JP2001044540A - Laser light generating device and optical signal amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the resistance to optical power of a laser light generating device and an optical signal amplifier, both of which can be manufactured easily. SOLUTION: A fiber housing box 4, housing a laser fiber 2 composed of a non-silica based optical fiber, is filled with matching oil 6 and excitation light is introduced into the box 4, while the oil 6 is made to flow in the box 4. The excitation light excites the doped core 2a of the laser fiber 2 to generate laser light, while the excitation light is reflected repeatedly in the box 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light generator and an optical signal amplifier, and more particularly, to a laser light generator for generating laser light by supplying excitation light to a laser active material of a laser fiber and an optical signal amplifier. To an optical signal amplifier.

[0002]

2. Description of the Related Art In recent years, in the field of optical communication or optical processing technology, practical use of a low-cost, high-output laser light generator has been desired.

Under such circumstances, an optical fiber laser oscillator or an optical waveguide type laser oscillator can easily have a single oscillation mode by designing and manufacturing by adjusting a core diameter and a refractive index difference between a core and a clad. In addition, by confining the light at high density, the interaction between the laser active substance and the light is enhanced, and by increasing the length, the interaction length can be increased, so that high-efficiency spatially high-quality laser light is generated. It is known that it can.

Here, in order to realize high output or high efficiency of a laser beam, it is necessary to efficiently excite a laser active ion or a dye or other light emitting center added region (usually a core portion) of an optical fiber or an optical waveguide. The challenge is to introduce light.

[0005] However, when the core diameter is set to a single-mode waveguide condition, the diameter is usually several tens of μm in the region where the laser active ions or dyes or other luminescent centers are added (usually the core portion).
It is generally limited to the following, and it is generally difficult to efficiently introduce excitation light into this diameter.

Therefore, a second clad portion made of a transparent material having a lower refractive index than the clad portion is provided outside the clad portion, and the end face is formed by total reflection caused by a difference in refractive index between the second clad portion and the clad portion. The pumping light introduced is confined in the first cladding part and the core part, and the laser light is gradually activated as the confined excitation light passes through the region (usually the core part) where laser active ions or dyes or other luminescent centers are added. 2. Description of the Related Art There is known a method in which excitation light is absorbed by ions, dyes, or other luminescent centers to output high-power laser light. This is a double clad fiber laser. (E.Snitzer, H.Po, FHakimi, R. Tumminelli, an
d BCMcCllum, in Optical Fiber Sensors, Vol.2 of
1988 OSA Tecnical Digest Series (Optical Society of
America, Washington, DC, 1988), paper PD5.).

However, in the case of a double-clad fiber laser, if the cross-sectional shape of the inner cladding is circular, it selectively passes through the vicinity of the area (usually the core) where laser active ions or dyes or other luminescent centers are added. Only the excited excitation light is efficiently absorbed by the laser active material, and the absorption efficiency of the other portions is very low. That is, there is a problem that absorption saturation occurs depending on the mode.

[0008] In order to cope with this problem, a contrivance has been made to make the shape of the inner clad portion rectangular, but it is generally difficult to produce a fiber having a cross-sectional shape other than a circular shape, and the mechanical strength is also insufficient. Tends to be.

[0009] To solve these problems, an optical fiber laser device for introducing excitation light from the side into a region (usually a core portion) to which laser active ions or dyes or other luminescent centers are added in a fiber (Japanese Patent Laid-Open No. -13
5548) and a laser device (Japanese Unexamined Patent Application Publication No.
7) has been proposed.

When the excitation light is introduced from the side into the laser active ion or dye or other emission center added region (usually the core portion), the laser active ion or dye or other emission center added region (usually the core) is usually used. The waveguide length (L) is much longer than the diameter (d) of the core portion, and L / d>
Since 106 or more can be obtained, much more excitation energy can be introduced into the fiber or the waveguide than the method of introducing the excitation light from the cross-sectional direction of the waveguide.

Such an optical fiber laser device (Japanese Patent Application Laid-Open No. 10-135548) and a laser device (Japanese Patent Application Laid-Open No.
In 90097), since the excitation light propagates across the fibers, the gap between the fibers needs to be optically high quality and low loss. Therefore, conventionally, such a low-loss configuration has been realized by adopting a configuration in which the fibers are embedded in an optical adhesive or a configuration in which the fibers are thermally fused.

[0012]

However, since an optical adhesive which is an organic substance is used for filling the gap between the fibers with an optical adhesive, the optical adhesive is easily damaged by excitation light, and There is a problem of low power.

On the other hand, the heat fusion method does not have the problem of light power resistance, but generally requires a difficult manufacturing process. Particularly, in the case of a fiber using non-oxide glass, a crystal is used. Due to the low stability to the formation of a crystal, there is a problem that a crystal is deposited on a fusion surface and fusion is impossible, or the crystal becomes a scattering source and absorption efficiency of excitation light is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a laser light generator using a non-quartz fiber which has high light power resistance and is easy to manufacture.

Another object of the present invention is to provide a laser light generator using a silica-based fiber which has high light power resistance and is easy to manufacture. Still another object of the present invention is to provide an optical signal amplifier using a non-quartz fiber, which has high light power resistance and is easy to manufacture.

[0016]

In order to solve the above-mentioned problems, a laser light generating apparatus for generating a laser beam by supplying excitation light to a laser active material includes a laser active material, An optical fiber having an outer peripheral portion made of a non-quartz-based material to cover, a fluid medium having a refractive index at the wavelength of the excitation light substantially equal to the outer peripheral portion, and filling the inside with the fluid medium; At least a part of the pump medium has an excitation light reflector for confining the excitation light therein, and an excitation light introduction unit for introducing the excitation light into the excitation light reflector, wherein the excitation light reflector is a fluid medium. A laser light generating device characterized in that a part of the flow path is formed.

