JP2009043367A - Optical head device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a connection loss between a semiconductor laser and a waveguide and to simplify the configuration of a substrate. <P>SOLUTION: The optical head device is provided with: a substrate 2 having a thin-film waveguide 3 formed on one surface side; an organic semiconductor laser 5 formed by stacking a plurality of layers on the surface of one end of the thin-film waveguide 3; a light output diffraction grating 7 formed on the surface of the other end of the thin-film waveguide 3 to emit a laser beam from the semiconductor laser 5 and propagated through the thin-film waveguide 3 to reach the other end to the outside of the thin-film waveguide 3; an objective lens 8 disposed above the light output diffraction grating 7 to be space from the same; and an hologram element 9 disposed in a state to be separated from the light output diffraction grating 7 in a space between the light output diffraction grating 7 and the objective lens 8, and adapted to receive a laser beam emitted from the light output diffraction grating 7 to emit it to an objective lens 8, and to receive a laser beam emitted from the objective lens 8 to emit it to a light receiving part 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical head device using a thin film waveguide.

  As this type of optical head device, a plurality of optical head devices (optical pickups) disclosed in Patent Document 1 below are known. Each of the optical head devices includes a substrate having a thin-film waveguide (thin-film waveguide) formed on the surface, a semiconductor laser as a light source bonded to one end of the waveguide by the end face direct coupling method, and a collimating waveguide. A waveguide lens, a waveguide beam splitter that branches the reflected light from the optical disc, a grating coupler that couples the guided light inside the waveguide to the spatially propagated light, and a waveguide that condenses the branched light branched by the waveguide beam splitter. This is common in that it includes a waveguide lens and a light receiving element that receives the condensed branched light. In this case, the collimating waveguide lens, the waveguide beam splitter, and the grating coupler are formed on the waveguide in this order from the junction side of the semiconductor laser.

In addition, each optical head device disclosed in the above publication is configured to directly irradiate the optical disk with the laser beam output from the grating coupler by providing the grating coupler with a condensing function, or to collect the light on the grating coupler. Although it is different from each other in that the laser beam output from the grating coupler is condensed using a grating lens or a convex lens without having a function, the optical system is a discrete component (reflection mirror, Compared to an optical head device composed of a diffraction grating, a prism, various lenses, and the like), it is common in that it is greatly reduced in thickness, size, and weight.
Japanese Patent Laid-Open No. 2-54435 (page 4-6, FIG. 1-5)

  However, the above-described conventional optical head device has the following problems. That is, in this optical head device, since the semiconductor laser is joined to one end of the waveguide, there is a problem that input / output coupling between the semiconductor laser and the waveguide is difficult and coupling loss increases. In addition, since the waveguide beam splitter is composed of a diffraction grating on the waveguide together with the grating coupler, there is a problem in that the structure becomes complicated and the manufacturing cost increases. In addition, the diffraction grating formed on the waveguide may cause a wavelength shift of the guided light (laser light propagating through the waveguide) due to the influence of heat. This is due to the existence of many diffraction gratings. The complexity of the structure also has a problem that the wavelength shift amount of the guided light due to the influence of heat may increase.

  The present invention has been made to solve such problems, and has as its main object to provide an optical head device that can reduce the coupling loss between a semiconductor laser and a waveguide and simplify the configuration of the substrate. To do.

  In order to achieve the above object, an optical head device according to the present invention includes a substrate having a thin film waveguide formed on one surface side, and light emission containing an organic semiconductor material on the surface of one end of the thin film waveguide. An organic semiconductor laser that is formed by laminating a plurality of layers including at least a layer and emits laser light into the thin film waveguide, and is formed on the surface of the other end of the thin film waveguide and the thin film A light output diffraction grating that emits the laser light propagating through the waveguide and reaching the other end to the outside of the thin film waveguide; and the light output diffraction grating above the light output diffraction grating; The objective lens arranged apart from the optical output diffraction grating and the objective lens are arranged in a state of being separated from the optical output diffraction grating and emitted from the optical output diffraction grating. The laser beam is incident Serial thereby emitted toward the objective lens, and a hologram element for emitting the light receiving unit enters the laser beam emitted from the objective lens.

