Optical resonator, component parts of the optical resonator, and laser device

Abstract

[Problem] To provide: an optical resonator capable of being compact even when a wavelength band-limiting element is disposed inside the optical resonator; a component for an optical resonator; and a laser device. [Solution] An optical resonator comprising: a laser medium disposed between a pair of reflective members and emitting emission light excited by a prescribed excitation light; and a wavelength band-limiting element disposed between the pair of reflective members, on the side that the emission light is emitted, said wavelength band-limiting element having two reflective planes that are orthogonal to the optical axis of the laser medium and limiting the wavelength band of the emission light. The wavelength band-limiting element is disposed at a position that suppresses the generation, between the reflective member on the laser beam emission-side and the wavelength band-limiting element, of a resonance component outside the target wavelength range for the wavelength band-limiting element.

Description

Technical Field

[0001] The present disclosure relates to an optical resonator, a component of the optical resonator, and a laser device.

Background Art

[0002] In recent years, various laser devices have been developed. For example, a passive Q-switch pulse laser device that changes the Q value with a passive element has been actively developed. In such a laser device, miniaturization has been progressing.

[0003] Also, for a wavelength band limiting element for narrowing the wavelength band of laser light, for example, an etalon element is used. However, since the etalon element is arranged obliquely with respect to the optical axis, it becomes difficult to miniaturize the optical resonator itself or the laser device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One aspect of the present disclosure provides an optical resonator, a component of the optical resonator, and a laser device that can be miniaturized even when a wavelength band limiting element is arranged in the optical resonator.

Means for Solving the Problems

[0006] In order to solve the above problems, in the present disclosure, a laser medium that is arranged between a pair of reflection members and emits emission light excited by predetermined excitation light, a wavelength band limiting element that is arranged on the emission light emission side between the pair of reflection members, has two reflection planes orthogonal to the optical axis of the laser medium, and limits the wavelength band of the emission light, are provided, The wavelength band limiting element is arranged at a position that suppresses the generation of resonance components outside the target wavelength range of the wavelength band limiting element between the reflection member on the emission side of the laser light and the wavelength band limiting element.

[0007] The wavelength band limiting element and the reflection member on the emission side of the laser light may be adjacent to each other.

[0008] The distance between the wavelength band limiting element and the reflection member on the emission side of the laser light may be within 50 microns.

[0009] A saturable absorber that is arranged between the laser medium and the wavelength band limiting element and whose transmittance increases with the absorption of the emitted light emitted from the laser medium may be further provided.

[0010] The space between the two reflection planes may be a saturable absorber whose transmittance increases with the absorption of the emitted light emitted from the laser medium.

[0011] A space layer may be provided between the laser medium and the wavelength band limiting element.

[0012] A space layer may be provided between the saturable absorber and the wavelength band limiting element.

[0013] The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and may be arranged in the optical resonator so as to have different transmittances for the emitted light in two polarization directions orthogonal to each other emitted from the laser medium.

[0014] The space between the two reflection planes is a saturable absorber whose transmittance increases with the absorption of the emitted light emitted from the laser medium. The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and may be arranged in the optical resonator so as to have different transmittances for the emitted light in two polarization directions orthogonal to each other emitted from the laser medium.

[0015] The two reflecting planes are saturable absorbers whose transmittance increases with the absorption of the emitted light emitted from the laser medium. The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and is arranged in the optical resonator so as to have different transmittances for the emitted light in two polarization directions orthogonal to each other emitted from the laser medium. A space layer may be provided between the laser medium and the wavelength band limiting element.

[0016] At least one of the pair of reflecting members is a polarization element, and the polarization element may have different reflectivities for the emitted light in polarization directions orthogonal to each other.

[0017] The plane on the emission side of the laser light of the two reflecting planes orthogonal to the optical axis may constitute the reflecting member on the emission side of the laser light of the pair of reflecting members.

[0018] The heat dissipation substrate disposed on the side opposite to the emission side of the laser light of the laser medium may be further provided.

[0019] The polarization element may be a photonic crystal composed of a periodic structure of an inorganic material.

[0020] The above optical resonator, An excitation light source unit that emits the excitation light to the laser medium, may be provided.

[0021] In order to solve the above problems, in the present disclosure, a saturable absorber whose transmittance increases with the absorption of the emitted light emitted from the laser medium, Two parallel reflecting plane portions formed on both side surfaces of the saturable absorber, are provided, and components of the optical resonator are provided.

[0022] In order to solve the above problems, in the present disclosure, a pair of reflecting members constituting the optical resonator, A wavelength band limiting element that is disposed on the side where the emitted light between the pair of reflecting members is emitted, has two reflecting planes orthogonal to the optical axis of the optical resonator, and limits the wavelength band of the emitted light. The plane on the side where the emitted light of the two reflecting planes orthogonal to the optical axis is emitted constitutes the reflecting member on the side where the emitted light of the pair of reflecting members is emitted, and components of the optical resonator are provided.