Here, the optical fiber generates a laser beam, the fluid medium flows while filling gaps between the optical fibers, the excitation light reflecting portion fills the inside with the fluid medium, and at least a part of the optical fiber. And the excitation light is confined inside, and the excitation light introduction unit introduces the excitation light into the excitation light reflection unit.

Further, in a laser light generator for generating laser light by supplying excitation light to a laser active substance, at least one selected from Yb ³⁺ , Er ³⁺ , Ce ³⁺ , Tm ³⁺ , and Ho ^3+. An optical fiber having one kind of laser active material and an outer peripheral portion made of a quartz-based material covering the laser active material; a fluid medium having a refractive index at a wavelength of the excitation light substantially equal to the outer peripheral portion; Is filled with the fluid medium, at least a part of the optical fiber is accommodated, and the pumping light reflecting section for confining the pumping light therein, and a pumping light introducing section for introducing the pumping light into the pumping light reflecting section are provided. In addition, there is provided a laser light generating device, wherein the excitation light reflecting portion forms a part of a flow path of the fluid medium.

Here, the optical fiber generates laser light, the fluid medium flows while filling gaps between the optical fibers, the excitation light reflecting portion fills the inside with the fluid medium, and at least a part of the optical fiber. And the excitation light is confined inside, and the excitation light introduction unit introduces the excitation light into the excitation light reflection unit.

Further, in an optical signal amplifier for amplifying signal light by supplying excitation light to a laser active material, the optical signal amplifier has the laser active material and an outer peripheral portion made of a non-quartz material that covers the laser active material. An optical fiber, a fluid medium having a refractive index at the wavelength of the excitation light substantially equal to the outer peripheral portion, and filling the inside with the fluid medium,
An excitation light reflection unit that accommodates at least a part of the optical fiber and confine the excitation light therein, and an excitation light introduction unit that introduces the excitation light into the excitation light reflection unit; Forms a part of the flow path of the fluid medium.

Here, the optical fiber amplifies the signal light,
The fluid medium flows while filling the gaps between the optical fibers, and the pump light reflecting section fills the inside with the fluid medium, accommodates at least a part of the optical fiber, confine the pump light inside, and introduces the pump light introducing section. Introduces the excitation light into the excitation light reflector.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment of the present invention will be described.

FIG. 1 is a configuration diagram of a laser generator 1 according to the first embodiment. The laser generator 1 is attached to one end of the laser fiber 2, which is a non-quartz-based optical fiber that generates laser light, a fiber storage box 4 in which a part of the laser fiber 2 is stored, and one end of the laser fiber 2. It comprises a reflection mirror 5 and an excitation light introducing fiber 3 for introducing excitation light into the fiber storage box 4. The fiber storage box 4 is provided with a matching oil introduction port 4a for introducing the matching oil 6 into the fiber storage box 4 and a matching oil discharge port 4b for discharging the matching oil 6 from inside the fiber storage box 4. The introduction and discharge of the matching oil 6 are performed.

The laser fiber 2 is stored in a fiber storage box 4 and both ends thereof are connected to the fiber storage box 4.
Place outside of. A reflection mirror 5 is attached to one end of the laser fiber 2 disposed outside the fiber storage box 4.

When a non-quartz fiber using fluoride glass, chalcogenide glass, tellurite glass, or the like is used as the laser fiber 2, its low multiphonon absorption makes it difficult to realize a quartz fiber mainly in the mid-infrared region. Laser oscillation including the wavelength becomes possible. For example,
When Ce ³⁺ is used as the material of the doped core 2a, the wavelength of the emitted laser is 5 μm, and when Pr ³⁺ is used, laser beams having wavelengths of 5 μm, 1.3 μm, and 2.3 μm are used. Can send. In addition, when the material of the doped core 2a in the non-quartz fiber and the wavelength of the transmission laser corresponding thereto are listed, Nd ³⁺ : 5 μm,
2.5 μm / Tb ³⁺ : 5 μm / Dy ³⁺ : 3 μm, 1.3
4 μm, 1.7 μm / Ho ³⁺ : 5 μm, 4 μm, 3 μm
m, 2 μm / Er ³⁺ : 3 μm, 3.5 μm, 4 μm / T
m ³⁺ : 5.5 μm, 4 μm, 2 μm, 1.2 μm / Eu
²⁺ : 0.5 to 0.4 μm.

In general, fluoride glass or chalcogena
Eido glass, tellurite glass, etc. have an ESA (excitation level
Multi-photon absorption by silica-based glass
Its intensity is large and the frequency increases from long wavelength to short wavelength.
Exchange is possible. For example, Er ³⁺Green light laser by P
r³⁺Red, green, blue laser, Tm³⁺Blue Ray by
And the like are known.

In an optical amplifier, a fluoride or chalcogenide glass fiber doped with Pr ³⁺ can amplify an optical signal having a wavelength in the 1.3 μm band, which is difficult to amplify with a silica-based fiber. In addition, multi-component aluminosilicate glass or tellurite glass to which Er ³⁺ is added has less wavelength dependence of amplification gain in 1.5 μm band optical signal amplification than silica-based fiber, and is very useful in wavelength multiplexed optical communication. Broadband amplification becomes possible.

