JP4344066B2 - Laser light generator and optical signal amplifier - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser light generation device and an optical signal amplifier, and more particularly to a laser light generation device that generates laser light by supplying excitation light to a laser active material of a laser fiber and an optical signal amplifier that amplifies the optical signal.
[0002]
[Prior art]
In recent years, in the field of optical communication or optical processing technology, it is desired to put into practical use an inexpensive and high-power laser light generator.
[0003]
Under such circumstances, an optical fiber laser oscillator or an optical waveguide type laser oscillator can be easily made into a single oscillation mode by adjusting and adjusting the core diameter and the refractive index difference between the core and the clad, and can emit light. Enhancing the interaction between the laser active substance and light by confining at a high density, and increasing the interaction length by increasing the length, it is possible to generate spatially high-quality laser light with high efficiency. It has been known.
[0004]
Here, in order to achieve high output or high efficiency of the laser beam, how to efficiently introduce the excitation light into the laser active ion or dye or other emission center addition region (usually the core) of the optical fiber or optical waveguide It will be a challenge.
[0005]
However, when the core diameter is usually set in the waveguide mode of single mode, the diameter is limited to less than a dozen μm or less of the addition region (usually the core portion) of the laser active ion or dye or other light emission center. It is generally difficult to introduce excitation light well.
[0006]
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 is introduced from the end face by total reflection due to the refractive index difference between the second clad portion and the clad portion. The pumped light is confined in the first cladding part and the core part, and gradually the laser active ions or dyes pass as the confined pumping light passes through the added region (usually the core part) of the laser active ions or dyes or other emission centers. There is known a method in which excitation light is absorbed by other emission centers and high-power laser light is output. This is a double clad fiber laser. (E. Snitzer, H. Po, FHakimi, R. Tumminelli, and BCMcCllum, in Optical Fiber Sensors, Vol. 2 of 1988 OSA Tecnical Digest Series (Optical Society of America, Washington, DC, 1988), paper PD5.).
[0007]
However, in the case of a double-clad fiber laser, if the cross-sectional shape of the inner cladding part is circular, excitation light that selectively transmits near the active region of the laser-active ion or dye or other emission center (usually the core part) Only the laser active material is efficiently absorbed, and the absorption efficiency of the other part is very low. That is, there is a problem that absorption saturation occurs due to the mode.
[0008]
Therefore, a device has been devised to make the shape of the inner cladding part rectangular, but it is generally difficult to produce a fiber having a cross-sectional shape other than circular, and the mechanical strength tends to be insufficient. is there.
[0009]
In order to solve these problems, an optical fiber laser device that introduces pumping light from the side surface into a doped region (usually a core portion) of a laser active ion or dye or other emission center in a fiber (Japanese Patent Laid-Open No. 10-135548) And a laser device (Japanese Patent Laid-Open No. 10-190097) have been proposed.
[0010]
When excitation light is introduced from the side into the laser active ion or dye or other emission center addition region (usually the core), the laser active ion or dye or other emission center addition region (usually the core portion) ) Has a very long waveguide length (L) compared to the diameter (d) of L), and L / d> 106 or more, so that much more excitation energy than the method of introducing excitation light from the cross-sectional direction of the waveguide can be obtained. It can be introduced into a fiber or waveguide.
[0011]
In such an optical fiber laser device (Japanese Patent Laid-Open No. 10-135548) and a laser device (Japanese Patent Laid-Open No. 10-190097), the excitation light propagates across the fiber, so that the gap between the fibers is optically quality-enhanced. However, it is necessary to have a high and low loss configuration. Therefore, conventionally, such a low-loss configuration has been realized by adopting a configuration in which a fiber is embedded in an optical adhesive or a configuration in which fibers are heat-sealed.
[0012]
[Problems to be solved by the invention]
However, since the optical adhesive which is an organic substance is used for filling the gap between the fibers with the optical adhesive, there is a problem that the optical adhesive is easily damaged by the excitation light and the light resistance is low.
[0013]
On the other hand, there is no problem of light resistance in the heat fusion method, but generally a difficult manufacturing process has to be taken, especially in the case of a fiber using non-oxide glass, stability against crystallization. Since the degree is low, there is a problem that crystals are deposited on the fused surface, making fusion impossible, or the crystals become a scattering source and the absorption efficiency of excitation light is lowered.
[0014]
The present invention has been made in view of these points, and an object of the present invention is to provide a laser beam generator using a non-quartz fiber that has high light resistance and is easy to manufacture.
[0015]
Another object of the present invention is to provide a laser beam generator using a silica-based fiber that has high light resistance and is easy to manufacture.
Furthermore, another object of the present invention is to provide an optical signal amplifier using a non-quartz fiber that has high optical power resistance and is easy to manufacture.
[0016]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in a laser light generator for generating laser light by supplying excitation light to a laser active material, an outer periphery made of the laser active material and a non-quartz material covering the laser active material possess a part, substantially equal to fluid medium and the optical fiber 1 connection juxtaposed longitudinally, the refractive index at the wavelength of the excitation light and the outer peripheral portion at a plurality of positions arranged a predetermined gap, A pumping light reflecting part for containing at least a part of the optical fiber and filling the gap with the fluid medium to confine the pumping light, and a pumping light introducing part for introducing the pumping light into the pumping light reflecting part When have, the optical fiber is arranged in spiral, wherein the gap is composed of the same material as the cladding of the optical fiber, to form a flow path of the fluid medium separator Laser beam generating apparatus characterized by data are provided are provided.