Brief Description of Drawings

[0023]

Figure 1

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Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of an optical resonator, components of the optical resonator, and a laser device will be described with reference to the drawings. In the following, the description will focus on the main components of the optical resonator, components of the optical resonator, and the laser device. However, there may be components and functions that are not shown or described in the optical resonator, components of the optical resonator, and the laser device. The following description does not exclude components and functions that are not shown or described.

[0025] (First Embodiment) With reference to FIG. 1, the configuration of the laser device according to this embodiment will be described. FIG. 1 is a diagram showing an example of the configuration of the laser device according to this embodiment. The laser device 1 is, for example, a passive Q-switch pulse laser device, and includes an excitation light source unit 2 and an optical resonator 4.

[0026] The excitation light source unit 2 emits excitation light 22 that excites the laser medium in the optical resonator 4. More specifically, the excitation light source unit 2 emits excitation light 22 having a wavelength near 808 [nm] that excites, for example, an Nd:YAG crystal, which is the laser medium. Also, if the excitation light source unit 2 can cause the excitation light 22 to enter the laser medium in the optical resonator 4, the excitation light source unit 2 may not include an optical system such as a lens.

[0027] The optical resonator 4 emits laser light excited by the excitation light 22 emitted by the excitation light source unit 2. This optical resonator 4 has a laser medium 11, a pair of reflecting members 12, a saturable absorber 14, and a wavelength band limiting element 15. In this embodiment, the excitation light input side is the "upstream side" and the oscillating laser output side is the "downstream side".

[0028] The laser medium 11 is, for example, an Nd:YAG crystal, which is disposed between a pair of reflecting members 12 constituting the optical resonator 4 and emits emission light excited by predetermined excitation light. More specifically, the laser medium 11 is excited by excitation light 22 having a wavelength near 808 [nm]. Then, the laser medium 11 emits light with a wavelength of approximately 1064 [nm] during the transition from the excited upper level to the lower level. In the following description, the light emitted by the laser medium 11 is referred to as emission light 21.

[0029] The mirror 12A and the output mirror 12B constitute a pair of reflecting members 12. The mirror 12A is, for example, a mirror that transmits excitation light 22 having a wavelength of approximately 808 [nm] emitted from the excitation light source unit 2 and reflects emission light 21 with a wavelength of approximately 1064 [nm] emitted from the laser medium 11 at a predetermined reflectance. The use of a mirror for the mirror 12A is merely an example and can be appropriately changed. For example, an element including a dielectric multilayer film may be used for the mirror 12A. Note that the above is only an example and the embodiments are not limited thereto.

[0030] The mirror 12B transmits a part of the light with a wavelength of approximately 1064 nm and reflects the rest. Note that the mirror 12A may be a dielectric multilayer film formed on the end face of the Nd:YAG crystal 11.

[0031] The saturable absorber 14 has an increased transmittance as it absorbs the emission light emitted from the laser medium. The saturable absorber 14 is constituted by, for example, a Cr 4+ :YAG crystal and is a member having the property that the light absorption rate decreases due to the saturation of light absorption, and functions as a passive Q-switch in the case of constituting a passive Q-switch pulsed laser device. That is, when the emission light 21 from the laser medium 11 is incident, the saturable absorber 14 absorbs the emission light 21, and with this absorption, the transmittance of the saturable absorber 14 increases. Then, when the electron density in the excited level increases and the excited level is filled, the saturable absorber 14 becomes transparent, increasing the Q value of the optical resonator and causing laser oscillation.

[0032] The wavelength band limiting element 15 is, for example, an etalon element, which is arranged on the downstream side of the saturable absorber 14 and limits the wavelength band of the emitted light 21. The wavelength band limiting element 15 has two reflecting planes orthogonal to the optical axis L of the optical resonator, that is, the optical axis L of the laser medium 11, and limits the wavelength band of the emitted light 21. For example, it transmits the emitted light 21 having a wavelength of about 1064 [nm]. Note that the etalon element may be uncoated. Alternatively, the etalon element may be coated with a partial reflection film. Further, the elements 11, 12, 14, and 15 constituting the optical resonator 4 may be joined.

