JPH04342182A - Laser system - Google Patents

Abstract

PURPOSE:During the acquisition of either an oscillated laser beam or a wavelength converted oscillated laser beam through an optical fiber, to allow the beam to be very efficiently obtained by way of an optical fiber having a small diameter without a substantial loss, and the beam thus obtained to be easily converged into a microspot having a high energy density. CONSTITUTION:A phase-conjugate light emitting element 20 which possesses a light refracting property, and is made up of a non-linear medium, is positioned within a cavity resonator system 10 in a round-trip optical path of an oscillated laser beam or a wavelength converted oscillated laser beam. Moreover, one end 31 of an optical fiber is disposed adjacently to the phase-conjugate light emitting element. A phase conjugate light is produced by the use of, as a pumping beam, the oscillated laser beam or the wavelength converted oscillated laser beam, wherein the light is transmitted accurately in a reversed direction along the optical path of a guide beam which is incident on the phase-conjugate light emitting element 20 from the end of the fiber. The phase conjugate light thus produced is injected into the end 31 of the optical fiber with a high energy density, and then acquired from the other end 32 of the optical fiber.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention utilizes oscillated laser light or laser light whose wavelength is converted into second harmonics, etc., at high energy density through a small diameter optical fiber for purposes such as material processing and medical treatment. The present invention relates to a laser device that can be taken out.

0002

[Prior Art] Gas or solid-state laser devices are used in a wide range of fields such as measurement, medical care, material processing, and the chemical industry. Fiber is often used. For example, in the field of material processing using YAG lasers, optical fibers are widely used to guide laser light to the workpiece.
Furthermore, in the medical field, treatment is often performed by guiding laser light to an affected area via an optical fiber. As is well known, the advantage of optical fibers is that they allow laser light to be sent freely into narrow or intricate spaces, and they are much cheaper than light guide paths that combine optical components such as mirrors and lenses. has great appeal.

[0003] As described above, many application fields in which laser light is guided through optical fibers require high-energy density laser light, but the laser light emitted from the optical fiber can be used for material processing or medical purposes using lenses, etc. When condensing light, the smaller the diameter of the output end of the optical fiber, the smaller the condensed beam diameter and the higher the energy density, so it is required to use an optical fiber with as small a diameter as possible.

In order to guide laser light through such a small-diameter optical fiber, it is first necessary to inject the laser light generated by a laser device into the end of the optical fiber at high density. Of course, the diameter of the optical fiber is much larger than that of the optical fiber. For this reason, conventionally, a nearly parallel laser beam output from a laser device is received by optical means such as a lens, the beam diameter is narrowed down to the diameter of the optical fiber, and the end of the optical fiber is placed at the focal point. Usually, laser light is focused and injected at high energy density.

[0005]

[Problem to be Solved by the Invention] However, in the recent field of laser applications, it has become necessary to increase the energy density of laser light transmitted through optical fibers, and the diameter of optical fibers has been reduced accordingly. This has made it difficult to focus the laser beam onto a small spot and align it with the end of the optical fiber.

That is, although the laser beam is almost parallel, there is always a slight divergence angle θ, and the minimum diameter of the spot that can condense the laser beam is generally given by the following equation. d=f·θ where f is the focal length of the condenser lens. As can be seen from this, in order to reduce the spot diameter d, it is sufficient to reduce θ and f, but in the multi-mode oscillation of a normal laser device, the limit for the divergence angle θ is about 5 mrad, and the focal length f If it is made too small, the spherical aberration of the lens will increase, and the spot diameter will become larger. Now, let us assume that the focal length f of this condensing lens is 10
0 mm, and the divergence angle θ of the laser beam is 5 mrad, the diameter d of the focused spot is 500 μm, which is considerably larger than the diameter of the optical fiber required for high energy density transmission as described above.

To solve this problem, it is possible to make the laser device oscillate in a single mode to reduce the divergence angle θ of the laser beam, or to shorten the focal length f of the condensing lens by using a combination lens. Not only are laser devices and condensing lenses becoming sophisticated and very expensive, but it is also difficult to align the minute spot with the end of the optical fiber, and this adjustment is delicate, causing vibrations and vibrations during use. There is also a practical problem in that it is more likely to become distorted when subjected to impact.