[0017]
Here, the optical fiber generates laser light, the fluid medium flows while filling the gaps between the optical fibers, and the excitation light reflector fills the interior with the fluid medium and houses at least a part of the optical fiber. The excitation light is confined inside, and the excitation light introducing unit introduces the excitation light into the excitation light reflecting unit.
[0018]
Further, in the laser beam generator for generating laser beam by supplying excitation light to the laser active substance, at least one kind selected from Yb ³⁺ , Er ³⁺ , Ce ³⁺ , Tm ³⁺ and Ho ³⁺ is used. a laser active material, possess an outer peripheral portion made of a material of silica-based covering the laser active material, the optical fiber 1 connection juxtaposed longitudinally at a plurality of positions by disposing a predetermined gap, the excitation A flowable medium having a refractive index at the wavelength of light substantially equal to that of the outer peripheral portion, and an excitation light reflecting portion that contains at least a part of the optical fiber and fills the gap with the flowable medium to confine the excitation light inside. And an excitation light introducing portion that introduces the excitation light into the excitation light reflecting portion, and the optical fiber is arranged in a spiral shape, and the gap is made of the same material as the cladding of the optical fiber. In There is provided a laser beam generator characterized in that a separator for forming a flow path of the fluid medium is provided.
[0019]
Here, the optical fiber generates laser light, the fluid medium flows while filling the gaps between the optical fibers, and the excitation light reflector fills the interior with the fluid medium and houses at least a part of the optical fiber. The excitation light is confined inside, and the excitation light introducing unit introduces the excitation light into the excitation light reflecting unit.
[0020]
Further, in the optical signal amplifier for amplifying the signal light by supplying excitation light to the laser active material, possess said laser active material, and an outer peripheral portion made of a material of non-silica-based covering the laser active material, a predetermined A series of optical fibers arranged in parallel in the longitudinal direction at a plurality of locations, a fluid medium having a refractive index at the wavelength of the excitation light substantially equal to that of the outer peripheral portion, and at least a part of the optical fiber the pay has a pumping light reflecting portion confining said gap the excitation light to the interior by filling in the fluid medium, and a pumping light introducing part for introducing the excitation light to the excitation light reflecting portion, wherein optical fibers are arranged spirally, wherein the gap, that is composed of the same material as the cladding of the optical fiber, a separator for forming a flow path of the fluid medium is provided Optical signal amplifier of symptoms is provided.
[0021]
Here, the optical fiber amplifies the signal light, the flowable medium flows while filling the gaps between the optical fibers, and the excitation light reflecting portion fills the inside with the flowable medium and accommodates at least a part of the optical fiber. The excitation light is confined inside, and the excitation light introducing unit introduces the excitation light into the excitation light reflecting unit.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a first embodiment of the present invention will be described.
[0023]
FIG. 1 is a configuration diagram of a laser beam generator 1 according to the first embodiment.
A laser beam generator 1 is attached to one end of a laser fiber 2, a laser fiber 2 that is a non-quartz optical fiber connected to one that generates laser light, a fiber storage box 4 that stores a part of the laser fiber 2, and a laser fiber 2. The reflection mirror 5 and the fiber storage box 4 are configured by the excitation light introducing fiber 3 for introducing the excitation light. The fiber storage box 4 is provided with a matching oil inlet 4a for introducing the matching oil 6 into the fiber storage box 4 and a matching oil outlet 4b for discharging the matching oil 6 from the fiber storage box 4. The matching oil 6 is introduced and discharged.
[0024]
The laser fiber 2 is stored in the fiber storage box 4, and both ends thereof are arranged outside the fiber storage box 4. A reflection mirror 5 is attached to one end of the laser fiber 2 arranged outside the fiber storage box 4.
[0025]
When a non-quartz fiber using fluoride glass, chalcogenide glass, tellurite glass, or the like is used as the laser fiber 2, the low multiphonon absorption mainly includes wavelengths in the mid-infrared region that cannot be realized with a silica fiber. Laser oscillation is 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, lasers with wavelengths of 5 μm, 1.3 μm, and 2.3 μm are used. Can transmit light. In addition, when the material of the doped core 2a in the non-quartz fiber and the wavelength of the transmission laser corresponding to them are listed, Nd ³⁺ : 5 μm, 2.5 μm / Tb ³⁺ : 5 μm / Dy ³⁺ : 3 μm, 1.34 μm 1.7 μm / Ho ³⁺ : 5 μm, 4 μm, 3 μm, 2 μm / Er ³⁺ : 3 μm, 3.5 μm, 4 μm / Tm ³⁺ : 5.5 μm, 4 μm, 2 μm, 1.2 μm / Eu ²⁺ : 0 .5 to 0.4 μm.
[0026]
In general, fluoride glass, chalcogenide glass, tellurite glass, etc. have higher multiphoton absorption due to ESA (absorption from the excitation level) than quartz glass, and the frequency from long to short wavelength is high. Up conversion is possible. For example, a green light laser using Er ³⁺ , a red, green and blue laser using Pr ³⁺ , a blue laser using Tm ³⁺ , and the like are known.
[0027]
In an optical amplifier, a fluoride or chalcogenide glass fiber doped with Pr ³⁺ can amplify an optical signal having a wavelength of 1.3 μm, which is difficult to amplify with a silica-based fiber. In addition, in multi-component aluminosilicate glass or tellurite glass with Er ³⁺ added, the wavelength dependence of amplification gain in optical signal amplification in the 1.5 μm band is less than that of silica-based fibers, which is very high in wavelength multiplexing optical communication. Broadband amplification is possible.