[0033] Next, the operation of this laser device 1 will be described. As shown in FIG. 1, when the excitation light source unit 2 outputs excitation light 22 having a wavelength of about 808 nm, the excitation light 22 enters the laser medium 11 through the mirror 12A, excites the laser medium 11, and causes an inverted distribution. Next, when the emitted light 21 in the vicinity of the wavelength of 1064 nm is emitted due to the transition from the upper level to the lower level in the excited laser medium 11, the emitted light 21 enters and is absorbed by the saturable absorber 14. As the electron density of the excited level of the saturable absorber 14 increases and saturates with this absorption, the saturable absorber 14 becomes transparent, and as a result, the Q value of the optical resonator 4 increases and laser oscillation occurs. Then, the wavelength band limiting element 15 limits the band of the laser light to about 1064 nm, and the laser 23 is output from the mirror 12B.

[0034] Here, the resonance in the resonator 4 of the wavelength band limiting element 15 will be described with reference to FIGS. 2 to 4. FIG. 2 is a diagram schematically showing the resonance in the resonator 4 of the wavelength band limiting element 15. As will be described later, the saturable absorber 14 may be configured as the wavelength band limiting element 15. In this case, the element on the upstream side of the wavelength band limiting element 15 is the laser medium 11. Therefore, in FIG. 2, the element on the upstream side of the wavelength band limiting element 15 is shown as the laser medium 11 or the saturable absorber 14.

[0035] FIG. 2(a) is a diagram showing the relationship between the first distance R1 between the wavelength band limiting element 15 and the mirror 12B of the pair of reflecting members 12, and the second distance R2 between the output side of the laser medium 11 and the wavelength band limiting element 15. FIG. 2(b) is a diagram showing an example in which the wavelength band limiting element 15 and the mirror 12B are adjacent to each other. Here, adjacent means, for example, when the first distance R1 is within 50 microns. That is, adjacent means that the wavelength band limiting element 15 and the mirror 12B may or may not be in contact with each other.

[0036] FIGS. 2(c) and (d) show the wavelength of the laser 23 output from the mirror 12B. The horizontal axis represents the wavelength and the vertical axis represents the intensity.

[0037] As shown in FIG. 2(c), resonance occurs between the wavelength band limiting element 15 and the mirror 12B, and transmitted light with an intensity of 0.8 or more is randomly generated. In order to suppress such resonance, in a conventional general method, it is arranged obliquely with respect to the optical axis L so as not to cause another resonance with other mirrors in the resonator 4. For this reason, in order to arrange it obliquely with respect to the optical axis L, the structure becomes complicated and space is also required. As a result, it is difficult to use it in combination with other elements, which becomes a drawback for miniaturizing the resonator 4.

[0038] Therefore, in the present embodiment, as shown in FIG. 2(b), the wavelength band limiting element 15 and the mirror 12B are arranged adjacent to each other. In this case, as shown in FIG. 2(d), the resonance between the wavelength band limiting element 15 and the mirror 12B is further suppressed, so that the laser 23 having the target wavelength band-limited by the wavelength band limiting element 15 is output. In this way, as the distance R1 is made shorter, the resonance between the wavelength band limiting element 15 and the mirror 12B is suppressed. In particular, when the wavelength band limiting element 15 and the mirror 12B are arranged adjacent to each other, the resonance between the wavelength band limiting element 15 and the mirror 12B is further suppressed.

[0039] FIG. 3 is a diagram showing the spectrum of the laser 23 in the arrangement of FIG. 2(a). FIG. 3(a) is a diagram in which the horizontal axis represents the average excitation power and the vertical axis represents the average output. FIG. 3(b) is a diagram showing the spectrum of the laser 23 at the points indicated by the three round marks shown in FIG. 3(a). The horizontal axis represents the wavelength and the vertical axis represents the power. As shown in FIG. 3, the spectrum becomes multimode.

[0040] On the other hand, FIG. 4 is a diagram showing the spectrum of the laser 23 in the arrangement of FIG. 2(b). FIG. 4(a) is a diagram in which the horizontal axis represents the average excitation power and the vertical axis represents the average output. FIG. 4(b) is a diagram showing the spectrum of the laser 23 at the point indicated by the round mark in FIG. 4(a). The horizontal axis represents the wavelength and the vertical axis represents the power. As shown in FIG. 4, by suppressing resonance, the spectrum can be made single-mode.

[0041] As described above, the wavelength band limiting element 15 is arranged at a position where the generation of resonance between the mirror 12B of the reflecting member 12 is suppressed while maintaining the relationship that the two orthogonal reflecting planes are orthogonal to the optical axis L. Thereby, the generation of resonance is suppressed and the laser 23 of the target wavelength band can be output from the mirror 12B. In particular, by arranging the wavelength band limiting element 15 adjacent to the mirror 12B, the generation of resonance is further suppressed. Further, by arranging the wavelength band limiting element 15 while maintaining the relationship that the two reflecting planes are orthogonal to the optical axis L, it is possible to make the wavelength band limiting element 15 adjacent to or joined with the mirror 12B and the saturable absorber 14, and the optical resonator 4 can be made smaller.