The excitation light introducing fiber 3 is attached so that its tip reaches the inside of the fiber housing box 4, and irradiates the fiber housing box 4 with excitation light from its tip. As excitation light sources, generally commercially available wavelengths of 1.5 μm, 0.98 μm, 0.9 μm, 0.8 μm
m, 0.67 μm LD or the like is used. In addition, an LD-pumped solid-state laser can be used as a pump light source. in this case,
Wavelengths such as 1.06 μm, 1.1 μm, and 0.53 μm can be used.

The matching oil 6 is preferably of a low viscosity in order to increase fluidity. Further, since a non-quartz glass clad 2b described later is deteriorated by moisture, the matching oil 6 preferably has a small moisture content.

FIG. 2 is an enlarged sectional view showing the inside of the fiber storage box 4. Fiber storage box 4
First, a gold plating layer 4c is formed by performing gold plating on one surface, and a transparent fluororesin clad layer 4d of a transparent fluororesin is formed on the surface of the gold plating layer 4c.

The laser fiber 2 housed in the fiber housing box 4 is composed of a doped core 2a for generating laser light by excitation light and a non-quartz glass clad 2b surrounding the core. It has a coaxial configuration with the quartz glass clad 2b as the outer periphery. Each laser fiber 2 is filled in its gap with a matching oil 6 having fluidity.

Here, the non-quartz glass cladding 2b and the matching oil 6 have substantially the same refractive index of light, and the transparent fluororesin cladding layer 4d has a higher light refractive index than the non-quartz glass cladding 2b and the matching oil 6. Of which the refractive index is small. Also, the doped core 2a
Is used whose refractive index of light is higher than that of the non-quartz glass clad 2b.

Next, the operation of the laser light generator 1 of this embodiment will be described with reference to FIGS. First, the flow of the matching oil 6 will be described.

The matching oil 6 to which pressure is applied by a pump or the like is injected into the fiber delivery box 4 from the matching oil inlet 4a. The matching oil 6 injected into the fiber income box 4 fills the inside of the fiber storage box 4 without any gap, and is discharged from the matching oil outlet 4b. As a result, the matching oil 6 is placed inside the fiber delivery box 4.
Is constantly flowing. In general, non-quartz fibers have lower heat resistance than quartz fibers. When a non-quartz fiber is used, the flow of the matching oil 6 prevents not only the deterioration of the matching oil 6 but also the deterioration of the non-quartz fiber.

Next, the operation of laser light generation will be described. The excitation light introduced into the fiber storage box 4 by the excitation light introducing fiber 3 travels inside the fiber storage box 4 while traversing the laser fiber 2 and the matching oil 6 in the fiber storage box 4. The excitation light reaching the inner wall is reflected by the gold plating layer 4c or the transparent resin clad layer 4d. The reflected excitation light travels in the fiber storage box 4 in the same manner, and repeats reflection on the gold plating layer 4c or the transparent fluororesin cladding layer 4d.

At this time, a part of the excitation light traversing each laser fiber 2 reaches the doped core 2a, and the doped core 2a irradiated with the excitation light generates laser light. The generated laser light travels inside the doped core 2 a and reaches both ends of the laser fiber 2. The laser light reaching the side where the reflection mirror 5 is installed among the both ends of the laser fiber 2 is reflected there,
It is taken out from the other end of the laser fiber 2.

As described above, in the present embodiment, the laser fiber 2 is housed in the fiber housing box 4, filled with the matching oil 6, and the excitation light is introduced into the fiber housing box 4. While repeating reflection inside the fiber storage box 4, the laser fiber 2
Since the laser light is generated by exciting the doped core 2a, efficient laser light generation can be realized with a simple device configuration, and the production cost of the device can be reduced.

Further, since the excitation light is applied while flowing the matching oil 6, a part of the molecules forming the matching oil is not always irradiated with the strong laser light, and the laser resistance of the matching oil 6 is reduced. It can be significantly improved.

Further, since the excitation light is irradiated while the matching oil 6 is flowing, it is possible to cool the non-quartz glass clad 2b which is weak to heat.
The durability of the laser fiber 2 can be improved.

In this embodiment, a non-quartz fiber is used as the laser fiber 2, but the laser active material is Y.
It is also possible to use b ³⁺ , Er ³⁺ , Ce ³⁺ , Tm ³⁺ , Ho ³⁺ or the like, and use quartz glass for the cladding.

The outer periphery of the non-quartz glass clad 2b may be covered with a resin having substantially the same refractive index as that of the non-quartz glass clad 2b at the wavelength of the excitation light. In this case, it is preferable that the coating is as thin as possible because the cooling efficiency can be increased and the probability of occurrence of laser damage is small.

[0042]

Embodiment 1 In the first embodiment, the core diameter is 50 μm.
m, cladding diameter 125 μm, 1 at% Nd ³⁺ inside a core of a ZrF ₄ -based fluoride glass fiber having a numerical aperture of 0.2
A 50 m long laser fiber doped with ions
Packed in a 50x180x30 rectangular container, refractive index 1.51, viscosity at room temperature 30 poise, wavelength 0.5
A transparent matching oil was allowed to flow through this rectangular parallelepiped container at a flow rate of 1 liter / min over 0.85 μm.
This container is formed of a transparent fluororesin having a thickness of 0.5 mm, and the outside thereof is coated with gold. In this container, the side having a length of 180 mm has two horizontal sides at equal intervals.
Opening windows for exciting light of 0 rows × 2 vertical columns are opened, and the windows are provided with a 1.5 m-long exciting light introducing fiber having a rectangular cross section of 1.0 × 0.3 mm (numerical aperture 0.2). ) Is connected. One end of the pump light introducing fiber not connected to the container has a wavelength of 0.8 μm and an output of 1
It was coupled to a 00 W laser diode via an optical lens. One end face of the laser fiber has a reflectivity of 99.9%
Was pressed vertically, and the other end face was left as a fracture surface (reflectance about 4%). Pump light of a total of 2 kW was introduced, and 0.5 k
Laser oscillation of W wavelength of 1.05 μm was confirmed.