  An optical head device according to the present invention includes at least a substrate having a thin film waveguide formed on one surface side and a light emitting layer containing an organic semiconductor material on a surface of one end of the thin film waveguide. A first organic semiconductor laser formed by laminating a plurality of layers and emitting a first laser beam into the thin film waveguide, and an organic semiconductor material on the surface of the other end of the thin film waveguide A second organic semiconductor laser that is formed by laminating a plurality of layers including at least a light emitting layer that emits a second laser beam in the thin film waveguide, and the first organic semiconductor laser in the thin film waveguide And the second organic semiconductor laser is formed on the surface of a predetermined portion located between the forming portions of each of the second organic semiconductor lasers, and propagates through the thin film waveguide to transmit the laser light reaching the predetermined portion of the thin film waveguide. Go outside An optical output diffraction grating, an objective lens disposed above the optical output diffraction grating and spaced apart from the optical output diffraction grating, and between the optical output diffraction grating and the objective lens Arranged in a state of being separated from the light output diffraction grating, the laser beams emitted from the light output diffraction grating are incident and emitted toward the objective lens and emitted from the objective lens. A holographic element that enters the first laser beam and emits the first laser beam to the first light receiving unit, and that emits the second laser beam emitted from the objective lens and emits the second laser beam to the second light receiving unit. ing.

  According to the optical head device of the present invention, an organic semiconductor laser is directly formed by laminating a plurality of layers including at least a light emitting layer containing an organic semiconductor material on the surface of one end of a thin film waveguide. Thus, the organic semiconductor laser can be bonded to the thin film waveguide with a very small coupling loss as compared with the configuration in which the organic semiconductor laser is coupled to the thin film waveguide by the conventional end face direct coupling method. Further, since the hologram element functioning as a beam splitter is arranged above the substrate, the formation of the waveguide beam splitter on the surface of the thin film waveguide can be avoided, so that the surface of the substrate (specifically, on the thin film waveguide) ) Can be minimized. For this reason, as a result of being able to simplify the structure of the substrate, the product cost can be greatly reduced. In addition, since the number of diffraction gratings on the surface of the waveguide can be reduced by the amount of the waveguide beam splitter, an increase in the wavelength shift of the guided light (laser light) due to heat can be minimized.

  In addition, according to another optical head device according to the present invention, it is possible to record or reproduce information on two types of optical disks having different wavelengths of laser light to be used while exhibiting the same effects as the above optical head device. be able to.

  Preferred embodiments of an optical head device according to the present invention will be described below with reference to the accompanying drawings.

  First, the configuration of the optical head device 1 will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the optical head device 1 includes a substrate 2, a thin film waveguide 3, a laser diffraction grating 4, an organic semiconductor laser 5, an excitation unit 6, a light output diffraction grating 7, an objective lens 8, and a hologram. An element 9 and a light receiving unit 10 are provided, and information is recorded on or reproduced from the optical disk 11. As shown in the figure as an example, the substrate 2 has an outer shape that is rectangular in plan view. The thin film waveguide 3 is linearly formed along the longitudinal direction of the substrate 2 on one surface side of the substrate 2. In this case, the thin-film waveguide 3 is formed by laminating a substance having a refractive index higher than that of the substrate 2 as a thin film by using a thin-film forming technique, and a light wave (laser light in this example) is transmitted in a certain region. It functions as a waveguide confined in and transmitted. As shown in FIGS. 1 and 2, the laser diffraction grating 4 is formed on the surface of one end portion (left end portion in FIGS. 1 and 2) of the thin film waveguide 3 by a thin film formation technique similar to that of the thin film waveguide 3. Is formed directly using. The laser diffraction grating 4 functions as a resonator for the organic semiconductor laser 5.