[0042] (Modification of the First Embodiment) In the first embodiment, the case where the Nd:YAG crystal is used as the laser medium 11 and the Cr 4+ :YAG crystal is used as the saturable absorber 14 has been described. However, this is merely an example, and the combination of the laser medium 11 and the saturable absorber 14 may be changed as appropriate.

[0043] Therefore, in a modification of the first embodiment, in addition to the Nd:YAG crystal, the laser medium 11 may be, for example, Nd 3+ :YAG ceramics (emitting emission light 21 with a wavelength near 1064 [nm]), Nd:YVO4 (emitting emission light 21 with a wavelength near 1064 [nm]), Yb:YAG (emitting emission light 21 with a wavelength near 1030 [nm] or near 1050 [nm]). Also, when different laser media are used, excitation light having a wavelength optimal for excitation is appropriately selected.

[0044] When Nd:YAG, Nd:YVO4 or Yb:YAG is used as the laser medium 11, Cr:YAG or SESAM (Semiconductor Saturable Absorber Mirror), etc. is used as the saturable absorber 14.

[0045] Further, Er glass (emitting emission light 21 with a wavelength near 1540 [nm]) may be used as the laser medium 11. When Er glass is used as the laser medium 11, Co 2+ :MALO, Co 2+ :LaMgAl, U 2+ :CaF2 or Er 3+ :CaF2, etc. is used.

[0046] (Second Embodiment) The laser light source 1 according to the second embodiment is different from the laser light source 1 according to the first embodiment in that at least one of the mirrors 12A and 12B has a polarization function. The differences from the laser light source 1 according to the first embodiment will be described below.

[0047] FIG. 5 is a diagram showing the configuration of the optical resonator 4 according to the second embodiment. As shown in FIG. 5, the mirror 12C has a polarization function. The mirror 12A may be a polarization element, or both the mirror 12A and the mirror 12C may be polarization elements. In the optical resonator 4 according to the present embodiment, the case where the mirror 12C is a polarization element will be described as an example.

[0048] More specifically, the mirror 12C has a polarization element having a polarization selection function. The polarization element is an element whose reflectance with respect to the emitted light 21 varies depending on the polarization direction. Since the reflectances with respect to the emitted light in orthogonal polarization directions are different from each other, laser oscillation occurs with respect to the emitted light in the polarization direction with a higher reflectance. That is, as a result of the polarization direction of the emitted light being controlled by the polarization element, laser light with a stable polarization direction is generated.

[0049] The member used as the polarization element is not particularly limited. For example, as the polarization element according to the present embodiment, a photonic crystal polarization element using a photonic crystal, a wire grid polarization element using a wire grid, or a polarization element utilizing the orientation of a resin material may be used.

[0050] When the output of the laser light emitted from the laser device 1 is high, the electric field amplitude inside the optical resonator 4 becomes large. That is, since the load on the polarization element becomes high, it is more preferable to use a polarization element that can withstand the required output. In this regard, depending on the material or structure, etc., the photonic crystal can exhibit higher resistance to the load generated during laser oscillation. Also, while the wire grid has the property of absorbing the emitted light 21, the photonic crystal does not have such a property. Therefore, the photonic crystal polarization element is more likely to achieve higher oscillation efficiency than the wire grid polarization element. Based on the above, as an example, the case where a photonic crystal polarization element using a photonic crystal is used as the polarization element according to the present embodiment will be described. Note that, in order for laser oscillation with respect to the emitted light 21 in a desired polarization direction to be performed more efficiently, the difference in reflectance of the photonic crystal polarization element with respect to the emitted light 21 in mutually orthogonal polarization directions is preferably 1 [%] or more. However, it is not limited to this, and the difference in reflectance of the photonic crystal polarization element with respect to the emitted light 21 in mutually orthogonal polarization directions may be changed as appropriate.

[0051] Also, for more efficient laser oscillation and improved durability, the thickness per layer of the photonic crystal constituting the photonic crystal polarization element is preferably substantially the same as the wavelength of the emitted light 21. However, it is not limited thereto, and the thickness per layer of the photonic crystal may be appropriately changed. For example, the thickness per layer of the photonic crystal may be thinner (or thicker) by a predetermined value than the wavelength of the emitted light 21. Further, as the material of the photonic crystal, for example, SiO2, SiN, Ta2O5, etc. can be used. However, it is not limited thereto, and the material of the photonic crystal may be appropriately changed.