In order to solve these problems, the present invention aims to provide a laser device suitable for extracting laser light or its wavelength-converted light at high energy density through a small-diameter optical fiber so that it can be focused on a minute spot. shall be.

[0009]

[Means for Solving the Problems] In the first invention of the present application, in which the oscillated laser light is extracted from a laser device via an optical fiber, there is provided a laser resonant system and a laser beam inserted into the reciprocating optical path of the laser light within this resonant system. A phase conjugate light generating element made of a nonlinear medium, and an optical fiber having one end located near this element are provided, and the laser light passing through the phase conjugate light generating element and reciprocating within the laser resonant system is used as pumping light, and the optical fiber is The laser beam that enters the element from one end is used as a guide light to generate phase conjugate light, and the laser beam as the phase conjugate light is reciprocated between this and the other end of the optical fiber using the element as a phase conjugate mirror. By taking out the part from this other end, the above-mentioned objective is achieved.

As the nonlinear medium for the above-mentioned phase conjugate light generating element, it is preferable to use, for example, a barium titanate crystal which exhibits an electro-optic effect such as a photorefractive effect or a Bockels effect, and in this case, a laser resonant system 1000n
It is preferable to use a laser oscillation system using a laser medium of argon gas, for example, which oscillates a laser beam with a wavelength of approximately m. Further, it is preferable to interpose an optical system such as a lens between the phase conjugate light generating element and one end of the optical fiber so that laser light from one end is condensed onto the other end.

[0011] Furthermore, the second aspect of the present invention extracts the wavelength-converted light of the oscillated laser light from the laser device via an optical fiber.
According to the invention, a first resonant system including a laser medium, a nonlinear optical crystal that is inserted into the first resonant system and converts the wavelength of the oscillated laser light, and a first resonant system and the nonlinear optical crystal. It consists of a second resonant system for wavelength converted light that shares a portion including a non-linear medium inserted in the round trip optical path of the wavelength converted light in the non-shared portion of the second resonant system with the first resonant system. A phase conjugate light generating element and an optical fiber having one end located near this element are provided, and the wavelength-converted light that passes through the phase conjugate light generating element and reciprocating within the second resonant system is used as pumping light, and the optical fiber is Wavelength-converted light that enters this element from one end is used as a guide light to generate its phase conjugate light, and this phase-conjugated wavelength-converted light is made to travel back and forth between the other end of the optical fiber using the element as a phase conjugate mirror. By taking out the part from this other end, the aforementioned object is achieved.

[0012] In this second invention, it is particularly advantageous to use the wavelength-converted light as the second harmonic light of the oscillation laser light within the first resonant system, and nonlinear optical crystals for such wavelength conversion include, for example, Potassium titanate phosphate crystals are preferably used. When using the above-mentioned barium titanate crystal as a phase conjugate light generating element, it is appropriate that the first resonant system is a laser oscillation system using a solid laser medium such as YAG that emits laser light with a wavelength of about 500 nm. . Also, in the case of the second invention, an optical system such as a lens is interposed between the phase conjugate light generating element and one end of the optical fiber to condense the wavelength-converted light from one end to the other. good.

Furthermore, in the second invention, a shutter is inserted between the phase conjugate light generating element and the reflection mirror on the non-shared part side of the first resonance system of the second resonance system, and this shutter is initially Finely adjust the position of the reflecting mirror in the open state to make the second resonance system resonate with the wavelength-converted light, then close the shutter and connect the phase conjugate light generating element to the optical fiber as a phase conjugate mirror. It is advantageous in implementing the second invention to make the wavelength-converted light go back and forth between the other end and the other end.