Next, a second embodiment will be described with reference to FIG. FIG. 3 is a configuration diagram of the laser light generator 10 according to the second embodiment. The laser light generator 10 of this embodiment includes a laser fiber 11, which is a continuous non-quartz optical fiber, a separator 12, which smoothes the flow of matching oil, a reflection mirror 13, an excitation light LD 14 for introducing excitation light, Mirror-plated metal base 15, matching oil introduction unit 17 for introducing matching oil into metal base 15, and matching oil discharge unit 1 for discharging matching oil from metal base 15
6.

A cylindrical space is provided inside the metal base 15, and the laser fiber 11 is spirally arranged from the outer periphery to the center in the cylinder. Then, a reflection mirror 13 is attached to the end face of the laser fiber 11 located at the center of the spiral, and the other end of the laser fiber 11 is drawn out of the metal base 15. The configuration of the laser fiber 11 is the same as in the first embodiment, and a description thereof will be omitted.

On the laser fiber 11 disposed inside the metal substrate 15, a separator 12 which is a coreless fiber obtained by removing the doped core from the laser fiber 11 is disposed in a spiral shape having no terminal end at the center point. You. The matching oil introduced from the matching oil introduction part 17 flows inside the metal base 15 along the separator 12 and is discharged from the matching oil discharge part 16. Here, the material of the separator 12 is the same as that of the non-quartz glass clad described in the first embodiment, and the refractive index of the light is almost equal to that of the matching oil. .

A plurality of pumping light LDs 14 are arranged on the side surface of the cylinder inside the metal base 15, and the pumping light is introduced into the cylinder. The introduced excitation light excites the laser fiber 11 while repeatedly reflecting in the metal substrate 15 to generate laser light. The generated laser light travels to both ends of the laser fiber 11, and the laser light reaching the reflection mirror 13 is reflected there and extracted from the other end of the laser fiber 11.

[0047]

Embodiment 2 In the second embodiment, the core diameter 100
μm, cladding diameter 125 μm, numerical aperture 0.2 AlF ₃
-5 at% of E in the core of ZrF ₄ glass fiber
A laser fiber doped with r ³⁺ ions has an outer circumference of 100 m
It was housed in a housing composed of a gold-plated metal plate in a spiral shape (one layer) of mφ. Then, a 100 μm-thick non-core (single-layer) AlF ₃ -ZrF ₄ -based glass fiber having a thickness of 100 μm was disposed as a separator on the laser fiber thus disposed. This fiber serves to smooth the flow of the matching oil. Since this separator is made of the same material as the cladding of the laser fiber, it becomes optically identical when immersed in matching oil and does not hinder the progress of the excitation light at all. A matching oil introduction part and a discharge port for flowing the matching oil were provided near the end face of the separator, and the matching oil having a refractive index of 1.448 was flowed at a rate of 0.1 liter / min. Excitation light is generated by a pulsed laser diode having an oscillation wavelength of 0.98 μm arranged around the disk.
00W was input. One end face of the laser fiber has a reflectivity of 99.
% Of the mirror was pressed and the other end face was left broken. As a result, a wavelength of 50 W on average and 100 Hz repetition
8 μm band pulse laser oscillation was confirmed.

Next, a third embodiment will be described with reference to FIG. FIG. 4 is a configuration diagram of a laser light generator 20 according to the third embodiment. Laser light generator 20
Are a series of non-quartz-based optical fibers, a laser fiber 21, a reflection mirror 22, an inner component 23f, an outer component 23e, a metal housing 23, a matching oil introducing portion 23b, a matching oil discharging portion 23a, and a matching oil. Fiber 23 for smooth flow
c, 23d.

The metal casing 23 has a gold-plated inside, and has a cylindrical outer structure 23e inside. Inside the outer component 23e, a cylindrical inner component 2 having a smaller bottom radius than the outer component 23 is provided.
3f is arranged, and the upper and lower spaces enclosed by the side surfaces of the inner structure 23f and the outer structure 23e are sealed by closing the upper and lower spaces with a plate provided with a transparent fluororesin layer on the surface of a gold plating layer. Inner component 23f and outer component 23e
Are made of a transparent fluororesin, and the inner side structure 23f is subjected to gold plating on its inner side surface.

The laser fiber 21 has an inner structure 23f.
Inner structure 2 by being wound around the side of the
It is arranged in the space surrounded by the side surface of 3f and the side surface of the outer component 23e, and both ends thereof are drawn out of the metal housing 23. The reflection mirror 22 is attached to one end of the laser fiber 21 drawn out of the metal housing 23, and the other end is arranged as a broken surface.

The side surface of the inner structure 23f and the outer structure 23
A matching oil introduction part 23b and a matching oil discharge part 23a are arranged above the space surrounded by the side surface of e, and the matching oil is circulated inside this space.

In this space, a plurality of separate fibers 23c and 23d are arranged. Each of the separate fibers 23c and 23d is disposed outside the laser fiber 21 wound around the side surface of the inner member 23f.
3 are arranged in a direction perpendicular to the bottom surface. Each of the separate fibers 23c and 23d has the same thickness as the gap between the side surface of the inner member 23f and the side surface of the outer member 23e. To form a flow path.