[0052] As described above, in the laser device 1 according to the present embodiment, one of the pair of reflecting members 12 is a polarization element. Thereby, since the length of the optical resonator becomes shorter compared to the case where the polarization element is inserted between the pair of reflecting members 12, the laser device 1 according to the present embodiment can not only generate a pulsed laser with a stable polarization direction, but also suppress an increase in pulse width and a decrease in peak intensity due to an increase in the length of the optical resonator, and can miniaturize the optical resonator 4 and the laser device 1.

[0053] (Modification of the Second Embodiment) FIG. 6 is a diagram showing a configuration example of the optical resonator 4 according to a modification of the second embodiment. As shown in FIG. 6, a spacer layer s1 may be formed in the optical resonator 4. For example, the spacer layer s1 is composed of an air layer or a dielectric layer. The spacer layer s1 can be used for adjusting the pulse width and peak intensity of the laser light 23. Further, the spacer layer s1 may be formed between the laser medium 11 and the saturable absorber 14.

[0054] (Third Embodiment) The laser light source 1 according to the second embodiment is different from the laser light source 1 according to the second embodiment in that a saturable absorber is formed in two reflection planes of the wavelength band limiting element. The differences from the laser light source 1 according to the second embodiment will be described below.

[0055] FIG. 7 is a diagram showing the configuration of the optical resonator 4 according to the third embodiment. As shown in FIG. 7, the wavelength band limiting element 16 has a saturable absorber within two reflective planes of the wavelength band limiting element. More specifically, the wavelength band limiting element 16 has a saturable absorber whose transmittance increases with the absorption of the emitted light emitted from the laser medium, and two parallel reflective plane portions formed on both sides of the saturable absorber.

[0056] As described above, in the laser device 1 according to the present embodiment, a saturable absorber is formed within two reflective planes of the wavelength band limiting element 16. As a result, the length of the optical resonator can be made shorter compared to the case where the saturable absorber 14 and the wavelength band limiting element 15 are formed separately. Therefore, the laser device 1 according to the present embodiment can further suppress the increase in the pulse width and the decrease in the peak intensity caused by the increase in the length of the optical resonator, and the optical resonator 4 and the laser device 1 can be further miniaturized.

[0057] (First Modification of the Third Embodiment) FIG. 8 is a diagram showing a configuration example of the optical resonator 4 according to the first modification of the third embodiment. As shown in FIG. 8, a spacer layer s2 may be formed within the optical resonator 4. For example, the spacer layer s2 is formed of an air layer or a dielectric layer. The spacer layer s2 can be used for adjusting the pulse width and peak intensity of the laser light 23.

[0058] (Second Modification of the Third Embodiment) FIG. 9 is a diagram showing an example in which a heat dissipation substrate e1 is formed within the optical resonator 4 according to the second modification of the third embodiment. As shown in FIG. 9, a heat dissipation substrate e1 may be further formed within the optical resonator 4. For example, the heat dissipation substrate e1 is formed of sapphire. The heat dissipation substrate can suppress the temperature rise within the optical resonator 4. Also, although the heat dissipation substrate e1 is formed within the optical resonator 4 according to the third embodiment, it is not limited thereto. For example, a heat dissipation substrate e1 may be formed within all the optical resonators 4 disclosed in the present embodiment (for example, the optical resonators 4 shown in FIGS. 1, 5, 6, 7, 8, etc. described above, and the optical resonators 4 shown in FIGS. 10, 11, 12, 13, 14, 15, etc. described later).

[0059] (Embodiment 4) The laser light source 1 according to the fourth embodiment is different from the laser light source 1 according to the first embodiment in that the saturable absorber is composed of a saturable absorber having a specific crystal orientation. The differences from the laser light source 1 according to the first embodiment will be described below.

[0060] FIG. 10 is a diagram showing the configuration of the optical resonator 4 according to the fourth embodiment. As shown in FIG. 10, the saturable absorber 17 has a saturable absorber having a specific crystal orientation. This saturable absorber 17 is, for example, Cr4 + :YAG crystal. The Cr4 + :YAG crystal has anisotropy, and depending on the crystal orientation, it has a difference in transmittance for the emitted light in polarization directions orthogonal to each other. As a result, it is possible to output laser light with a stable polarization direction. In particular, when used in the <110> orientation, the difference in transmittance for the emitted light in polarization directions orthogonal to each other tends to be maximized, and the polarization direction of the laser light output from the passive Q-switch laser device can be further stabilized.

[0061] As described above, the laser device 1 according to the present embodiment is configured with a saturable absorber 17 having a specific crystal orientation. Thereby, the length of the optical resonator 4 can be made shorter compared to the case where the polarization element is inserted between the pair of reflecting members 12. As a result, the laser device 1 according to the present embodiment can not only generate a pulsed laser with a stable polarization direction, but also suppress an increase in the pulse width and a decrease in the peak intensity caused by an increase in the length of the optical resonator 4, and the optical resonator 4 and the laser device 1 can be miniaturized.