[0014]

[Function] In order to facilitate understanding, an outline of the principle of generation of phase conjugate light by the phase conjugate light generation element used in the first and second inventions of the present application will first be explained with reference to FIG. For a relatively simple explanation of this phase conjugate light, see Feinberg, What is the photorefractive effect? Parity Magazine,
Vol. 4, No. 7, July 1989 issue, Pepper, Applications of optical phase conjugation; Science magazine, 1986
Please refer to the March issue. Since the present invention utilizes the generation of phase conjugate waves by degenerate four-wave mixing, FIG. It is shown. Laser beams L1 and L2 travel in opposite directions and are usually called pumping beams, and laser beam L3 enters the phase conjugate light generating element 20 from a direction different from these.
Although this light is usually called a probe light, it will be called a guide light here because it plays the role of guiding or guiding the generation of the phase conjugate light L4.

When a nonlinear medium with a large third-order nonlinear optical constant, such as a barium titanate crystal, is irradiated with light, the crystal lattice is slightly distorted by the space charge induced inside by the optical electric field, which corresponds to the wavelength of the light. A periodic refractive index distribution occurs, which acts as a kind of diffraction grating for light and scatters it, producing a so-called photorefractive effect. Now consider the case where the pumping lights L1, L2 and the guide light L3 are incident on the phase conjugate light generating element 20 as shown in Fig. 2, and if the electric field vectors due to these are E1, E2 and E3, respectively, then E1=A1(r)exp [i(k1r −ω1t) ]
+c. c. E2=A2(r)exp[i(k2r−ω
2t) ] + c. c. E3=A3(r)exp[i(
k3r−ω3t) ]+ c. c. It is expressed as Here, A1(r), A2(r), A3(r) are the complex amplitudes of light, r is the position vector, i is the imaginary code, k1, k2, k
3 is the wave number vector of light, ω1, ω2, ω3 are the angular frequencies of light, t is time, c. c. is the complex conjugate term on each right-hand side.

In the generation of phase conjugate waves by degenerate four-wave mixing, as shown in FIG. 2, phase conjugate light L4 is generated using two pumping lights L1, L2 traveling in opposite directions and one guide light L3 as input lights. The guide light L3 has the role of guiding the phase conjugate light L4.
Pumping lights L1 and L2 each serve to excite this induction. To understand this situation, first let's look at three lights L.
1, L2, and L3, the third-order nonlinear polarization corresponding to the third-order nonlinear optical constant by the phase conjugate light generating element 20 in the product E1E2E3 of the three electric field vectors in the above equation expressing this. Pn is expressed as a function of position vector r and time t by the following equation. Pn(r,t) ∝A1(r)A2(
r) A3* (r) ・exp
[i{ (k1+k2+k3)r- (ω1 +ω2
−ω3)t }]+ c. c. However, A1, A2,
All A3* are scalar quantities, and A3* is the complex conjugate term of vector A3. In this formula, in the case of the present invention, ω1=
ω2=ω3=ω, and as can be seen from Figure 2, k1
Since +k2=0, the following equation is obtained. Pn(r,t) ∝A3* (r)exp[i(k3r
+ωt)]+c. c.

The phase conjugate light L4 is generated from the polarized wave expressed by the above equation, and its electric field vector E4 is given by the following equation. E4∝A3* (r)exp[i(k3r+ωt)]+
c. c. Now, this is expressed as the equation representing the electric field vector E3 of the guide light L3, E3=A3(r)exp[i(k3r-ωt)]+c
．． c. This corresponds to replacing time t with -t. In other words, the electric field vector E4 of the phase conjugate light L4 is the time reversal of the electric field vector E3 of the guide light L3, that is, E4 is an optical electric field that travels in the exact opposite direction of the path taken by E3, and in this sense, this electric field E4 The light L4 having the electric field E3 is called the phase conjugate light of the guide light L3 having the electric field E3.

Further, as can be seen from above, the phase conjugate light generating element 20 has the function of a mirror that reflects the guide light L3 as the phase conjugate light L4, and this is called a phase conjugate mirror. This phase conjugate mirror exhibits a unique behavior that differs from ordinary mirrors. That is, for example, when light traveling while diverging is reflected by a normal plane mirror, the reflected light naturally continues to diverge in the same way, but in the case of a phase conjugate mirror, the phase conjugate light L4 becomes the guide light L3 as described above. Because the reflected light travels in exactly the opposite direction of the path it followed, the reflected light travels while converging in the opposite direction to the incident light.