[0028]
The pumping light introduction fiber 3 is attached so that the tip thereof reaches the inside of the fiber storage box 4, and the pumping light is irradiated into the fiber storage box 4 from the tip. As the excitation light source, commercially available LDs with wavelengths of 1.5 μm, 0.98 μm, 0.9 μm, 0.8 μm, and 0.67 μm are used. In addition, an LD-excited solid-state laser can be used as an excitation light source. In this case, wavelengths such as 1.06 μm, 1.1 μm, and 0.53 μm can be used.
[0029]
The matching oil 6 is preferably as low as possible in order to increase fluidity. Further, since the non-quartz glass clad 2b described later deteriorates due to moisture, the matching oil 6 preferably has a low moisture content.
[0030]
FIG. 2 is an enlarged cross-sectional view showing the inside of the fiber storage box 4.
The inside of the fiber storage box 4 is formed with a gold plating layer 4c by first being gold plated, and a transparent fluororesin clad layer 4d of transparent fluororesin is formed on the surface of the gold plating layer 4c. Has been.
[0031]
The laser fiber 2 housed in the fiber housing box 4 is composed of a doped core 2a that generates laser light by excitation light and a non-quartz glass cladding 2b that surrounds the doped core 2a. It has a coaxial configuration with 2b as the outer periphery. Each laser fiber 2 is filled with a matching oil 6 having fluidity.
[0032]
Here, the non-quartz glass clad 2b and the matching oil 6 have the same refractive index of light, and the transparent fluororesin clad layer 4d has a light refractive index higher than that of the non-quartz glass clad 2b and the matching oil 6. Use a small one. The doped core 2a has a higher light refractive index than the non-quartz glass cladding 2b.
[0033]
Next, the operation of the laser beam generator 1 according to this embodiment will be described with reference to FIGS. 1 and 2.
First, the flow of the matching oil 6 will be described.
[0034]
The matching oil 6 to which pressure is applied by a pump or the like is injected into the fiber storage box 4 from the matching oil introduction port 4a. Matching oil 6 which is injected into the fiber storage box 4 is filled without gaps inside the fiber storage box 4, and is discharged from the matching oil discharge port 4b. As a result, a state in which the matching oil 6 always flows inside the fiber storage box 4 is created. 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 not only prevents the matching oil 6 from deteriorating but also prevents the non-quartz fiber from deteriorating.
[0035]
Next, the operation of generating laser light will be described.
The pumping light introduced into the fiber storage box 4 by the pumping light introducing fiber 3 proceeds 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 fluororesin cladding layer 4d. The reflected excitation light similarly travels through the fiber storage box 4 and repeats reflection at the gold plating layer 4c or the transparent fluororesin cladding layer 4d.
[0036]
At this time, a part of the excitation light crossing 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 through the doped core 2 a and reaches both ends of the laser fiber 2. The laser beam that has reached the side where the reflecting mirror 5 is installed on both ends of the laser fiber 2 is reflected there and taken out from the other end of the laser fiber 2.
[0037]
As described above, in this embodiment, the laser fiber 2 is stored in the fiber storage box 4, filled with the matching oil 6, and pumping light is introduced into the fiber storage box 4. The pumping light thus introduced is the fiber storage box. Since the laser beam is generated by exciting the doped core 2a of the laser fiber 2 while repeating reflection inside the apparatus 4, efficient laser light generation can be realized with a simple apparatus configuration, and the production of the apparatus Cost reduction is possible.
[0038]
Further, since the excitation light is irradiated while flowing the matching oil 6, a part of the molecules forming the matching oil is not always irradiated with strong laser light, and the laser resistance of the matching oil 6 is remarkably improved. be able to.
[0039]
Furthermore, due to the irradiation with excitation light in flowing matching oil 6, it is possible to cool the heat sensitive non-quartz glass Rasukuraddo 2b, it is possible to improve the durability of the laser fiber 2 .
[0040]
In this embodiment, a non-quartz fiber is used as the laser fiber 2, but Yb ³⁺ , Er ³⁺ , Ce ³⁺ , Tm ³⁺ , Ho ^3+, etc. are used as the laser active material, and quartz glass is used as the cladding. It may be used.
[0041]
Alternatively, a resin that is substantially the same refractive index as that of the non-quartz glass clad 2b and is transparent at the excitation light wavelength may be used to cover the outer periphery of the non-quartz glass clad 2b. In this case, it is possible to better this coating is as thin as possible to increase the cooling efficiency, since the probability of rate Zada images also preferably small.
[0042]
[Example 1]
In the first embodiment, a laser fiber having a length of 50 m in which a core of a ZrF ₄ fluoride glass fiber having a core diameter of 50 μm, a cladding diameter of 125 μm, and a numerical aperture of 0.2 is doped with 1 at% Nd ³⁺ ions. Was packed in a rectangular parallelepiped container of 250 × 180 × 30, and a transparent matching oil was flowed into the rectangular parallelepiped container at a flow rate of 1 liter / min over a wavelength of 0.5 to 0.85 μm with a refractive index of 1.51 and a viscosity of 30 poise at room temperature. . This container is formed of a transparent fluororesin having a thickness of 0.5 mm, and its outer side is coated with gold. In this container, excitation light introduction windows of 20 horizontal rows x 2 vertical columns are opened at equal intervals on the side surface on the side having a length of 180 mm, and these windows have a rectangular cross section of 1.0 × 0.3 mm. A 1.5 m long pumping light introducing fiber (numerical aperture 0.2) is connected. One end of the side not connected to the container of the excitation light introducing fiber are each wavelength 0.8 [mu] m, attached via a laser Zada diode and the optical lens output 100W. A reflection mirror having a reflectivity of 99.9% was pressed vertically on one end face of the laser fiber, and the other end face was left as a fractured surface (reflectance of about 4%). A total of 2 kW of pumping light was introduced, and laser oscillation with a wavelength of 1.05 μm of 0.5 kW was confirmed from the end face of the fracture surface of the laser fiber.