[0062] (Modification of Embodiment 4) FIG. 11 is a diagram showing a configuration example of the optical resonator 4 according to a modification of the fourth embodiment. As shown in FIG. 11, a spacer layer s3 may be formed in the optical resonator 4. For example, the spacer layer s3 is formed of an air layer or a dielectric layer. The spacer layer s3 can be used for adjusting the pulse width and peak intensity of the laser light 23. Further, the spacer layer may be formed between the laser medium 11 and the saturable absorber 17.

[0063] (Fifth Embodiment) The laser light source 1 according to the fifth embodiment is different from the laser light source 1 according to the fourth embodiment in that a saturable absorber having a specific crystal orientation is formed in two reflection planes of the wavelength band limiting element. Hereinafter, the differences from the laser light source 1 according to the fourth embodiment will be described.

[0064] FIG. 12 is a diagram showing the configuration of the optical resonator 4 according to the fourth embodiment. As shown in FIG. 12, the wavelength band limiting element 18 has a saturable absorber having a specific crystal orientation in two reflection planes of the wavelength band limiting element. More specifically, the wavelength band limiting element 18 includes a saturable absorber having a specific crystal orientation in which the transmittance increases as the emitted light emitted from the laser medium is absorbed, and two parallel reflection plane portions formed on both side surfaces of the saturable absorber.

[0065] As described above, the laser device 1 according to the present embodiment forms a saturable absorber having a specific crystal orientation in two reflection planes of the wavelength band limiting element 18. Thereby, the laser device 1 according to the present embodiment can not only generate a pulse laser with a stable polarization direction, but also can make the length of the optical resonator shorter than the case where the saturable absorber 14 and the wavelength band limiting element 15 are respectively configured. Therefore, the laser device 1 according to the present embodiment can further suppress an increase in the pulse width and a decrease in the peak intensity caused by an increase in the length of the optical resonator, and can further reduce the size of the optical resonator 4 and the laser device 1.

[0066] (Modification of the Fifth Embodiment) FIG. 13 is a diagram showing a configuration example of the optical resonator 4 according to a modified example of the fifth embodiment. As shown in FIG. 13, a spacer layer s4 may be formed in the optical resonator 4. For example, the spacer layer s4 is formed of an air layer or a dielectric layer. The spacer layer s4 can be used for adjusting the pulse width and peak intensity of the laser beam 23 and the like.

[0067] (Sixth Embodiment) The laser light source 1 according to the sixth embodiment is different from the laser light source 1 according to the second embodiment in that a mirror having a polarization function and a wavelength band limiting element 15 are integrally formed. Hereinafter, the differences from the laser light source 1 according to the first embodiment will be described.

[0068] FIG. 14 is a diagram showing the configuration of the optical resonator 4 according to the sixth embodiment. As shown in FIG. 14, the output mirror 12D has an etalon function and a polarization function. That is, the downstream plane of the two reflecting planes orthogonal to the optical axis constitutes the downstream reflecting member of the pair of reflecting members 12. Further, the output mirror 12D has a polarization element having a polarization selection function. The polarization element is an element in which the transmittance and reflectance of the emitted light 21 differ depending on the polarization direction. Since the reflectances for the emitted lights in the orthogonal polarization directions are different, laser oscillation occurs for the emitted light in the polarization direction with the higher reflectance. That is, as a result of the polarization direction of the emitted light being controlled by the polarization element, laser light with a stable polarization direction is generated.

[0069] As described above, in the laser device 1 according to the present embodiment, the output mirror 12D is integrally formed as a mirror having a polarization function and an element having an etalon function. Thereby, the laser device 1 according to the present embodiment can not only generate a pulsed laser with a stable polarization direction, but also can make the length of the optical resonator shorter than in the case where the mirror 12C and the wavelength band limiting element 15 are respectively configured. For this reason, the laser device 1 according to the present embodiment can further suppress an increase in pulse width and a decrease in peak intensity caused by an increase in the length of the optical resonator, and can further reduce the size of the optical resonator 4 and the laser device 1.

[0070] (Modification of the Sixth Embodiment) FIG. 15 is a diagram showing a configuration example of the optical resonator 4 according to a modification of the sixth embodiment. As shown in FIG. 15, a spacer layer s5 may be formed in the optical resonator 4. For example, the spacer layer s4 is formed of an air layer or a dielectric layer. The spacer layer s5 can be used for adjusting the pulse width and peak intensity of the laser light 23 and the like.