Furthermore, phase conjugate light L4 due to degenerate four-wave mixing
Another point in which the phase conjugate mirror used for generation of the
The incident light, that is, the guide light L3 can be amplified. This means that the amplitude of the aforementioned nonlinear polarization Pn is A1A2A3
* This is because it is proportional to the product A1A2 of the amplitudes of the optical electric fields of the pumping lights L1 and L2, and in terms of energy, the energy of the pumping lights L1 and L2 is proportional to the phase conjugate light L.
This is because the transition will be made to step 4.

Furthermore, it is possible to operate a phase conjugate mirror by dividing a part of the incident light and using it as pumping light.A mirror that uses the incident light as pumping light in this way is called a self-pumping phase conjugate mirror. I'm here.

The present invention utilizes the above-mentioned phase conjugate light generation function of a nonlinear medium having a photorefractive effect and its properties as a phase conjugate mirror, and a phase conjugate light generating element made of this nonlinear medium. In the first invention, the oscillating laser light or the wavelength is inserted into the laser resonant system for the oscillated laser light, and in the second invention, the oscillating laser light or the wavelength is inserted into the second resonant system for the wavelength converted light. Converted light is applied as pumping light, and one end of an optical fiber is positioned near this element.

As a result, the pumping light is scattered as described above due to the optical refraction effect of the element, and a part of this scattered light enters the optical fiber from one end, is reflected at the other end, and then returns to the element. It enters as a guide light. The element receiving this operates as a phase conjugate mirror as described above,
Since phase conjugate light is generated by amplifying the guide light and sent back to one end of the optical fiber along a path that accurately traces the input path in reverse, this process is repeated thereafter. In this way,
The pumping light given to the phase conjugate light generating element is guided into the optical fiber as phase conjugate light from one end of the optical fiber, and a phase conjugate beam is formed between the element as a phase conjugate mirror and the other end of the optical fiber. Since the light and the guide light, which is its reflected light, travel back and forth, it is sufficient to extract a portion of these laser beams from the other end of the optical fiber.

As can be seen from this, in the present invention, the phase conjugate light guided from the phase conjugate light generating element toward the optical fiber accurately follows the incident path of the guide light in the opposite direction and is sent back to one end of the optical fiber. Even if the guide light is very thin, it is possible to inject all of the phase conjugate light that has amplified the guide light at a high energy density without wasting any waste. Furthermore, since the phase conjugate light is automatically guided to the optical fiber as described above due to the characteristics of the element as a phase conjugate mirror, in the present invention, one end of the optical fiber is simply placed in the vicinity of the phase conjugate light generating element. It is sufficient to position the laser beam and direct it almost toward the element so that the emitted guide light enters the element. This eliminates the need for precise positioning.

[0024]

[Embodiments] Hereinafter, embodiments of the invention of the present application will be described with reference to the drawings. Figure 1 shows an embodiment of a laser device according to the first invention that extracts oscillated laser light through an optical fiber, and Figure 3 shows an embodiment of the laser device according to the first invention.
1 and 2 respectively show examples of a laser device according to the second invention that extracts the wavelength-converted light. Although barium titanate is used as the phase conjugate light generating element in both embodiments, it is of course possible to appropriately use a nonlinear medium with a high photorefractive effect such as lithium niobate.

The laser resonant system 10 in FIG. 1 is a gas laser system, and consists of an argon laser tube 1 equipped with a discharge electrode 1a for excitation, and a pair of mirrors 2 and 3 sandwiching this from both sides, and emits a laser with a wavelength of 488 nm. It oscillates light L. In addition,
In a normal laser device, a partial reflection mirror is used on the extraction side of the laser beam L, but mirrors 2 and 3 in FIG. 1 are both total reflection mirrors. For the phase conjugate light generating element 20, a single crystal of barium titanate described above with a size of several mm is used, which is inserted into the laser resonant system 10, and the laser beam L is passed therein as pumping light back and forth.