A plurality of separate fibers 23 are arranged.
c and 23d, the separate fiber 23c disposed between the matching oil introduction portion 23b and the matching oil discharge portion 23a has the same length as the height of the inner component 23f and the outer component 23e, and the matching oil is introduced. The region where the portion 23b is connected is divided into the region where the matching oil discharge portion 23a is connected.

The length of the separate fiber 23d is shorter than that of the separate fiber 23c, and the matching oil passes through the gap created thereby. These separate fibers 23d are arranged such that one end thereof is in contact with an upper surface or a lower surface of a space surrounded by the inner structure 23f and the outer structure 23e, and one separate fiber 23d is formed by the inner structure 23f and the outer structure 2d.
3e, when it is arranged in contact with the upper surface of the space surrounded by the separate fiber 23d,
Is a separate fiber disposed in contact with the lower surface of the space surrounded by the inner component 23f and the outer component 23e, and disposed in contact with the lower surface of the space surrounded by the inner component 23f and the outer component 23e. The separate fiber 23d arranged next to 23d is arranged in contact with the upper surface of the space surrounded by the inner structure 23f and the outer structure 23e. By arranging the separate fibers 23d in this manner, the matching oil flows while moving up and down on the side surfaces of the inner component 23f and the outer component 23e.

Here, the separate fibers 23c and 23
d is made of the same material as the non-quartz glass clad described in the first embodiment, and does not hinder the progress of the excitation light because the matching oil and the refractive index of the matching oil are almost equal.

The excitation light is emitted from above the space surrounded by the inner and outer components 23f and 23e, and the emitted excitation light excites the laser fiber 21 while repeating reflection in this space. The resulting laser light is
The laser light is extracted from one end of the laser fiber 21 to which the reflection mirror 22 is not attached.

[0057]

Embodiment 3 In the third embodiment, the core diameter is 50 μm.
m, clad diameter 125 μm, numerical aperture 0.2 Ga-Na
-0.4 at% Dy in the core of S-based glass fiber
³⁺ ion doped laser fiber around 100mm
One layer was wound around the side surface of the φ cylinder. This cylinder is made of a transparent fluorine resin, and the inside thereof is gold-plated. Then, a coreless (single layer) G having a thickness of 100 μm is provided outside the wound laser fiber as shown in FIG.
An a-Na-S-based glass fiber was disposed as a separator. This fiber serves to smooth the flow of the matching oil. This separator is made of the same material as the cladding of the laser fiber, and when immersed in the matching oil, it becomes optically the same as the cladding and the matching oil, and does not hinder the progress of the excitation light at all.
An outer diameter of 100.3
A transparent fluororesin having a thickness of 0 mm and a thickness of 0.5 mm is arranged. The outside was covered with a metal mold having a mirror surface of a split inner metal surface. An inlet and an outlet for flowing the matching oil are provided at the upper part of the cylinder, and the matching oil having a refractive index of 2.14 was flowed at a rate of 0.1 liter / min. Excitation light was emitted by a laser diode having an oscillation wavelength of 0.8 μm arranged around the cylinder, and a total of 2.5 kW was applied. One end face of the laser fiber was pressed against a mirror having a reflectivity of 99% with respect to light having a wavelength of 3.3 μm, and the other end face was kept as a fracture surface. As a result, laser oscillation in the 3.3 μm band at a wavelength of 150 W was confirmed.

Next, a fourth embodiment will be described with reference to FIG. FIG. 5 is a configuration diagram of a laser light generator 30 according to the fourth embodiment. The laser light generator 30 of the present embodiment includes a continuous laser fiber 31, a matching oil introduction unit 32, optical ducts 33a and 33b for introducing excitation light into the laser fiber 31, a matching oil discharge unit 34, a reflection mirror 35, and a surface. It is composed of gold wires 37a and 37b processed with a transparent fluororesin, and a metal substrate 36 whose surface is plated with gold and whose surface is processed with a transparent fluororesin.

The laser fibers 31 are arranged in a plane on the metal substrate 36 while being folded at a plurality of positions. The laser fibers 31 are arranged at both ends of the row of the laser fibers 31 arranged in a plane on the metal substrate 36. Parallel gold wire 37
a and 37b are arranged.

Two optical ducts 33a and 33b are arranged on the laser fiber 31 arranged in the metal base 36, and excitation light is introduced into the laser fiber 31 via these optical ducts 33a and 33b. Then, the laser fiber 31 and the gold wire 3 placed in these metal bases 36 are arranged.
7a, 37b and the light ducts 33a, 33b are covered with a metal substrate 36 by plating a surface of which is plated with gold and further processing the surface with a transparent fluororesin.
6 is stored. At this time, since the gold wires 37a and 37b are arranged, the rows of the laser fibers 31 arranged in the metal substrate 36 are subjected to gold plating on the gold wires 37a and 37b, the metal substrate 36, and the surface thereof. Is surrounded by a transparent fluororesin-processed plate,
Matching oil introduction section 32 and matching discharge section 34
The other parts will be sealed.

The matching oil is introduced from the matching oil introduction part 32, and flows while filling the laser fiber 31 disposed in the metal base 36, and is discharged from the matching oil discharge part 34.

