4 film 50 according to the first embodiment of the present invention is attached to the output side of the wavelength conversion element 35 will be described with reference to FIG. Note that the same STEP number is assigned to the STEP number in the same situation as in FIG.

  The semiconductor laser 31 outputs excitation laser light having a wavelength of 808 nm. Since the excitation laser beam is a semiconductor laser, it has only one longitudinal component (STEP 1).

  The excitation laser light having a wavelength of 808 nm is input to the solid-state laser element 34 which is a ceramic laser via the FAC lens 32 and the rod lens 33 (STEP 2).

  When the excitation laser beam is input to the solid-state laser element 34, the excitation laser beam is excited by the excitation laser beam having a wavelength of 808 nm and outputs a fundamental wavelength laser beam having a wavelength of 1064 nm. Since the solid-state laser element 34 is made of ceramic in the fundamental wavelength laser light having a wavelength of 1064 nm, the polarization direction of the fundamental wavelength laser light includes both a vertical component and a horizontal component (STEP 3).

  Next, when the fundamental wavelength laser light having a wavelength of 1064 nm output from the solid-state laser element 34 is input to the wavelength conversion element 35, only the longitudinal component of the fundamental wavelength laser light is transmitted in the longitudinal direction by the wavelength conversion element 35. The wavelength is converted into a laser beam (green) having a wavelength of 532 nm having only components, and output. On the other hand, the lateral component of the fundamental wavelength laser beam passes through the wavelength conversion element 35 as it is as the lateral component of the fundamental wavelength laser beam having a wavelength of 1064 nm without being wavelength-converted (STEP 4).

  Subsequently, when the laser light of each wavelength output from the wavelength conversion element 35 passes through the λ / 4 film 50 at the end of the wavelength conversion element 35, the laser light of wavelength 532 nm having only the vertical component remains as it is. Passes without changing state. On the other hand, the fundamental wavelength laser beam having a wavelength of 1064 nm having only the lateral component is shifted in the clockwise direction (circularly polarized state) by shifting its phase by π / 2. That is, the polarization direction of the laser beam rotates clockwise about the optical axis (STEP 7).

  When a laser beam having a wavelength of 532 nm having only a vertical component and a fundamental wavelength laser beam having a wavelength of 1064 nm having clockwise polarization reach the concave mirror 36, the function of the film 46 causes a wavelength of 532 nm having only a vertical component. The laser beam is transmitted and irradiated from the green laser light source device 2. On the other hand, the fundamental wavelength laser beam having a wavelength of 1064 nm having clockwise polarization is reflected by the film 46 and returns to the λ / 4 film 50, the wavelength conversion element 35, and the solid-state laser element 34 side (STEP 8).

  Then, when the fundamental wavelength laser beam having the wavelength of 1064 nm and having the clockwise polarization reflected by the film 46 of the concave mirror 36 passes through the λ / 4 film 50 at the end of the wavelength conversion element 35 again, the phase thereof is further increased by π / The fundamental wavelength laser beam having a wavelength of 1064 nm having only a vertical component shifted by two is obtained. It can be converted into a laser beam having a polarized light having only a vertical component only by passing through the λ / 4 film 50 twice (STEP 9).

  Subsequently, the fundamental wavelength laser beam having a wavelength of 1064 nm having only the vertical component output from the λ / 4 film 50 is wavelength-converted by the wavelength conversion element 35 into a laser beam having a wavelength of 532 nm having only the vertical component. (STEP 10).

  Then, the laser beam having a wavelength of 532 nm having only the vertical component is reflected by the film 42 at the end of the solid-state laser element 34 and returns again in the direction of the solid-state laser element 34, the wavelength conversion element 35 and the concave mirror 36. (STEP 11).

  Laser light having a wavelength of 532 nm and having only a component in the vertical direction is irradiated from the green laser light source device 2 through the solid-state laser element 34, the wavelength conversion element 35, and the concave mirror 36.

  That is, by attaching the λ / 4 film 50 to the output side of the wavelength conversion element 35 in the laser beam path, the lateral direction which is an unnecessary deflection direction in the laser beam of the solid-state laser element 34 using the ceramic laser. The fundamental wavelength laser beam having a wavelength of 1064 nm having a component is easily converted into a laser beam having a wavelength of 532 nm having only a longitudinal component, and the light output of the solid-state laser element 34 excited by the semiconductor laser 31 is the light of the green laser light source device. Can be used effectively as output.