The optical fiber 30 is connected to the laser resonant system 10 described above.
It is a small-diameter lens for extracting the laser beam L with high energy density from
The output laser beam Lo is placed near the phase conjugate light generating element 20 through the collimating lens 34 from the other end 32.
is retrieved via. Although the coupling lens system 33 is not necessary for extracting the phase conjugate light generated from the phase conjugate light generating element 20 as the output laser beam Lo, the guide light emitted from one end of the optical fiber 30 has a slight divergence angle. Therefore, this is intended to be efficiently injected into the phase conjugate light generating element 20. One end 31 of the optical fiber 30 on the inlet side of the laser beam L is preferably coated with a non-reflective coating for that wavelength, and the other end 32 on the output side is not coated at all or is partially reflective if necessary. A coating may be applied as appropriate. The collimating lens 34 converts the output laser beam Lo, which is extracted from the other end 32 and has a slight divergence angle, into a parallel light beam.
This is to make it easier to focus light onto a small spot using means such as a lens.

In the embodiment of FIG. 1 configured as described above, when the laser resonant system 10 including the laser tube 1 is initially oscillated, the laser beam L is scattered by the optical refraction effect of the phase conjugate light generating element 20. However, when a part of this scattered light enters the optical fiber 30 from one end 31 and is reflected at the other end 32 and returns to the phase conjugate light generating element 20, it is reflected as a phase conjugate mirror. As a result, phase conjugate light is generated by amplifying the returned incident light as a guide light and is injected into the optical fiber 30. By repeating this process, the light that travels back and forth within the optical fiber 30 in a short period of time is rapidly grow to.

At this time, the phase conjugate light injected into the optical fiber 30 is transmitted through the phase conjugate light generating element 2 as described in the section of operation.
0, the laser light L in the laser resonant system 10 is used as pumping light and its energy is converted into light of the same wavelength. fiber 30
You will be guided by Further, due to the function of the phase conjugate light generating element 20 as a phase conjugate mirror, this phase conjugate light is transmitted from one end of the optical fiber 30 to the coupling lens 3 in this example.
Since the guide light that enters it through 3 is generated so as to faithfully follow the path that it has followed in the opposite direction, all of the laser light L that is guided as phase conjugate light is transmitted very efficiently without leaking along the way. is injected into fiber 30.

In this manner, the guide light and the laser light L as the phase conjugate light reciprocate within the optical fiber 30 between the phase conjugate light generating element 20 as a phase conjugate mirror and the other end 32, so that one of them By taking out the part from the other end 32, the laser beam L oscillated by the laser resonant system 10 can be taken out with high energy density and much more efficiently than before through the thin optical fiber 30.

In the second embodiment of the invention shown in FIG.
The laser beam L oscillated in the resonant system 11 is converted by the nonlinear optical crystal 40 into wavelength-converted light Ls, which is the second harmonic thereof, and resonated in the second resonant system 12 to generate phase conjugate light. The wavelength-converted light Ls is extracted from the element 20 via the optical fiber 30 as an output laser light Lo.

In this embodiment, a solid YAG rod is used as the oscillation laser medium in the first resonant system 11, and is optically excited by an excitation light source 4a such as a xenon discharge lamp to oscillate laser light L at a wavelength of 1064 nm. This wavelength is caused to resonate between the total reflection mirrors 2 and 3. Also, this first
A deflection mirror 5 is inserted into the resonant system 11, and the optical path on the total reflection mirror 3 side is bent, for example, in the right angle direction as shown in the figure, and a nonlinear optical crystal 40 for wavelength conversion is inserted into this optical path. For example, a potassium phosphate titanate crystal is used as the nonlinear optical crystal 40, and the oscillated laser light L is converted into wavelength-converted light Ls having a wavelength of 532 nm, which is the second harmonic light, and is extracted downward through the deflection mirror 5. For this reason, the deflection mirror 5 is coated with a wavelength selective coating that is highly reflective for a wavelength of 1064 nm and non-reflective for a wavelength of 532 nm.