[0043]
Next, a second embodiment will be described with reference to FIG.
FIG. 3 is a configuration diagram of the laser beam generator 10 according to the second embodiment.
The laser light generator 10 of this embodiment includes a laser fiber 11 that is a single non-quartz optical fiber, a separator 12 that smoothes the flow of matching oil, a reflection mirror 13, an excitation light LD 14 that introduces excitation light, and a surface. The metal base 15 is subjected to specular gold plating, the matching oil introduction part 17 introduces matching oil into the metal base 15, and the matching oil discharge part 16 discharges the matching oil from the metal base 15.
[0044]
A cylindrical space is provided inside the metal substrate 15, and the laser fiber 11 is arranged in a spiral shape from the outer periphery to the center of the cylinder. A reflection mirror 13 is attached to the end face of the laser fiber 11 that is positioned at the center of the spiral, and the other end of the laser fiber 11 is drawn out of the metal substrate 15. Since the configuration of the laser fiber 11 is the same as that of the first embodiment, the description thereof is omitted.
[0045]
On the laser fiber 11 disposed inside the metal substrate 15, a separator 12, which is a coreless fiber obtained by removing a doped core from the laser fiber 11, is disposed in a spiral shape having no termination at the center point. 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, since the material of the separator 12 is the same as that of the non-quartz glass cladding described in the first embodiment, and the refractive index of the light is substantially equal to that of the matching oil, the separator 12 does not hinder the progress of the excitation light. .
[0046]
A plurality of excitation lights LD14 are arranged on the side surface of the cylinder inside the metal substrate 15, and the excitation light is introduced into the cylinder.
The introduced excitation light excites the laser fiber 11 while repeating reflection 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 taken out from the other end of the laser fiber 11.
[0047]
[Example 2]
In the second embodiment, a laser fiber doped with 5 at% Er ³⁺ ions in the core of an AlF ₃ —ZrF ₄ glass fiber having a core diameter of 100 μm, a cladding diameter of 125 μm, and a numerical aperture of 0.2 has an outer diameter of 100 mmφ. It was housed in a casing made of a metal plate that was spirally (one layer) plated with gold. Then, a coreless (single layer) AlF ₃ —ZrF ₄ 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 matching oil. Since this separator is made of the same material as the cladding of the laser fiber, it is optically identical when immersed in matching oil and does not obstruct the progression of the excitation light. A matching oil inlet and outlet for flowing matching oil were provided near the end face of the separator, and matching oil having a refractive index of 1.448 was allowed to flow at a rate of 0.1 liter / min. The excitation light was applied by a pulsed laser diode with an oscillation wavelength of 0.98 μm arranged around the disk, and an average of 500 W was input. One end face of the laser fiber was pressed with a mirror having a reflectance of 99%, and the other end face was left as a broken surface. As a result, it was confirmed that pulse laser oscillation in the wavelength 2.8 μm band with an average of 50 W and a repetition of 100 Hz was achieved.
[0048]
Next, a third embodiment will be described with reference to FIG.
FIG. 4 is a configuration diagram of the laser beam generator 20 according to the third embodiment.
The laser light generator 20 includes a laser fiber 21 that is a single non-quartz optical fiber, a reflection mirror 22, an inner structure 23f, an outer structure 23e, a metal casing 23, a matching oil introduction part 23b, and a matching oil discharge. It is comprised by the separate fibers 23c and 23d which make the part 23a and the flow of matching oil smooth.
[0049]
The inside of the metal housing 23 is gold-plated and has a cylindrical outer structure 23e inside thereof. Inside the outer structure 23e, a cylindrical inner structure 23f smaller of its bottom radius than the outer structure 23 e is disposed surrounded by the side surfaces and the outer structure 23e of the inner structure 23f The space above and below is sealed by covering with a plate having a transparent fluororesin layer on the surface of the gold plating layer. Both the inner structure 23f and the outer structure 23e are made of a transparent fluororesin, and the inner structure 23f is subjected to gold plating on the inner side surface.
[0050]
The laser fiber 21 is disposed in a space surrounded by the side surface of the inner structure 23f and the side surface of the outer structure 23e by being wound around the side surface of the inner structure 23f a plurality of times. Drawn outside. A 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 with a broken surface.
[0051]
A matching oil introduction part 23b and a matching oil discharge part 23a are arranged in the upper part of the space surrounded by the side surface of the inner structure 23f and the side surface of the outer structure 23e, and the matching oil is circulated inside the space.
[0052]
In addition, a plurality of separate fibers 23c and 23d are arranged inside this space. The separate fibers 23c and 23d are arranged in the direction perpendicular to the bottom surface of the metal housing 23 outside the laser fiber 21 wound around the side surface of the inner structure 23f. Each of the separate fibers 23c and 23d has the same thickness as the gap between the side surface of the inner structure body 23f and the side surface of the outer structure body 23e. Form a flow path.