  In the first embodiment, it is described that when the horizontally polarized light passes through the λ / 4 film 50, the horizontally polarized light turns clockwise and then becomes vertically polarized. However, the rotation direction is not uniquely determined. In the configuration of the λ / 4 film 50, there is a case where the polarization is changed from laterally polarized light to counterclockwise polarized light and then vertically polarized light. The same effect can be exhibited in either polarization direction.

(Embodiment 2)
A second embodiment of the λ / 4 film 50 will be described with reference to FIG. Here, members having the same configuration and function as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 8 is a schematic diagram for explaining the situation of laser light when the λ / 4 film in the second embodiment of the present invention is provided on the surface of the concave mirror.

  The difference between the second embodiment and the first embodiment is the position where the λ / 4 film 50 is formed. That is, the λ / 4 film 50 made by the film forming method described in the first embodiment is provided on the concave mirror 36. Hereinafter, this different point will be described in detail.

  First, the film configuration of the surface of the concave mirror 36 on which the λ / 4 film 50 is formed will be briefly described. First, a film 46 is formed on the concave surface of the concave mirror 36. This film 46 is a film having a high reflection function for a fundamental wavelength laser beam having a wavelength of 1064 nm and an antireflection function for a half wavelength laser beam having a wavelength of 532 nm. A λ / 4 film 50 according to the second embodiment is formed on the surface of the film 46.

  From STEP 1 to STEP 4 of the second embodiment, the state of the laser beam is the same as that of the first embodiment.

  The laser beam having a wavelength of 532 nm and having only the vertical component output from the wavelength conversion element 35 passes through the λ / 4 film 50 and the film 46 on the concave mirror 36 as they are, and is irradiated from the green laser light source device 2. The

  On the other hand, when a fundamental wavelength laser beam having a wavelength of 1064 nm having only a lateral component is input to the concave mirror 36, the phase is shifted by π / 2 at the λ / 4 film 50 first, and then the film 46 is polarized clockwise. And is again passed through the λ / 4 film 50, and the phase thereof is further shifted by π / 2 to become a fundamental wavelength laser beam having a wavelength of 1064 nm having only a longitudinal component.

  In other words, the fundamental wavelength laser beam having a wavelength of 1064 nm having only a horizontal component has a wavelength of 1064 nm having only a vertical component by continuously passing through the λ / 4 film 50 formed on the surface of the concave mirror 36 twice. It becomes laser light and returns to the wavelength conversion element 35 and the solid-state laser element 34 side (STEP 12).

  Subsequently, the fundamental wavelength laser beam having a wavelength of 1064 nm having only the vertical component reflected from the concave mirror 36 is converted into a laser beam having a wavelength of 532 nm having only the vertical component by the wavelength conversion element 35 and is output ( (Step 10).

  Then, the laser beam having a wavelength of 532 nm having only the vertical component is reflected by the film 42 at the end of the solid-state laser element 34 and returns again in the direction of the solid-state laser element 34, the wavelength conversion element 35, and the concave mirror 36. (STEP 11).

  Laser light having a wavelength of 532 nm and having only a component in the vertical direction is irradiated from the green laser light source device 2 through the solid-state laser element 34, the wavelength conversion element 35, and the concave mirror 36.

  That is, by mounting the λ / 4 film 50 on the concave surface of the concave mirror 36 in the laser beam path, a lateral component that is an unnecessary deflection direction in the laser beam of the solid-state laser element 34 using the ceramic laser. The fundamental wavelength laser beam having a wavelength of 1064 nm having the above-mentioned wavelength is easily converted into a laser beam having a wavelength of 532 nm having only a vertical component, and the light output of the solid-state laser element 34 excited by the semiconductor laser 31 is the light output of the green laser light source device. Can be used effectively as

(Embodiment 3)
A third embodiment of the λ / 4 film 50 will be described with reference to FIG. Here, members having the same configuration and function as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 9 is a schematic diagram for explaining the state of laser light when the λ / 4 film in the third embodiment of the present invention is provided on the input side of the wavelength conversion element.

  The difference between the third embodiment and the first embodiment is the position where the λ / 4 film 50 is formed. That is, the λ / 4 film 50 made by the film forming method described in the first embodiment is provided on the input side of the wavelength conversion element 35. Hereinafter, this different point will be described in detail.

  From STEP 1 to STEP 3 of the third embodiment, the state of the laser beam is the same as that of the first embodiment.