The second resonant system 12 is for this wavelength-converted light Ls, and is configured to share the optical path portion including the nonlinear optical crystal 40 of the first resonant system 11, and is taken out through the above-mentioned deflection mirror 5. The total reflection mirror 6 receives the wavelength-converted light Ls, and by finely adjusting its position, the distance between the total reflection mirror 3 shared with the first resonance system 11 and this total reflection mirror 6 is adjusted to the wavelength-converted light Ls. resonates. The same phase conjugate light generating element 20 as in the previous embodiment is inserted into the round trip optical path of the wavelength-converted light Ls in the part of the second resonant system 12 that is not shared with the first resonant system 11. In the example, a shutter 7 is inserted between the phase conjugate light generating element 20 and the total reflection mirror 6. This embodiment is the same as the previous embodiment in that one end 31 of an optical fiber 30 is located near the phase conjugate light generating element 20 via a coupling lens 33.

In the embodiment shown in FIG. 3 configured as described above, the total reflection mirror 6 is initially finely adjusted with the shutter 7 open to direct the second resonance system 12 to the wavelength-converted light Ls. Resonance is made so that the optimum mode for wavelength conversion by the nonlinear optical crystal 40 is obtained. The phase conjugate light generating element 20 in the second resonant system 12 uses the wavelength-converted light Ls as pumping light and guides it toward the optical fiber 30 and injects it into one end 31 of the optical fiber 30 as in the case of FIG. 32, in this embodiment, the wavelength-converted light Ls having a wavelength of 532 nm is extracted as the output laser light Lo.

When the shutter 7 is closed after the wavelength-converted light Ls is steadily guided to the optical fiber 30 via the phase conjugate light generating element 20 in this way, the light inside the second resonant system 12 is The wavelength-converted light Ls that was previously reflected by the total reflection mirror 6 is reflected by the phase conjugate light generating element 20 as a phase conjugate mirror, and is in the same state as before with the other total reflection mirror 3, i.e. The nonlinear optical crystal 40 resonates in the optimum mode for wavelength conversion. In the resonant state due to the fine adjustment of the total reflection mirror 6 mentioned above, this optimum mode is likely to collapse due to a slight deviation in its mechanical position, but in the resonant state due to the phase conjugate mirror, this mode is maintained very stably, so the laser The wavelength conversion efficiency from the light L to the wavelength-converted light Ls can be maintained high.

Note that in this state after the shutter 7 is closed, the phase conjugate mirror and the other end of the optical fiber 30 are in a resonant state with respect to the phase conjugate light, so that the phase within this so-called third resonant system is The conjugated light and the wavelength-converted light Ls in the second resonant system are coupled together, with one serving as pumping light for the other, and the phase conjugate light generating element 20 serving as the above-mentioned self-pumping phase conjugate mirror. As described above, in the second invention, by using the phase conjugate light generating element 20 as a kind of self-pumping phase conjugate mirror, the second resonance is generated so that the optimum mode for wavelength conversion by the nonlinear optical crystal 40 is stabilized. A resonant condition within the system 12 can be maintained.

[0036] Also, in this second invention, the second resonance system 1
It is exactly the same as in the first invention that the wavelength-converted light Ls in 2 can be efficiently injected into the thin optical fiber 30 via the phase conjugate light generating element 20 and extracted with high energy density.

The present invention is not limited to the embodiments described above, and the present invention can be implemented in various embodiments. For example, if one end 31 of the optical fiber 30 is brought closer to the phase conjugate light generating element 20, the coupling lens 33 can be omitted. Of course, the type and oscillation wavelength of the laser tube 1 and the solid-state laser medium 4, the material of the nonlinear optical crystal 40 for wavelength conversion, etc. should be appropriately selected depending on the type of nonlinear medium used as the phase conjugate light generating element 20.

[0038]

As described above, in the first invention of the present application, the reciprocating optical path of the laser beam within the laser resonant system, and in the second invention, the oscillation is performed by the nonlinear optical crystal inserted into the first resonant system containing the laser medium. By inserting a phase conjugate light generating element in each of the round trip optical paths in a second resonant system that resonates with wavelength-converted light obtained by converting the wavelength of a laser beam, and by positioning one end of an optical fiber near the second resonant system, phase conjugate light can be generated. The phase conjugate light of the guide light entering from one end of the optical fiber is generated in the opposite direction by using the laser light or wavelength-converted light reciprocating inside the light generating element as pumping light, and the phase conjugate light generating element is used as a phase conjugate mirror. By reciprocating the phase conjugate light and the guide light between the other end of the optical fiber and extracting a portion thereof, the following effects can be obtained.