  The organic semiconductor laser 5 is a known organic semiconductor laser (for example, Japanese Patent Application Laid-Open No. 2004-214276, Japanese Patent Application Laid-Open No. 2006-2006) configured by laminating a plurality of layers (thin films) including a light emitting layer containing an organic semiconductor material. Organic semiconductor lasers disclosed in Japanese Patent No. 93628 and Japanese Patent Application Laid-Open No. 2006-253221 can be employed. The organic semiconductor laser 5 has the above-described plurality of layers formed on the surface of the laser diffraction grating 4 formed at one end of the thin film waveguide 3 by using the same thin film forming technique as that of the thin film waveguide 3. It is directly formed by laminating. As a result, the organic semiconductor laser 5 is bonded to the surface of one end portion of the thin film waveguide 3 through the laser diffraction grating 4 in a state where the coupling loss is extremely small as compared with the conventional end face direct coupling method. ing. In addition, the organic semiconductor laser emits laser light by either of the electric excitation method and the optical excitation method, but the optical excitation method causes less deterioration of the material constituting the organic semiconductor laser than the electric excitation method. For this reason, the organic semiconductor laser 5 employs an optical excitation method. The excitation unit 6 includes an LED (light emitting diode), and outputs light for exciting the organic semiconductor laser 5 when energized. The excitation unit 6 is disposed above the organic semiconductor laser 5.

  As shown in FIGS. 1 and 2, the light output diffraction grating 7 is formed on the surface of the other end portion (the right end portion in FIGS. 1 and 2) of the thin film waveguide 3 by the same thin film formation technique as that of the thin film waveguide 3. Is formed directly using. Further, the light output diffraction grating 7 allows the laser light that has reached (propagated) from the organic semiconductor laser 5 to the other end of the thin film waveguide 3 via the thin film waveguide 3, and the thin film waveguide at the other end. 3 has a function of emitting light to the outside. The objective lens 8 is disposed above the light output diffraction grating 7 and separated from the light output diffraction grating 7. The hologram element 9 is disposed between the light output diffraction grating 7 and the objective lens 8 in a state of being separated from the light output diffraction grating 7. Further, the hologram element 9 functions as a beam splitter, and enters the laser beam emitted from the light output diffraction grating 7 and emits it toward the objective lens 8, and also emits the laser beam (from the objective lens 8 ( The reflected light from the optical disk 11 is incident and emitted to the light receiving unit 10. The light receiving unit 10 includes a plurality of light receiving elements (not shown) and is mounted on the substrate 2. In addition, the light receiving unit 10 outputs information recorded on the optical disk 11, a tracking servo signal, and an electric signal for generating a focus servo signal based on the received laser beam.

  Next, the operation of the optical head device 1 will be described.

  In the optical head device 1, when the excitation unit 6 is energized, the excitation unit 6 irradiates the organic semiconductor laser 5 with light. As a result, the organic semiconductor laser 5 is excited and emits laser light into the thin film waveguide 3 via the laser diffraction grating 4. The light output diffraction grating 7 emits laser light propagating through the thin film waveguide 3 to the outside of the thin film waveguide 3, specifically toward the hologram element 9. The hologram element 9 emits this laser light to the objective lens 8. The objective lens 8 condenses and irradiates the laser beam from the hologram element 9 onto the optical disk 11 and emits the reflected light from the optical disk 11 to the hologram element 9. The hologram element 9 emits the incident laser light to the light receiving unit 10, and the light receiving unit 10 converts the laser light into various electric signals and outputs them.