[0071] Note that the laser device 1 according to the present embodiment can be applied to various devices, systems, and the like. For example, the laser device 1 according to the present embodiment is a device used for processing metals, semiconductors, dielectrics, resins, or living bodies, a distance measuring device used for distance measurement (for example, LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging)), a device used for LIBS (Laser Induced Breakdown Spectroscopy), a device used for refractive eye surgery (for example, LASIK, etc.), or a device used for depth sensing or a LiDAR for atmospheric observation such as aerosol. Note that the devices to which the laser device 1 according to the present embodiment is applied are not limited to the above.

[0072] Note that the present technology can adopt the following configuration.

[0073] (1) A laser medium disposed between a pair of reflecting members and emitting emission light excited by predetermined excitation light; A wavelength band limiting element disposed on the emission light emission side between the pair of reflecting members, having two reflecting planes orthogonal to the optical axis of the laser medium, and limiting the wavelength band of the emission light; Comprising: The wavelength band limiting element is disposed at a position where resonance generation with the reflecting member on the emission side of the laser light is suppressed while maintaining the relationship with the optical axis, and is an optical resonator.

[0074] (2) The optical resonator according to (1), wherein the wavelength band limiting element and the reflecting member on the emission side of the laser light are adjacent to each other.

[0075] (3) The distance between the wavelength band limiting element and the reflecting member on the emission side of the laser light is within 50 microns, and the optical resonator according to (1) or (2).

[0076] (4) The optical resonator according to any one of (1) to (3), further comprising a saturable absorber disposed between the laser medium and the wavelength band limiting element, the transmittance of which increases with the absorption of the emitted light emitted from the laser medium.

[0077] (5) The optical resonator according to any one of (1) to (3), wherein the two reflecting planes are saturable absorbers whose transmittance increases with the absorption of the emitted light emitted from the laser medium.

[0078] (6) The optical resonator according to (5), wherein a space layer is provided between the laser medium and the wavelength band limiting element.

[0079] (7) The optical resonator according to (4), wherein a space layer is provided between the saturable absorber and the wavelength band limiting element.

[0080] (8) The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and is arranged in the optical resonator so as to have different transmittances for the emitted light in two polarization directions orthogonal to each other emitted from the laser medium. The optical resonator according to any one of (4) to (7).

[0081] (9) The optical resonator according to (8), wherein a space layer is provided between the saturable absorber and the wavelength band limiting element.

[0082] (10) The two reflecting planes are saturable absorbers whose transmittance increases with the absorption of the emitted light emitted from the laser medium. The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and is arranged in the optical resonator so as to have different transmittances for the emitted light in two polarization directions orthogonal to each other emitted from the laser medium. The optical resonator according to (1).

[0083] (11) The two reflecting planes are saturable absorbers whose transmittance increases with the absorption of the emitted light emitted from the laser medium. The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and is arranged in the optical resonator so as to have different transmittances for the emitted light in two polarization directions orthogonal to each other emitted from the laser medium. A space layer is provided between the laser medium and the wavelength band limiting element. The optical resonator according to (1).

[0084] (12) At least one of the pair of reflecting members is a polarization element, and the polarization element has different reflectivities for the emitted light in polarization directions orthogonal to each other. The optical resonator according to any one of (1) to (11).

[0085] (13) The plane on the emission side of the laser light of the two reflecting planes orthogonal to the optical axis constitutes the reflecting member on the emission side of the pair of reflecting members. The optical resonator according to any one of (1) to (12).

[0086] (14) The optical resonator according to any one of (1) to (13) further includes a heat dissipation substrate disposed on the side opposite to the emission side of the laser light of the laser medium.

[0087] (15) The polarization element is a photonic crystal composed of a periodic structure of an inorganic material. The optical resonator according to (12).

[0088] (16) The optical resonator according to any one of (1) to (15), An excitation light source unit that emits the excitation light to the laser medium, A laser device comprising

[0089] (17) A saturable absorber whose transmittance increases with the absorption of the emitted light emitted from the laser medium, and two parallel reflecting plane portions formed on both sides of the saturable absorber Components of an optical resonator comprising

[0090] (18) A pair of reflecting members constituting the optical resonator Disposed on the side where the emitted light is emitted between the pair of reflecting members, having two reflecting planes orthogonal to the optical axis of the optical resonator, and a wavelength band limiting element for limiting the wavelength band of the emitted light The planes on the side where the emitted light is emitted of the two reflecting planes orthogonal to the optical axis constitute the reflecting member on the side where the emitted light is emitted of the pair of reflecting members, which are components of the optical resonator

[0091] Aspects of the present disclosure are not limited to the individual embodiments described above, but also include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-described content. That is, various additions, changes, and partial deletions are possible without departing from the conceptual ideas and spirit of the present disclosure derived from the content defined in the claims and their equivalents