(a) Since the phase conjugate light guided from the phase conjugate light generating element to the optical fiber accurately traces the incident path of the guide light in the opposite direction and is injected into one end of the optical fiber, the diameter of the optical fiber is small. Even if the guide light is thin, the energy of the pumping light can be used to amplify the guide light, and all the generated phase conjugate light can be wastefully injected into the optical fiber at high energy density and extracted from it. Laser light transmitted through such a small diameter optical fiber can be easily focused on a minute spot with extremely high energy density.

(b) Since the phase conjugate light is automatically guided to the optical fiber due to the characteristic of the phase conjugate light generating element as a phase conjugate mirror, the optical fiber is simply positioned with one end near the phase conjugate light generating element. To eliminate the need to precisely align the spot of a laser beam focused by a lens or the like with the end of a thin optical fiber as in the past, and to eliminate the risk of misalignment during use. Can be done.

(c) Even when the oscillation laser beam is wavelength-converted and then extracted through an optical fiber, the phase conjugate light generating element is used as a self-pumping phase conjugate mirror, making it optimal for wavelength conversion using a nonlinear optical crystal. The resonant state within the resonant system for wavelength conversion light can be maintained so that the mode is stabilized.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a laser device according to a first invention of the present application.

FIG. 2 is a schematic diagram of a phase conjugate light generating element and related laser light for explaining the principle of generating phase conjugate light in the invention of the present application.

FIG. 3 is a configuration diagram showing an embodiment of a laser device according to a second invention of the present application.

[Explanation of symbols] 1 Gas laser tube 4 Solid laser medium 10 Laser resonance system 11 First resonance system 1 for oscillation laser light
2 Second resonant system 20 for wavelength converted light
Phase conjugate light generating element 30 Optical fiber 31 One end of optical fiber 32 Other end of optical fiber 40 Nonlinear optical crystal L for wavelength conversion
Laser light or oscillation laser light Lo
Output laser beam Ls extracted via optical fiber
Wavelength converted light or second harmonic light L1
Pumping light L2 Pumping light L3 Guide light or probe light L4
phase conjugate light

Claims (5)

[Claims] 1. A laser device that extracts laser light through an optical fiber, comprising: a laser resonant system; and a phase conjugate light generating element comprising a nonlinear medium inserted in the reciprocating optical path of the laser light within the resonant system. , and an optical fiber with one end located near the element, the pumping light is laser light that passes through the phase conjugate light generating element and reciprocates within the laser resonant system, and the laser enters the element from one end of the optical fiber. A phase conjugate light is generated using light as a guide light, and a laser beam as a phase conjugate light is sent back and forth between the other end of the optical fiber using an element as a phase conjugate mirror, and a part of it is taken out from the other end. A laser device characterized by: 2. The laser device according to claim 1, wherein the laser resonance system is a laser oscillation system using a gas laser medium. 3. A laser device that extracts wavelength-converted laser light through an optical fiber, the laser device including a first resonant system including a laser medium, and a laser device that is inserted into the resonant system and converts the wavelength of the oscillated laser light. A second resonant system for wavelength converted light that shares a portion including the nonlinear optical crystal of the first resonant system with the nonlinear optical crystal, and a wavelength within a non-shared portion of the second resonant system with the first resonant system. It is equipped with a phase conjugate light generating element made of a nonlinear medium inserted in the round trip optical path of the converted light, and an optical fiber with one end located near this element, and a second resonance is generated through the phase conjugate light generating element. The wavelength-converted light that travels back and forth within the system is used as pumping light, and the wavelength-converted light that enters this element from one end of the optical fiber is used as guide light to generate its phase conjugate light. A laser device characterized in that a phase conjugate mirror is moved back and forth between the other end of an optical fiber and a part of the mirror is taken out from the other end. 4. The laser device according to claim 3, wherein the first resonant system is a laser oscillation system using a solid laser medium. 5. The laser device according to claim 3, wherein the wavelength-converted light is second harmonic light of the oscillation laser light within the first resonant system.