[0053]
Among the plurality of separate fibers 23c and 23d, the separate fiber 23c disposed between the matching oil introduction part 23b and the matching oil discharge part 23a has a length that is equal to the height of the inner structure 23f and the outer structure 23e. The area where the matching oil introduction part 23b is connected and the area where the matching oil discharge part 23a is connected are divided.
[0054]
Otherwise, the length of the separate fiber 23d is shorter than that of the separate fiber 23c, and the matching oil passes through the gap formed thereby. One end of each of the separate fibers 23d is disposed in contact with an upper surface or a lower surface of a space surrounded by the inner structure body 23f and the outer structure body 23e, and one separate fiber 23d is provided with the inner structure body 23f and the outer structure body 23e. Are disposed in contact with the lower surface of the space surrounded by the inner structure 23f and the outer structure 23e, and the separate fiber 23d disposed next to the upper surface of the space surrounded by The separate fiber 23d disposed next to the separate fiber 23d disposed in contact with the lower surface of the space surrounded by the inner structure 23f and the outer structure 23e is surrounded by the inner structure 23f and the outer structure 23e. It is arranged in contact with the upper surface of the space. By arranging the separate fiber 23d in this way, the matching oil flows while moving up and down the side surfaces of the inner structure body 23f and the outer structure body 23e.
[0055]
Here, the separate fibers 23c and 23d are made of the same material as the non-quartz glass clad described in the first embodiment, and the refractive index of light is substantially equal to that of the matching oil. Absent.
[0056]
The excitation light is emitted from the upper part of the space surrounded by the inner structure 23f and the outer structure 23e, and the irradiated excitation light excites the laser fiber 21 while being repeatedly reflected in the space, and is thereby generated. The laser light is extracted from one end of the laser fiber 21 to which the reflection mirror 22 is not attached.
[0057]
[Example 3]
In the third embodiment, a laser fiber doped with 0.4 at% Dy ³⁺ ions in the core of a Ga—Na—S glass fiber having a core diameter of 50 μm, a cladding diameter of 125 μm, and a numerical aperture of 0.2 is used as the outer periphery. One layer was wound around the side surface of a 100 mmφ cylinder. This cylinder is formed of a transparent fluorine resin, and the inside thereof is gold-plated. And as shown in FIG. 4, the coreless (single layer) Ga-Na-S type | system | group glass fiber of thickness 100 micrometers was arrange | positioned as a separator on the outer side of the wound laser fiber. This fiber serves to smooth the flow of matching oil. This separator is made of the same material as the clad of the laser fiber, and when immersed in the matching oil, it optically becomes the same as the clad and the matching oil. A transparent fluororesin having an inner diameter of 100.30 mm and a thickness of 0.5 mm is disposed on the outer side of the structure thus combined. The outside was covered with a metal mold having a mirror surface of a split mold inner surface gold. An inlet and outlet for flowing the matching oil were provided at the top of the cylinder, and a matching oil having a refractive index of 2.14 was allowed to flow at a rate of 0.1 liter / min. Excitation light was performed by a laser diode having an oscillation wavelength of 0.8 μm arranged around the cylinder, and a total of 2.5 kW was input. One end surface of the laser fiber was pressed with a mirror having a reflectance of 99% against light having a wavelength of 3.3 μm, and the other end surface was left as a broken surface. As a result, it was possible to confirm laser oscillation of 150 W wavelength in the 3.3 μm band.
[0058]
Next, a fourth embodiment will be described with reference to FIG.
FIG. 5 is a configuration diagram of a laser beam generator 30 according to the fourth embodiment.
The laser light generating device 30 of this embodiment includes a continuous laser fiber 31, a matching oil introducing portion 32, optical ducts 33a and 33b for introducing excitation light into the laser fiber 31, a matching oil discharging portion 34, a reflecting mirror 35, and a surface. It is composed of gold wires 37a and 37b processed with transparent fluororesin, and a metal substrate 36 whose surface is gold-plated and whose surface is further processed with transparent fluororesin.
[0059]
The laser fibers 31 are arranged in a plane in the metal substrate 36 while being folded back at a plurality of locations, and the two ends of the rows of the laser fibers 31 arranged in a plane in the metal substrate 36 are parallel to the laser fibers. Lines 37a and 37b are arranged.
[0060]
Two optical ducts 33 a and 33 b are disposed on the laser fiber 31 disposed in the metal substrate 36, and excitation light is introduced into the laser fiber 31 through these optical ducts 33 a and 33 b. The laser fiber 31, the gold wires 37 a and 37 b, and the optical ducts 33 a and 33 b arranged in the metal base 36 are gold-plated on the surface, and a plate whose surface is processed with transparent fluororesin is used as the metal base 36. By covering, it is accommodated in the metal substrate 36. 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 gold-plated on the gold wires 37a and 37b, the metal substrate 36, and the surface, and further the surface thereof. Is surrounded by a transparent fluororesin processed plate, and the portions other than the matching oil introduction portion 32 and the matching oil discharge portion 34 are sealed.
[0061]
Matching oil is introduced from the matching oil introduction section 32, and the introduced matching oil flows while filling the laser fiber 31 disposed in the metal base 36 and is discharged from the matching oil discharge section 34.