Description of Reference Numerals

[0092] 1: Laser device, 2: Excitation light source unit, 4: Optical resonator, 11: Laser medium, 12: Pair of reflecting members, 12A: Mirror, 12B, 12C, 12D: Output mirror, 14: Saturable absorber, 15, 16: Wavelength band limiting element, 17: Saturable absorber, 18: Wavelength band limiting element, s1 to s5: Spacer layer, e1: Heat dissipation substrate

Claims

1. A laser medium disposed between a pair of reflecting members and emitting emission light excited by predetermined excitation light; A wavelength band limiting element disposed between the pair of reflecting members, disposed on the side where the emission light between the pair of reflecting members is emitted, having two reflecting planes orthogonal to the optical axis of the laser medium, limiting the wavelength band of the emission light, and being conductive in the wavelength band of the emission light; Comprising: The wavelength band limiting element is in contact with the incident side surface of the reflecting member on the emission side of the emission light, and is disposed at a position that suppresses the generation of resonance components outside the wavelength band of the emission light between the reflecting member on the emission side of the laser light and the wavelength band limiting element. An optical resonator.

2. The optical resonator according to claim 1, further comprising a saturable absorber disposed between the laser medium and the wavelength band limiting element, the transmittance of which increases with the absorption of the emission light emitted from the laser medium.

3. The optical resonator according to claim 2, wherein a space layer is provided between the saturable absorber and the laser medium or the wavelength band limiting element.

4. The optical resonator according to claim 1, wherein within the two reflecting planes is a saturable absorber whose transmittance increases with the absorption of the emission light emitted from the laser medium.

5. The optical resonator according to claim 4, wherein a space layer is provided between the laser medium and the wavelength band limiting element.

6. The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and is disposed in the optical resonator so as to have different transmittances for emission light in two polarization directions orthogonal to each other emitted from the laser medium. The optical resonator according to claim 2.

7. The optical resonator according to claim 6, wherein a space layer is provided between the saturable absorber and the laser medium or the wavelength band limiting element.

8. Within the two reflecting planes is a saturable absorber whose transmittance increases with the absorption of the emission light emitted from the laser medium. The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and is disposed in the optical resonator so as to have different transmittances for emission light in two polarization directions orthogonal to each other emitted from the laser medium. The optical resonator according to claim 1.

9. The two reflective planes are saturable absorbers whose transmittance increases with the absorption of the emitted light emitted from the laser medium. The saturable absorber is a crystal having first to third crystal axes orthogonal to each other, and is arranged in the optical resonator so as to have different transmittances for the emitted light in two polarization directions orthogonal to each other emitted from the laser medium. A space layer is provided between the laser medium and the wavelength band limiting element. The optical resonator according to claim 1.

10. At least one of the pair of reflective members is a polarization element, and the polarization element has different reflectivities for the emitted light in polarization directions orthogonal to each other. The optical resonator according to claim 1.

11. The plane on the emission side of the laser light of the two reflective planes orthogonal to the optical axis is integrally formed with the reflective member on the emission side of the pair of reflective members. The optical resonator according to claim 1.

12. The polarization element is a photonic crystal composed of a periodic structure of an inorganic material. The optical resonator according to claim 10.

13. The optical resonator according to claim 1, further comprising a heat dissipation substrate disposed on the side opposite to the emission side of the laser light of the laser medium.

14. The optical resonator according to claim 1, An excitation light source unit that emits the excitation light to the laser medium, A laser device comprising.

15. A laser medium disposed between a pair of reflective members and emitting emitted light excited by predetermined excitation light, A wavelength band limiting element that is disposed between the pair of reflective members, is disposed on the side where the emitted light between the pair of reflective members is emitted, has two reflective planes orthogonal to the optical axis of the laser medium, and limits the wavelength band of the emitted light. Comprising, The wavelength band limiting element is A saturable absorber whose transmittance increases with the absorption of the emitted light emitted from the laser medium, And two parallel reflective plane portions formed on both side surfaces of the saturable absorber. The wavelength band limiting element is in contact with the incident side surface of the reflective member on the emission side of the laser light. The optical resonator.

16. A laser medium disposed between a pair of reflective members and emitting emitted light excited by predetermined excitation light, A wavelength band limiting element that is disposed between the pair of reflective members, is disposed on the side where the emitted light between the pair of reflective members is emitted, has two reflective planes orthogonal to the optical axis of the laser medium, and limits the wavelength band of the emitted light. Comprising, The plane on the side from which the emitted light is emitted of the two reflecting planes orthogonal to the optical axis constitutes a reflecting member on the side from which the emitted light is emitted of the pair of reflecting members, which is an optical resonator.

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