  Even if a fundamental wavelength laser beam having a wavelength of 1064 nm including both polarization directions in the longitudinal direction and the transverse direction is input to the λ / 4 film 50 provided on the input side of the wavelength conversion element 35, all polarization directions Is shifted clockwise by a phase of π / 2, but eventually becomes a fundamental wavelength laser beam having a wavelength of 1064 nm including both the vertical and horizontal polarization directions (STEP 13).

  Next, when a fundamental wavelength laser beam having a wavelength of 1064 nm including both longitudinal and lateral polarization directions is input to the wavelength conversion element 35, only the longitudinal component of the fundamental wavelength laser beam has a wavelength. The conversion element 35 converts the wavelength into a laser beam (green) having a wavelength of 532 nm having only a vertical component and outputs the laser beam. On the other hand, the lateral component of the fundamental wavelength laser beam passes through the wavelength conversion element 35 as it is as the lateral component of the fundamental wavelength laser beam having a wavelength of 1064 nm without being wavelength-converted (STEP 4).

  When the laser beam having a wavelength of 532 nm having only the vertical component and the fundamental wavelength laser beam having a wavelength of 1064 nm having only the horizontal component reach the concave mirror 36, the wavelength having only the vertical component is obtained by the function of the film 46. The laser beam of 532 nm is transmitted and irradiated from the green laser light source device 2. On the other hand, a fundamental wavelength laser beam having a wavelength of 1064 nm having only a lateral component is reflected by the film 46 and returns to the wavelength conversion element 35, the λ / 4 film 50, and the solid-state laser element 34 side (STEP 14).

  Then, since the fundamental wavelength laser beam having a wavelength of 1064 nm having only the lateral component reflected by the film 46 of the concave mirror 36 has only the lateral component, it passes through the wavelength conversion element 35 again (STEP 15).

  Subsequently, when laser light having a fundamental wavelength of 1064 nm having only a lateral component output from the wavelength conversion element 35 passes through the λ / 4 film 50 at the end of the wavelength conversion element 35, only the lateral component is present. The fundamental wavelength laser beam having a wavelength of 1064 nm has a phase shifted by π / 2 and is in a state of polarization clockwise (STEP 16).

  Then, the fundamental wavelength laser beam having a wavelength of 1064 nm having clockwise polarization passes through the solid-state laser element 34 as it is, is reflected by the above-described film 42 at the end of the solid-state laser element 34, passes through the solid-state laser element 34 again, It goes to the λ / 4 film 50 at the end of the wavelength conversion element 35 (STEP 17).

  Then, when the fundamental wavelength laser light having a wavelength of 1064 nm having clockwise polarization passes again through the λ / 4 film 50 at the end of the wavelength conversion element 35, the phase is further shifted by π / 2 and has only the component in the vertical direction. The laser light has a fundamental wavelength of 1064 nm (STEP 18).

  Subsequently, the fundamental wavelength laser beam having a wavelength of 1064 nm having only the vertical component output from the λ / 4 film 50 is wavelength-converted by the wavelength conversion element 35 into a laser beam having a wavelength of 532 nm having only the vertical component. The The wavelength-converted laser beam having a wavelength of 532 nm having only the longitudinal component is irradiated from the green laser light source device 2 through the concave mirror 36 (STEP 19).

  That is, by attaching the λ / 4 film 50 to the incident side of the wavelength conversion element 35 in the laser beam path, a lateral direction that is an unnecessary deflection direction in the laser beam of the solid-state laser element 34 using the ceramic laser is obtained. The fundamental wavelength laser beam having a wavelength of 1064 nm having a component is easily converted into a laser beam having a wavelength of 532 nm having only a longitudinal component, and the light output of the solid-state laser element 34 excited by the semiconductor laser 31 is the light of the green laser light source device. Can be used effectively as output.

(Embodiment 4)
Embodiment 4 provided with the optical phase difference generator 80 will be described with reference to FIG. Here, members having the same configuration and function as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 10 is a schematic diagram for explaining the situation of laser light when an optical phase difference generator having a birefringent spherical structure in Embodiment 4 of the present invention is provided.

  The difference between the fourth embodiment and the first embodiment is that an optical phase difference generator 80 having one spherical surface is provided instead of the λ / 4 film 50 (see FIG. 7). Hereinafter, this different point will be described.