  As described above, in the optical head device 1, the organic semiconductor laser 5 is directly formed by laminating a plurality of layers including at least the light emitting layer containing the organic semiconductor material on the surface of one end portion of the thin film waveguide 3. is doing. Therefore, according to the optical head device 1, an organic material is formed on the surface of the thin film waveguide 3 using the thin film formation technique (specifically, on the surface of the thin film waveguide 3 via the laser diffraction grating 4). By directly forming the semiconductor laser 5, the organic semiconductor laser 5 can be formed into the thin film waveguide 3 with extremely little coupling loss as compared with the configuration in which the organic semiconductor laser is coupled to the thin film waveguide by the conventional end face direct coupling method. Can be joined.

  Further, according to this optical head device 1, since the hologram element 9 functioning as a beam splitter is disposed above the substrate 2, the formation of the waveguide beam splitter on the surface of the thin film waveguide 3 can be avoided. Formation of the diffraction grating on the surface of the substrate 2 (specifically, on the thin film waveguide 3) can be minimized (two of the diffraction grating for laser 4 and the diffraction grating for light output 7). For this reason, as a result of being able to manufacture the substrate 2 easily, the product cost can be greatly reduced. In addition, since the number of diffraction gratings that are easily affected by heat can be reduced by the amount of the waveguide beam splitter, an increase in the wavelength shift of guided light (laser light) due to heat can be suppressed to a minimum.

  In addition, this invention is not limited to said structure. For example, the optical head device 1 in which one organic semiconductor laser 5 is mounted on the substrate 2 has been described above. However, as in the optical head device 21 shown in FIGS. A configuration in which the lasers 5a and 5b are mounted on the substrate 2 can also be adopted. Hereinafter, the optical head device 21 will be described. In addition, about the structure same as the optical head apparatus 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  3 and 4, the optical head device 21 includes a substrate 2, a thin film waveguide 3, laser diffraction gratings 4 a and 4 b, organic semiconductor lasers 5 a and 5 b, excitation units 6 a and 6 b, and a light output diffraction grating 22. The objective lens 8, the hologram element 23, and the light receiving portions 10a and 10b are provided, and information is recorded on or reproduced from the optical disc 11. In the optical head device 21, as described later, the organic semiconductor laser 5a emits laser light having a wavelength of 780 nm (for CD), and the organic semiconductor laser 5b emits laser light having a wavelength of 650 nm (for DVD). Information can be recorded on or reproduced from two types of optical disks 11, CD and DVD.

  As shown in FIGS. 3 and 4, the laser diffraction grating 4 a uses the same thin film formation technique as that of the thin film waveguide 3 on the surface of one end portion (left end portion in each figure) of the thin film waveguide 3. Directly formed. On the other hand, the laser diffraction grating 4b is formed as a thin film on the surface of the other end (the right end in each figure) of the thin film waveguide 3 in the same manner as the laser diffraction grating 4a, as shown in each figure. Formed directly using technology. Each of the laser diffraction gratings 4 a and 4 b functions as a resonator for the organic semiconductor laser 5.

  Each of the organic semiconductor lasers 5a and 5b is a known organic semiconductor configured by laminating a plurality of layers (thin films) including a light emitting layer containing an organic semiconductor material in the same manner as the organic semiconductor laser 5 of the optical head device 1. A laser is used, and is formed on the surface of the thin film waveguide 3 via the corresponding laser diffraction gratings 4a and 4b by the same thin film formation technique as that of the organic semiconductor laser 5. In this case, the organic semiconductor laser 5a is a first organic semiconductor laser according to the present invention that emits the first laser light according to the present invention (laser light with a wavelength of 780 nm as an example). It is formed on the surface of the left end in FIGS. 3 and 4 via a laser diffraction grating 4a. On the other hand, the organic semiconductor laser 5b is the second organic semiconductor laser in the present invention that emits the second laser light in the present invention (for example, laser light having a wavelength of 650 nm). 3, 4) on the surface of the laser diffraction grating 4 b.