The excitation light is introduced into the light ducts 33a and 33b, and the excitation light introduced into the light ducts 33a and 33b is introduced into the laser fiber 31 in the metal base 36. The laser fiber 31 into which the excitation light is introduced generates laser light, the generated laser light is transmitted to both ends of the laser fiber 31, and the laser light reaching the end face where the reflection mirror 35 is not installed is extracted therefrom. The laser light that has reached the side where the reflection mirror 35 is arranged is reflected there, and is extracted from the end face where the reflection mirror 35 is not installed.

[0063]

Embodiment 4 In the fourth embodiment, the core diameter is 50 μm.
m, cladding diameter 125 μm, numerical aperture 0.2 AlF ₃ -based fluoride glass fiber core, 1.0 at% N
A continuous laser fiber was formed in a shape of a total length of 200 × 25 mm in width, which was co-doped with d ³⁺ ions and 0.01 at% of Ce ³⁺ ions, and was densely arranged in a flat plate shape while being folded. For the base, a flat plate with a mirror-finished gold surface and a transparent fluororesin film with a thickness of 0.01 μm uniformly applied were used, and at both ends of a row of laser fibers arranged in a plane on the base,
A 200 μm pure gold wire thinly coated with a transparent fluororesin was arranged in parallel with the laser fiber.

Then, a metal plate having a mirror-finished gold-plated surface having a window for introducing excitation light into an optical duct coated with 0.01 mm transparent fluororesin was placed on the upper part of the laser fibers arranged on the substrate.

Here, since the confidentiality of both ends is enhanced by the pure gold wires arranged at both ends of the laser fiber, the matching oil can flow at a high pressure. A mask that reflects a laser beam with a wavelength of 1.05 μm is placed so as to traverse the entire fiber alignment section at right angles, and an excimer laser (wavelength: 256 nm) is irradiated on the mask to induce a change in the refractive index, thereby causing a laser beam A chirped grating was formed inside the core of the fiber.
The chirped grating corresponds to multi-mode dispersion, and lowers the transmittance around a wavelength of 1.05 μm in each mode. As a result, amplified spontaneous emission light having a wavelength of around 1.05 μm is suppressed, and a wavelength of 1.33 μm
Laser oscillation becomes possible.

A matching oil having a refractive index of 1.432 was flowed at a rate of 0.1 liter / minute from the matching oil introducing section, and a total of 2 pumping light from a laser diode having an oscillation wavelength of 0.8 μm was passed through an optical duct provided. .8 kW was input. One end face of the laser fiber was pressed against a mirror having a reflectivity of 99%, and the other end face was left as a broken surface. As a result, laser oscillation in the 1.33 μm wavelength band of 0.5 kW was confirmed.

Next, a fifth embodiment will be described with reference to FIG. FIG. 6 is a configuration diagram of an optical signal amplifier 50 according to the fifth embodiment. The optical signal amplifier 50 includes a laser fiber 51, which is one continuous non-quartz optical fiber, a winding drum 52 for winding the laser fiber 51, an excitation light introducing fiber 53, a matching oil introducing section 54,
It comprises a matching oil discharge portion 55, a bundle portion 57, an O-ring 58, a partition wall 59, and a metal jig 60 whose inner surface is gold-plated and whose surface is processed with a transparent fluororesin.

The laser fiber 51 is folded at a plurality of locations and bundled in the bundle 57. Laser fiber 51
Is wound around and fixed to winding drums 52 located at both ends of the bundle portion. Both end faces of the laser fiber 51 are arranged as broken surfaces.

At both ends of the bundle section 57 in the longitudinal direction of the laser fiber 51, tips of a plurality of excitation light introducing fibers 53 are arranged to introduce the excitation light into the bundle section 57.

A partition wall 59 is attached to the central portion in the longitudinal direction of the bundle portion 57 so as to sandwich the bundle portion 57, and an O-ring 58 is mounted outside the partition wall 59.

The laser fiber 51, the winding drum 52, the excitation light introducing fiber 53, the bundle portion 57, the partition wall 59, and the O-ring 58 thus arranged are
It is housed inside a box-shaped metal jig 60, and its upper part is covered with a plate whose inside is gold-plated and whose surface is covered with a transparent fluororesin.

At this time, both end portions of the laser fiber 51 and an end surface portion of the excitation light introducing fiber 53 which is not connected to the bundle portion are arranged outside the metal jig 60. The partition 59 divides the inside of the metal jig 60 into two regions, and the O-ring 58 enhances the security. A matching oil introduction section 54 is connected to one area divided by the partition wall 59, and a matching oil discharge section 55 is attached to the other area.

FIG. 7 shows the A of the bundle unit 57 in FIG.
FIG. In the bundle portion 57, the folded laser fibers 51 are bundled, and the gap between the bundles is filled with the matching oil 61. Laser fiber 5
1 is a doped core 51a and a non-quartz glass clad 51
b, and has a coaxial structure with the doped core 51a as the center and the non-quartz glass clad 51b as the outer periphery.

The outer wall portion of the bundle portion is composed of a mirror-finished gold-plated metal jig 57b whose inside has been mirror-plated and a transparent fluororesin clad 57a that covers the surface of the mirror-finished gold-plated portion of the mirror-plated metal jig 57b. , And has a structure in which the light is reflected inside the excitation light bundle portion taken in.

Here, the non-quartz glass clad 51b and the matching oil 61 have substantially the same refractive index of light, and the light refractive index of the doped core 51a is larger than that of the non-quartz glass clad 51b and the matching oil 61. . The refractive index of light of the transparent fluororesin clad 57a is smaller than that of the non-quartz glass clad 51b, the matching oil 61, and the doped core 51a.