  First, the configuration of the optical phase difference generator 80 will be briefly described. The optical phase difference generator 80 is made of the birefringent material described above, and one surface on the laser optical path is a spherical surface. The spherical shape has the curvature of the concave surface of the concave mirror 36 (see FIG. 6) described above. If the curved surface of the optical phase difference generator 80 has this curvature, it also serves as the concave mirror 36 by forming a reflective film having the function of the film 46 (see FIG. 6) on the curved surface of the optical phase difference generator 80. The concave mirror 36 can also be removed, and downsizing and cost reduction can be achieved.

  The difference from the first to third embodiments described above is that the phase is gradually changed every time the fundamental wavelength laser beam having a wavelength component of 1064 nm passes through the optical phase difference generator 80 having a birefringent spherical structure. A fundamental wavelength laser beam having a wavelength of 1064 nm having only a vertical component is generated by shifting, and the wavelength conversion element 35 can convert the laser beam to a wavelength of 532 nm having only a vertical component (STEP 20).

  That is, a fundamental wavelength laser beam having a wavelength of 1064 nm having a horizontal component is reciprocated between the film 42 and the film 46 many times, and gradually converted into a laser beam having a wavelength of 532 nm having only a vertical component. Irradiated from the laser light source device 2. Thus, the fundamental wavelength laser beam having a wavelength component of 1064 nm having a lateral component which is an unnecessary deflection direction in the laser beam of the solid-state laser element 34 using the ceramic laser has a wavelength component of 532 nm having only a longitudinal component. The light output of the solid state laser element 34 that is easily converted into laser light and excited by the semiconductor laser 31 can be effectively used as the light output of the green laser light source device.

  As described above, a low-cost ceramic laser with good temperature characteristics is used for a laser light source device, and a thin film or a member capable of having a different phase delay amount with respect to the polarization state of light is provided in the laser light path. Thus, a fundamental wavelength laser beam having a wavelength of 1064 nm having a lateral component which is an unnecessary deflection direction in a laser beam of a solid-state laser element using a ceramic laser is a laser beam having a wavelength of 532 nm having only a longitudinal component. The light output of the solid-state laser element that is easily converted into the light source and excited by the semiconductor laser can be effectively used as the light output of the green laser light source device. Further, by using the configuration of the present invention for the laser light source device, the laser light source device can be provided at a low cost and with high reliability.

  The laser light source device according to the present invention has an effect of reusing the light of the deflection component that was wasted by the laser light emitted from the ceramic laser by providing the laser light phase difference generating means, and the image display device It is useful as a laser light source device used for the light source of

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Green laser light source apparatus 3 Red laser light source apparatus 4 Blue laser light source apparatus 31 Semiconductor laser 34 Solid-state laser element 35 Wavelength conversion element 36 Concave-surface mirror 42 Film | membrane (1st reflection member)
46 Film (second reflecting member)
50 λ / 4 film (laser beam phase difference generating means)
80 Optical phase difference generator (Laser light phase difference generating means)

Claims (6)

A semiconductor laser that outputs excitation laser light;
A solid-state laser element that outputs an infrared laser beam having a fundamental wavelength by an excitation laser beam output from the semiconductor laser;
A wavelength conversion element that converts the wavelength of the laser light output from the solid-state laser element to ½,
In the solid-state laser element, a first reflection is provided on a surface where an excitation laser beam is input from the semiconductor laser and reflects a laser beam having a fundamental wavelength and a laser beam converted and output by the wavelength conversion element. A member and a second reflecting member that transmits the laser beam converted and output by the wavelength conversion element and reflects the infrared laser beam having the fundamental wavelength;
A laser light phase difference generating means between the first reflecting member and the second reflecting member in the laser light path having the fundamental wavelength;
With
The laser beam phase difference generating means provides a phase difference to the infrared laser beam having the fundamental wavelength and rotates the polarization direction thereof. The laser light source device according to claim 1, wherein the laser light phase difference generating means is a birefringent material. 2. The laser light source device according to claim 1, wherein the laser light phase difference generating means is a thin film, and the thickness thereof is a thickness that shifts the phase of the infrared laser light having the fundamental wavelength by [pi] / 2. The laser light source device according to claim 3, wherein the thin film is provided on one end face of the wavelength conversion element or on the solid-state laser side of the second reflecting member. 3. The laser light source device according to claim 2, wherein one surface of the laser light phase difference generating means is spherical. The semiconductor laser, the solid-state laser element, the wavelength conversion element, the first reflecting member, and the second reflecting member are integrally supported on one base. The laser light source device according to any one of claims 1 to 5.

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