  Each excitation part 6a, 6b is comprised including LED (light emitting diode) similarly to the excitation part 6 of the optical head apparatus 1. FIG. The excitation unit 6a is disposed above the organic semiconductor laser 5a to excite the organic semiconductor laser 5a, and the excitation unit 6b is disposed above the organic semiconductor laser 5b to excite the organic semiconductor laser 5b. Let

  As shown in FIGS. 3 and 4, the light output diffraction grating 22 is a predetermined portion (between the center of the thin film waveguide 3 or its vicinity as an example) located between the formation portions of the organic semiconductor lasers 5 a and 5 b in the thin film waveguide 3. ) Directly on the surface. The light output diffraction grating 22 emits two types of laser light reaching (propagating) from the organic semiconductor lasers 5 a and 5 b via the thin film waveguide 3 to the outside of the thin film waveguide 3. It has a function. The hologram element 23 is disposed between the light output diffraction grating 22 and the objective lens 8 in a state of being separated from the light output diffraction grating 22. Further, the hologram element 23 enters the laser beam emitted from the light output diffraction grating 22 and emits it toward the objective lens 8. The hologram element 23 functions as a beam splitter, and the laser beam having a wavelength of 780 nm of the laser beam emitted from the objective lens 8 (the reflected beam from the optical disk 11) is used as the first light receiving unit in the present invention. The laser beam having a wavelength of 650 nm is emitted to the light receiving unit 10b. Each of the light receiving portions 10 a and 10 b is configured by a plurality of light receiving elements (not shown) and mounted at different positions on the substrate 2 in the same manner as the light receiving portion 10. The light receiving unit 10a outputs information recorded on the optical disc 11 (CD), a tracking servo signal, and an electrical signal for generating a focus servo signal based on the received laser beam. On the other hand, the light receiving unit 10b outputs information recorded on the optical disc 11 (DVD), a tracking servo signal, and an electric signal for generating a focus servo signal based on the received laser beam.

  Next, the operation of the optical head device 21 will be described.

  In the optical head device 21, when the excitation unit 6a is energized, the excitation unit 6a irradiates the organic semiconductor laser 5a with light. As a result, the organic semiconductor laser 5a is excited to emit laser light (wavelength 780 nm) into the thin film waveguide 3 through the laser diffraction grating 4a. The light output diffraction grating 22 emits laser light propagating through the thin film waveguide 3 to the outside of the thin film waveguide 3, specifically toward the hologram element 23. The hologram element 23 emits this laser light to the objective lens 8. The objective lens 8 condenses and irradiates the laser light from the hologram element 23 onto the optical disk 11 and emits the reflected light from the optical disk 11 to the hologram element 23. The hologram element 23 emits the incident laser light to the light receiving unit 10a, and the light receiving unit 10a converts the laser light into various electric signals and outputs them. On the other hand, when the excitation unit 6b is energized, the excitation unit 6b irradiates the organic semiconductor laser 5b with light. As a result, the organic semiconductor laser 5 b is excited and emits laser light (wavelength 650 nm) into the thin film waveguide 3. The light output diffraction grating 22 emits laser light propagating through the thin film waveguide 3 toward the outside of the thin film waveguide 3 (hologram element 23). The hologram element 23 emits this laser light to the objective lens 8. The objective lens 8 condenses and irradiates the laser light from the hologram element 23 onto the optical disk 11 and emits the reflected light from the optical disk 11 to the hologram element 23. The hologram element 23 emits the incident laser light to the light receiving unit 10b, and the light receiving unit 10b converts the laser light into various electric signals and outputs them. In this manner, by using the optical head device 21, information can be recorded or reproduced on two types of optical discs 11 having different laser light wavelengths.