FIG. 8 is a detailed view of the portion B in FIG. The tip of the excitation light introducing fiber 53 is arranged in the portion B, and the excitation light is introduced into the laser fiber 51 by irradiating the excitation light from the end of the excitation light introducing fiber 53. As the pumping light introducing fiber 53, a fiber having a relatively large diameter or a belt-like fiber which is well coupled to a commercially available high-power laser diode is used.

In FIG. 8, θp indicates the critical angle of total reflection of the pumping light introducing fiber 53, and the pumping light emitted from the pumping light introducing fiber 53 is 2 × (90−θp).
Is introduced into the laser fiber 51 as light having a spread at an angle of.

Θb indicates the critical angle of total reflection between the matching oil 61 and the transparent fluororesin clad 57a, and the excitation light that reaches the transparent fluororesin clad 57a at an angle within this critical angle of total reflection θb is The transparent fluororesin clad 57 is totally reflected by the clad 57a.
a.

The laser fiber 51 and the transparent fluororesin clad 57a are widened in the section B, which is the section for introducing the pumping light, in order to increase the efficiency of the pumping light introduction. The 51 and the transparent fluororesin clad 57 a have a spread that has an angle of θt to the outside with respect to the central axis of the bundle portion 57.

Here, it is desirable that all the excitation light introduced from the excitation light introduction fiber 53 into the laser fiber 51 be totally reflected by the transparent fluororesin clad 57a and be introduced into the bundle portion 57. Is the angle between the excitation light irradiated from the excitation light introduction fiber 53 and the surface of the transparent fluororesin clad 57a, and the critical angle of total reflection θb
Must be: This pumping light introducing fiber 53
Light and transparent fluororesin clad 57a irradiated from the
The largest surface angle is caused by the fact that the excitation light emitted from the excitation light introducing fiber 53 is a transparent fluororesin having an angle θt extending outward with respect to the central axis of the bundle portion 57 described above. The time when the light reaches the clad 57a, and the angle between the excitation light irradiated from the excitation light introducing fiber 53 and the surface of the transparent fluororesin clad 57a at that time is represented by (θp + θt). for that reason,
The spread of the laser fiber 51 and the transparent fluororesin clad 57a in the portion B is such that the spread angle θt to the outside of the portion B is (θ
p + θt) <θb.

Next, the operation of the laser generator 50 will be described with reference to FIG. The matching oil introduced from the matching oil introduction part 54 sees one area branched by the partition wall 59, and then flows inside the bundle part 57 to reach the other area branched by the partition wall 59. After that, the matching oil fills the region and is discharged from the matching oil discharge unit 55.

The pumping light introduced from the pumping light introducing fiber 53 reaches the doped core 51 a of the laser fiber 51 while repeating reflection in the bundle portion 57, and the laser fiber 51 irradiated with the pumping light passes from one end of the laser fiber 51. The introduced set signal light is amplified. Then, the amplified signal light is extracted from the other end face.

[0083]

Embodiment 5 In the fifth embodiment, the core diameter is 10 μm.
m, a cladding diameter of 125 μm, and a numerical aperture of 0.11 inside a multi-component aluminosilicate glass fiber core of 5000
A laser fiber doped with a laser fiber co-doped with Er ³⁺ ions of ppmwt and Yb ³⁺ ions of 5 wt% was folded so that the bundle portion length became 250 mm. By using a fiber having a total length of 230 m and making the number of turns of the bundle 452 times, the length per round trip of the fiber was set to 1000 mm. A total of 10 excitation light introducing fibers each having a rectangular cross section of 10.0 × 0.1 mm were inserted into both end surfaces of the bundle portion, each of which was surrounded by a metal jig having a partition wall attached at the center. The metal jig was made of brass, its surface was subjected to a mirror-finished pure gold plating process, and its surface was covered with a transparent fluorine resin having a refractive index of 1.34.

A transparent fluororesin having a refractive index of 1.34 is applied to the portion of the laser fiber protruding from the excitation light introducing portion, and a transparent ultraviolet curing resin having a refractive index of 1.445 is applied to the excitation light introducing fiber. did.

The laser main body thus constituted was housed in a metal housing. At this time, the inside of the metal housing was divided into two regions by the partition wall of the laser main body. A matching oil introduction section is provided in one area, and a matching oil discharge section is provided in the other area. And
The matching oil introduction unit was connected to an oil circulation pump, and a transparent matching oil having a refractive index of 1.523 was poured into the inside of the casing, and pressure was applied to circulate the matching oil so as to pass through the laser bundle portion. The pressure here was 3 kg / cm ² . The fiber take-out part was tightly sealed with resin so that there was no pressure to take out the fiber from the inside. 1.5 wavelength at one end of laser fiber
Signal light of 3 to 1.57 μm was allowed to be simultaneously incident on 40 wavelengths. Then, the other end face was connected to a quartz fiber for extracting signal light by oblique break connection.

The pumping light introducing fiber has an oscillation wavelength of about 0.98 μm and a maximum output of 50 through a cylindrical lens.
The excitation light is coupled to the W semiconductor laser and introduced into the bundle portion. The intensity of the introduced signal light is a total of 6
dBm, and the output of the amplified signal light is 55 dB in total
m. At this time, no laser damage of the matching oil by the excitation light laser was observed. Further, by adjusting the excitation light intensity, the amplification deviation between the wavelengths can be made ± 1d.
B or less.

In the above description, the cross-sectional shape of the laser fiber is described as a circle or a square. However, a laser fiber of another shape may be used, and a rectangular or D-shaped or barrel-shaped laser fiber may be used in terms of efficiency. More preferred.