[0062]
The excitation light is introduced into the optical ducts 33 a and 33 b, and the excitation light introduced into the optical ducts 33 a and 33 b is introduced into the laser fiber 31 in the metal substrate 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 taken out from there. The laser beam reaching the side where the reflection mirror 35 is disposed is reflected there and taken out from the end face where the reflection mirror 35 is not installed.
[0063]
[Example 4]
In the fourth embodiment, 1.0 at% Nd ³⁺ ions and 0.01 at% Ce ³ are placed inside the core of an AlF ₃ fluoride glass fiber having a core diameter of 50 μm, a cladding diameter of 125 μm, and a numerical aperture of 0.2. ⁺ Laser fibers that are co-doped with ions and have a total length of 200 × 25 mm in width are densely arranged in a flat plate shape while being folded back. The substrate is a flat plate with a mirror-finished gold surface, and a transparent fluororesin film with a thickness of 0.01 μm is uniformly applied, and the laser is arranged at both ends of the array of laser fibers arranged in a plane on the substrate. A 200 μm pure gold wire with a thin transparent fluororesin coating was placed in parallel with the fiber.
[0064]
And the metal plate which apply | coated 0.01 mm transparent fluororesin on the mirror surface gold plating surface which has the window for introducing excitation light into an optical duct was covered on the laser fiber arranged in the board | substrate.
[0065]
Here, since the confidentiality of both end portions is enhanced by the pure gold wires arranged at both end portions of the laser fiber, the matching oil can be flowed at a strong pressure. A mask that reflects a laser beam having a wavelength of 1.05 μm is placed so as to cross the entire fiber alignment portion at right angles, and an excimer laser (wavelength 256 nm) is irradiated on the mask to induce a change in the refractive index of the laser. A chirped grating was formed inside the core of the fiber. This chirped grating corresponds to multimode mode dispersion, and lowers the transmittance in the vicinity of a wavelength of 1.05 μm in each mode. As a result, the amplified spontaneous emission around the wavelength of 1.05μm is suppressed, allowing vibration lasers originated wavelength 1.33.
[0066]
A matching oil having a refractive index of 1.432 is allowed to flow from the matching oil introduction portion at a rate of 0.1 liter / minute, and a total of 2.8 kW is input through an optical duct in which excitation light from a laser diode having an oscillation wavelength of 0.8 μm is disposed. did. One end surface of the laser fiber was pressed against a mirror having a reflectance of 99%, and the other end surface was left as a broken surface. As a result, it was possible to confirm laser oscillation in a wavelength 1.33 μm band of 0.5 kW.
[0067]
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 that is a single non-quartz optical fiber, a winding drum 52 around which the laser fiber 51 is wound, a pumping light introducing fiber 53, a matching oil introducing unit 54, a matching oil discharging unit 55, and a bundle unit. 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.
[0068]
The laser fiber 51 is folded at a plurality of locations and bundled in the bundle portion 57. The folded portion of the laser fiber 51 is wound and fixed around a winding drum 52 located at both ends of the bundle portion. Both end faces of the laser fiber 51 are arranged with a broken surface.
[0069]
The ends of a plurality of excitation light introducing fibers 53 are arranged at both ends of the bundle portion 57 in the longitudinal direction of the laser fiber 51, and the excitation light is introduced into the bundle portion 57.
[0070]
A partition wall 59 is attached to the central portion of the bundle portion 57 in the longitudinal direction so as to sandwich the bundle portion 57, and an O-ring 58 is attached to the outside of the partition wall 59.
[0071]
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 arranged in this way are housed in a box-shaped metal jig 60. The upper part is covered with a plate whose interior is gold-plated and whose surface is covered with transparent fluororesin.
[0072]
At this time, both end portions of the laser fiber 51 and the end surface portion on the side not connected to the bundle portion of the excitation light introducing fiber 53 are arranged outside the metal jig 60. The partition wall 59 divides the inside of the metal jig 60 into two regions, and the O-ring 58 increases its confidentiality. The matching oil introduction part 54 is connected to one area divided by the partition wall 59, and the matching oil discharge part 55 is attached to the other area.
[0073]
FIG. 7 is a cross-sectional view taken along line AA of the bundle portion 57 in 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. The laser fiber 51 includes a doped core 51a and a non-quartz glass cladding 51b, and has a coaxial structure with the doped core 51a as the center and the non-quartz glass cladding 51b as an outer periphery.
[0074]
The outer wall portion of the bundle part is constituted by a mirror gold-plated metal jig 57b that has been subjected to mirror gold plating and a transparent fluororesin clad 57a that covers the surface of the mirror gold-plated part of the mirror gold-plated metal jig 57b. It is structured to reflect within the captured excitation light bundle part.
[0075]
Here, it is assumed that the non-quartz glass cladding 51b and the matching oil 61 have substantially the same refractive index, and the doped core 51a has a higher refractive index than the non-quartz glass cladding 51b and the matching oil 61. The light refractive index 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.
[0076]
FIG. 8 shows a detailed view of a portion B in FIG.
The tip of the pumping light introducing fiber 53 is disposed in the portion B, and the pumping light is introduced into the laser fiber 51 by irradiating the pumping light from the tip of the pumping light introducing fiber 53. As the excitation light introducing fiber 53, a fiber having a relatively large diameter or a band-like fiber having a good coupling with a commercially available high-power laser diode is used.
[0077]
In FIG. 8, θp indicates the total reflection critical angle of the excitation light introducing fiber 53, and the excitation light irradiated from the excitation light introducing fiber 53 spreads at an angle of 2 × (90−θp). The light is introduced into the laser fiber 51.