  As described above, also in the optical head device 21, the organic semiconductor lasers 5 a and 5 b are directly formed on the surface of the thin film waveguide 3. Therefore, according to this optical head device 21, information can be recorded on or reproduced from two types of optical disks 11 having different wavelengths of laser light, and on the surface of the thin film waveguide 3 using a thin film formation technique ( Specifically, the organic semiconductor lasers 5a and 5b are directly formed on the surface of the thin film waveguide 3 through the corresponding laser diffraction gratings 4a and 4b, respectively, so that an organic semiconductor can be formed by a conventional end face direct coupling method. The organic semiconductor lasers 5a and 5b can be bonded to the thin film waveguide 3 with extremely little coupling loss as compared with the configuration in which the laser is coupled to the thin film waveguide.

  Further, according to this optical head device 21, the hologram element 23 functioning as a beam splitter is disposed above the substrate 2, so that the optical head device 21 is guided onto the surface of the thin film waveguide 3 in the same manner as the optical head device 1. Since the formation of the waveguide beam splitter can be avoided, the number of diffraction gratings formed on the surface of the substrate 2 (specifically, on the thin film waveguide 3) is minimized while reducing the size of the apparatus (laser diffraction grating 4a, 4b and the light output diffraction grating 22). For this reason, as a result of being able to manufacture the substrate 2 easily, the product cost can be greatly reduced. In addition, since the number of diffraction gratings that are easily affected by heat can be reduced by the amount of the waveguide beam splitter, an increase in the wavelength shift of guided light (laser light) due to heat can be suppressed to a minimum.

1 is a perspective view showing a configuration of an optical head device 1. FIG. FIG. 2 is a cross-sectional view of the optical head device 1 shown in FIG. 3 is a perspective view showing a configuration of an optical head device 21. FIG. FIG. 4 is a cross-sectional view of the optical head device 21 shown in FIG. 3 taken along line XX.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,21 Optical head apparatus 2 Substrate 3 Thin film waveguide 4,4a, 4b Diffraction grating for laser 5,5a, 5b Organic semiconductor laser 7,22 Diffraction grating for light output 8 Objective lens 9,23 Hologram element

Claims (2)

A substrate with a thin film waveguide formed on one side;
An organic semiconductor laser that is formed by laminating a plurality of layers including at least a light emitting layer containing an organic semiconductor material on the surface of one end of the thin film waveguide, and emits laser light into the thin film waveguide;
For light output that is formed on the surface of the other end of the thin film waveguide and that emits the laser light that has propagated through the thin film waveguide and reached the other end to the outside of the thin film waveguide A diffraction grating,
An objective lens disposed above the light output diffraction grating and spaced apart from the light output diffraction grating;
The objective lens is disposed between the light output diffraction grating and the objective lens in a state of being separated from the light output diffraction grating, and the laser light emitted from the light output diffraction grating is incident thereon. And a hologram element that emits the laser beam emitted from the objective lens and emits the laser beam to the light receiving unit. A substrate with a thin film waveguide formed on one side;
A first laser beam is formed by laminating a plurality of layers including at least a light emitting layer containing an organic semiconductor material on the surface of one end of the thin film waveguide, and emits a first laser beam into the thin film waveguide. An organic semiconductor laser,
A second layer is formed by laminating a plurality of layers including at least a light emitting layer containing an organic semiconductor material on the surface of the other end of the thin film waveguide, and emits a second laser beam into the thin film waveguide. An organic semiconductor laser,
The thin film waveguide is formed on the surface of a predetermined portion located between the formation portions of the first organic semiconductor laser and the second organic semiconductor laser, and propagates through the thin film waveguide to the predetermined portion. A light output diffraction grating for emitting each of the reached laser beams to the outside of the thin film waveguide;
An objective lens disposed above the light output diffraction grating and spaced apart from the light output diffraction grating;
The optical output diffraction grating and the objective lens are disposed in a state of being separated from the optical output diffraction grating, and the respective laser beams emitted from the optical output diffraction grating are incident to the objective lens. The first laser beam emitted from the objective lens is incident on the first light-receiving unit, and the second laser beam emitted from the objective lens is incident. And a hologram element that emits light to the second light receiving unit.

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