In each of the first, second, third, fourth, and fifth embodiments, each component has been described as a laser beam generator. It may be used as an amplifier.

Further, in the sixth embodiment, the configuration has been described as an optical signal amplifier. However, in this configuration, a mirror may be attached to one end surface of the laser fiber 51 to be used as a laser light generator. Good.

[0090]

According to the laser beam generating apparatus of the present invention, the pumping light reflecting portion accommodates a fluid medium having a refractive index substantially equal to that of the outer periphery of the non-quartz optical fiber and a sufficiently long optical fiber. An efficient laser light generator that is easy to manufacture can be realized.

Further, since the flowable medium is caused to flow, deterioration of the flowable medium due to heat generation and the like and deterioration of the non-quartz optical fiber can be suppressed, and a laser light generator having high light resistance can be realized. .

The optical signal amplifier of the present invention is easy to manufacture because the pumping light reflecting portion accommodates a fluid medium having substantially the same refractive index as the outer peripheral portion of the optical fiber and a sufficiently long non-quartz optical fiber. Thus, an efficient optical signal amplifier can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a laser generator according to a first embodiment.

FIG. 2 is an enlarged sectional view showing the inside of the fiber storage box 4.

FIG. 3 is a configuration diagram of a laser light generator according to a second embodiment.

FIG. 4 is a configuration diagram of a laser light generator according to a third embodiment.

FIG. 5 is a configuration diagram of a laser light generator according to a fourth embodiment.

FIG. 6 is a configuration diagram of a laser light generator according to a fifth embodiment.

FIG. 7 is a sectional view of the bundle section taken along line AA in FIG. 6;

FIG. 8 is a detailed view of a portion B in FIG. 6;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser light generator 2 laser fiber 3 excitation light introducing fiber 4 fiber storage box 4 a matching oil inlet 4 b matching oil outlet 5 reflecting mirror 6 matching oil

Claims (9)

[Claims] 1. A laser light generator for generating laser light by supplying excitation light to a laser active material, comprising: a laser active material; and an outer peripheral portion made of a non-quartz material that covers the laser active material. Having an optical fiber, a fluid medium having a refractive index at the wavelength of the pump light substantially equal to the outer peripheral portion, filling the inside with the fluid medium, storing at least a part of the optical fiber, and placing the pump light therein. An excitation light reflecting portion for confining the excitation light, and an excitation light introducing portion for introducing the excitation light into the excitation light reflecting portion, wherein the excitation light reflecting portion forms a part of a flow path of the fluid medium. A laser light generator characterized by the above-mentioned. 2. The laser light generator according to claim 1, wherein the fluid medium is a cooling medium that cools the optical fiber and the pumping light introduction unit. 3. The laser active material is Nd ³⁺ , Y
b ³⁺ , Er ³⁺ , Pr ³⁺ , Ce ³⁺ , Tm ³⁺ , Ho ³⁺ , Tb
^2. The material according to claim 1, wherein the material is at least one selected from ³⁺ , Dy3 ⁺ , Eu3 ⁺ , Eu2 ^+, and an organic dye.
The laser light generator according to any one of the preceding claims. 4. The optical fiber is a fluoride glass fiber, a fluorophosphate glass fiber, a chalcogenide glass fiber, an oxychalcogenide glass fiber, a phosphate glass fiber, a tellurite glass fiber, a borate glass fiber, a multi-component aluminosilicate. 2. The laser beam generator according to claim 1, wherein the laser beam generator is at least one of a glass fiber and a plastic fiber. 5. A laser light generator for generating laser light by supplying excitation light to a laser active substance, wherein at least one selected from Yb ³⁺ , Er ³⁺ , Ce ³⁺ , Tm ³⁺ , and Ho ^3+. An optical fiber having one kind of laser active material and an outer peripheral portion made of a quartz-based material covering the laser active material; a fluid medium having a refractive index at a wavelength of the excitation light substantially equal to the outer peripheral portion; Is filled with the fluid medium, at least a part of the optical fiber is contained, an excitation light reflection unit that confine the excitation light inside, and an excitation light introduction unit that introduces the excitation light into the excitation light reflection unit. A laser light generator, wherein the excitation light reflecting portion forms a part of a flow path of the fluid medium. 6. The laser light generator according to claim 5, wherein the fluid medium is a cooling medium that cools the optical fiber and the pumping light introduction unit. 7. An optical signal amplifier for amplifying signal light by supplying excitation light to a laser active substance, comprising: the laser active substance; and an outer peripheral portion made of a non-quartz material and covering the laser active substance. An optical fiber, a fluid medium having a refractive index at the wavelength of the pump light substantially equal to the outer peripheral portion, filling the inside with the fluid medium, storing at least a part of the optical fiber, and confining the pump light inside An excitation light reflecting portion, and an excitation light introducing portion that introduces the excitation light into the excitation light reflecting portion, wherein the excitation light reflecting portion forms a part of a flow path of the fluid medium. An optical signal amplifier characterized in that: 8. The optical signal amplifier according to claim 7, wherein the fluid medium is a cooling medium for cooling the optical fiber and the pumping light introduction unit. 9. The optical fiber may be a fluoride glass fiber, a fluorophosphate glass fiber, a chalcogenide glass fiber, an oxychalcogenide glass fiber, a phosphate glass fiber, a tellurite glass fiber, a borate glass fiber, a multi-component aluminosilicate. 8. The optical signal amplifier according to claim 7, wherein the optical signal amplifier is at least one of a glass fiber and a plastic fiber.