[0078]
θb represents the total reflection critical angle in the matching oil 61 and the transparent fluororesin clad 57a, and the excitation light that has reached the transparent fluororesin clad 57a within the total reflection critical angle θb is transmitted through the transparent fluororesin clad 57a. It is totally reflected and confined inside the transparent fluororesin clad 57a.
[0079]
In order to increase the efficiency of introducing the pumping light, the part B, which is the pumping light introducing part, has the laser fiber 51 and the transparent fluororesin cladding 57a spread. In the case of FIG. The fluororesin clad 57 a has a spread with an angle of θt to the outside with respect to the central axis of the bundle portion 57.
[0080]
Here, it is desirable that all the excitation light introduced from the excitation light introduction fiber 53 into the laser fiber 51 is totally reflected by the transparent fluororesin clad 57a and introduced into the bundle portion 57. The angle formed by the excitation light irradiated from the introduction fiber 53 and the surface of the transparent fluororesin clad 57a needs to be not more than the total reflection critical angle θb. The angle between the excitation light irradiated from the excitation light introducing fiber 53 and the surface of the transparent fluororesin clad 57a is the largest because the excitation light irradiated from the excitation light introducing fiber 53 is the bundle portion described above. This is the time when the transparent fluororesin clad 57a having an angle θt spreads outward with respect to the central axis 57, and the excitation light irradiated from the excitation light introducing fiber 53 at that time and the surface of the transparent fluororesin clad 57a. Is expressed by (θp + θt). Therefore, the spread of the laser fiber 51 and transparent fluororesin clad 57a in the B part is configured such that the spread angle θt to the outside of the B part satisfies (θp + θt) <θb.
[0081]
Next, the operation of the optical signal amplifier 50 will be described with reference to FIG.
The matching oil introduced from the matching oil introducing portion 54 sees one region branched by the partition wall 59 and then flows inside the bundle portion 57 to reach the other region branched by the partition wall 59. Thereafter, the matching oil fills that region and is discharged from the matching oil discharge portion 55.
[0082]
Excitation light introduced from the excitation light introducing fiber 53 while being repeatedly reflected within the bundle 57 reaches the doped core 51a of the fiber laser 51, the laser fiber 51 which excitation light is irradiated introduced from one end of the array Zafu Aiba 51 Amplifies the received signal light. Then, the amplified signal light is taken out from the other end face.
[0083]
[Example 5]
In the fifth embodiment, a laser in which 5000 ppmwt Er ³⁺ ions and 5 wt% Yb ³⁺ ions are co-doped in the core of a multicomponent aluminosilicate glass fiber having a core diameter of 10 μm, a cladding diameter of 125 μm, and a numerical aperture of 0.11. The fiber fiber-doped laser fiber was folded so that the bundle part length was 250 mm. By using a fiber having a total length of 230 m and setting the number of bundle folds to 452 times, the length per round trip of the fiber was set to 1000 mm. A total of 10 pumping light introducing fibers each having a rectangular cross section of 10.0 × 0.1 mm were inserted into both end faces of the bundle part, and surrounded by a metal jig with a partition wall attached to the center. The metal jig was made of brass, and its surface was subjected to a mirror pure gold plating process, and the surface was covered with a transparent fluorine resin having a refractive index of 1.34.
[0084]
A transparent fluorine resin having a refractive index of 1.34 was applied to a portion of the laser fiber that protruded beyond the pumping light introducing portion, and a transparent ultraviolet curable resin having a refractive index of 1.445 was applied to the pumping light introducing fiber.
[0085]
The laser main body configured as described above was housed in a metal casing. At this time, the inside of the metal casing was divided into two regions by the partition of the laser body. A matching oil introduction part is installed in one area, and a matching oil discharge part is installed in the other area. Then, the matching oil introduction part was connected to an oil circulation pump, transparent matching oil having a refractive index of 1.523 was poured into the casing, and the matching oil was circulated so as to pass through the laser bundle part under pressure. The pressure here was 3 kg / cm ² . The fiber take-out part was tightly sealed with resin to prevent the pressure from taking out from inside the housing. A signal light having a wavelength of 1.53 to 1.57 μm can be simultaneously incident on one end of the laser fiber at 40 wavelengths. The other end face is connected with the extraction quartz Fiber signal light at an oblique fracture connection.
[0086]
The pumping light introducing fiber is coupled to a semiconductor laser having an oscillation wavelength of about 0.98 μm and a maximum output of 50 W through a cylindrical lens, and pumping light is introduced into the bundle portion. The intensity of the introduced signal light reached a total of 6 dBm, and the output of the amplified signal light reached a total of 55 dBm. At this time, no laser damage was observed by the pumping laser of the matching oil. Further, the amplification deviation between wavelengths could be suppressed to ± 1 dB or less by adjusting the excitation light intensity.
[0087]
In the above description, the cross-sectional shape of the laser fiber has been described as a circular shape and a quadrangular shape. However, other shapes of the laser fiber may be used, and a rectangular shape, a D shape, or a barrel shape is preferable in terms of efficiency.
[0088]
In the first, second, third, fourth, and fifth embodiments, each configuration has been described as a laser beam generator. However, in each configuration, it is used as an optical signal amplifier by removing the reflection mirror. It is good to do.
[0089]
Furthermore, 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.
[0090]
【The invention's effect】
Since the laser beam generator of the present invention accommodates a sufficiently long optical fiber and a fluid medium having substantially the same refractive index as the outer peripheral portion of the non-quartz optical fiber in the excitation light reflecting portion, it is easy to manufacture, An efficient laser beam generator can be realized.
[0091]
Further, since the fluid medium is caused to flow, deterioration of the fluid medium due to heat generation or the like and deterioration of the non-quartz optical fiber can be suppressed, and a laser light generator with high light resistance can be realized.
[0092]
In the optical signal amplifier of the present invention, the pumping light reflecting part accommodates a fluid medium having substantially the same refractive index as the outer peripheral part of the optical fiber and a sufficiently long non-quartz optical fiber. A good optical signal amplifier can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a laser beam generator according to a first embodiment.
FIG. 2 is an enlarged cross-sectional view showing the inside of the fiber storage box 4;
FIG. 3 is a configuration diagram of a laser beam generator according to a second embodiment.
FIG. 4 is a configuration diagram of a laser beam generator in a third embodiment.
FIG. 5 is a configuration diagram of a laser beam generator in a fourth embodiment.
FIG. 6 is a configuration diagram of a laser beam generator according to a fifth embodiment.
7 shows an AA cross-sectional view of the bundle portion in FIG. 6. FIG.
FIG. 8 shows a detailed view of a portion B in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser beam generator 2 Laser fiber 3 Excitation light introduction fiber 4 Fiber storage box 4a Matching oil introduction port 4b Matching oil discharge port 5 Reflecting mirror 6 Matching oil

Claims (10)

In a laser light generator for generating laser light by supplying excitation light to a laser active substance,
And said laser active material, possess an outer peripheral portion made of a material of non-silica-based covering the laser active material, the optical fiber 1 connection juxtaposed longitudinally at a plurality of positions by disposing a predetermined gap,
A fluid medium having a refractive index at the wavelength of the excitation light substantially equal to that of the outer peripheral portion;
A pumping light reflecting section for containing at least a part of the optical fiber and confining the pumping light by filling the gap with the fluid medium ; and
An excitation light introducing section for introducing the excitation light into the excitation light reflecting section;
Have
The optical fiber is arranged in a spiral shape, and the gap is made of the same material as the clad of the optical fiber, and a separator that forms a flow path of the flowable medium is provided. A laser beam generator.   2. The laser beam generator according to claim 1, wherein the fluid medium is a cooling medium that cools the optical fiber and the excitation light introducing section. The laser active materials include Nd ³⁺ , Yb ³⁺ , Er ³⁺ , Pr ³⁺ , Ce ³⁺ , Tm ³⁺ , Ho ³⁺ , Tb ³⁺ , Dy ³⁺ , Eu ³⁺ , Eu ²⁺ and 2. The laser beam generator according to claim 1, wherein the laser beam generator is at least one substance selected from organic dyes.   The optical fiber includes fluoride glass fiber, fluorophosphate glass fiber, chalcogenide glass fiber, oxychalcogenide glass fiber, phosphate glass fiber, tellurite glass fiber, borate glass fiber, multicomponent aluminosilicate glass fiber or plastic fiber. The laser beam generator according to claim 1, wherein at least one type of the laser beam generator is used. In a laser light generator for generating laser light by supplying excitation light to a laser active substance,
^{Yb 3+, Er 3+, Ce 3+} , Tm 3+, possess at least one laser active substance selected from Ho ^3+, and a peripheral portion made of a material of silica-based covering the laser active material, A series of optical fibers arranged in a longitudinal direction at a plurality of locations with a predetermined gap ;
A fluid medium having a refractive index at the wavelength of the excitation light substantially equal to that of the outer peripheral portion;
A pumping light reflecting section for containing at least a part of the optical fiber and confining the pumping light by filling the gap with the fluid medium ; and
An excitation light introducing section for introducing the excitation light into the excitation light reflecting section;
Have
The optical fiber is arranged in a spiral shape, and the gap is made of the same material as the clad of the optical fiber, and a separator that forms a flow path of the flowable medium is provided. A laser beam generator.   6. The laser beam generator according to claim 5, wherein the fluid medium is a cooling medium that cools the optical fiber and the pumping light introducing section. In an optical signal amplifier that amplifies signal light by supplying excitation light to a laser active substance,
And said laser active material, possess an outer peripheral portion made of a material of non-silica-based covering the laser active material, the optical fiber 1 connection juxtaposed longitudinally at a plurality of positions by disposing a predetermined gap,
A fluid medium having a refractive index at the wavelength of the excitation light substantially equal to that of the outer peripheral portion;
A pumping light reflecting section for containing at least a part of the optical fiber and confining the pumping light by filling the gap with the fluid medium ; and
An excitation light introducing section for introducing the excitation light into the excitation light reflecting section;
Have
The optical fiber is arranged in a spiral shape, and the gap is made of the same material as the clad of the optical fiber, and a separator that forms a flow path of the flowable medium is provided. An optical signal amplifier.   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 introducing section.   The optical fiber includes fluoride glass fiber, fluorophosphate glass fiber, chalcogenide glass fiber, oxychalcogenide glass fiber, phosphate glass fiber, tellurite glass fiber, borate glass fiber, multicomponent aluminosilicate glass fiber or plastic fiber. The optical signal amplifier according to claim 7, wherein the optical signal amplifier is at least one of the types.   6. The laser beam generator according to claim 1, wherein the optical fiber is folded and bundled at a plurality of locations.

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