WO2022249360A1 - レーザ素子及び電子機器 - Google Patents
レーザ素子及び電子機器 Download PDFInfo
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- WO2022249360A1 WO2022249360A1 PCT/JP2021/020077 JP2021020077W WO2022249360A1 WO 2022249360 A1 WO2022249360 A1 WO 2022249360A1 JP 2021020077 W JP2021020077 W JP 2021020077W WO 2022249360 A1 WO2022249360 A1 WO 2022249360A1
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- H01S5/00—Semiconductor lasers
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- H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
- H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
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Definitions
- the present disclosure relates to laser elements and electronic devices.
- the peak power of a laser is defined as pulse energy ⁇ pulse width, and it is important to obtain a shorter pulse width in order to obtain higher peak power.
- a Q-switched solid-state laser that outputs laser pulses is characterized in that the length of its own cavity is proportional to the pulse width obtained, and the minimum cavity length is determined by the length of the solid-state laser medium used.
- the length of the solid-state laser medium installed in the cavity as the gain medium is determined by the amount of absorption of the pumping light. However, the excitation efficiency is remarkably lowered without
- the length of the solid-state laser medium is not preferable to make the length of the solid-state laser medium shorter than the excitation light absorption length, and it is not possible to obtain a shorter pulse.
- the length of the solid-state laser medium is shortened in an attempt to obtain a short pulse width, the amount of pumping light absorbed is reduced and the pumping efficiency is lowered.
- the thickness of the solid-state laser medium that can be used is limited by the absorption length determined by the wavelength of the excitation semiconductor laser and the absorption coefficient of the solid-state laser medium at that wavelength.
- the absorption length for excitation light with a wavelength of 808 nm is about 10 mm.
- the remaining excitation light that has not been absorbed returns to the semiconductor laser side to destabilize the operation or cause heat generation.
- a method of folding excitation light many times has been proposed, but it requires a complicated excitation optical system and has problems of miniaturization and low cost.
- Patent Document 3 a method of integrally laminating a surface-emitting laser (VCSEL) for excitation and a solid-state laser medium has been proposed.
- VCSEL surface-emitting laser
- thermal interference may occur between the surface-emitting laser and the solid-state laser medium.
- the laser light oscillation efficiency of the surface-emitting laser is lowered, and the light wavelength conversion efficiency of the solid-state laser medium is lowered.
- the present disclosure provides a laser element and an electronic device that can prevent a decrease in laser light oscillation efficiency and a decrease in light wavelength conversion efficiency due to thermal interference.
- a laminated semiconductor layer having a first reflective layer for a first wavelength and an active layer that performs surface emission of the first wavelength, A second reflective layer for a second wavelength on a first surface facing the laminated semiconductor layer disposed on the rear side of the optical axis of the laminated semiconductor layer, and a second reflective layer for the first wavelength on a second surface opposite to the first surface.
- a laser medium having a third reflective layer for a fourth reflective layer for the second wavelength, disposed on the second surface or disposed on the rear side of the optical axis from the second surface; a first resonator that resonates the light of the first wavelength between the first reflective layer and the third reflective layer; a second resonator that resonates the light of the second wavelength between the second reflective layer and the fourth reflective layer; a heat exhaust unit disposed between the laminated semiconductor layer and the laser medium for exhausting heat generated by at least one of the laminated semiconductor layer and the laser medium;
- a laser element is provided in which the optical axis of the laminated semiconductor layer and the optical axis of the laser medium are arranged on one axis.
- the heat exhaust part may have a first member disposed between the laminated semiconductor layer and the laser medium and having a higher thermal conductivity than the laser medium.
- a metal layer having higher thermal conductivity than the laminated semiconductor layer and the laser medium may be provided on part or all of the surface of the first member facing the laser medium.
- a second member may be provided that is bonded to the side surface of the laminated semiconductor layer, the side surface of the first member, and the side surface of the laser medium, and radiates heat transferred to the first member.
- the second member may be arranged to cover side surfaces of the laminated semiconductor layer and the laser medium, and the bonding wire.
- the first member includes at least one of sapphire and diamond
- the second member may contain a metal material.
- a protective layer may be provided on the surface of the first member on the side facing the laminated semiconductor layer to transmit the light of the first wavelength and reflect the light of the second wavelength.
- the first member may have a first region that transmits the light of the first wavelength, and a second region that is arranged around the first region and has a higher thermal conductivity than the laser medium.
- the second region may be an insulating material or a metal material.
- the second region is arranged to surround the first region,
- the outer peripheral surface of the second region or the corners of the outer peripheral surface may be positioned equidistant from the center position of the first region.
- a plurality of the first resonators and a plurality of the second resonators may be provided in the planar direction of the laminated semiconductor layer, the heat exhaust part, and the laser medium.
- the heat exhaust part may have an air gap arranged between the laminated semiconductor layer and the laser medium.
- a first optical element may be provided between the second reflective layer and the fourth reflective layer to enlarge the beam diameter of the light of the second wavelength.
- the first resonator may have a second optical element for condensing the light of the first wavelength in the optical axis direction.
- a saturable absorber having the fourth reflective layer on a third surface opposite to the laser medium;
- An optical axis of the laminated semiconductor layer, an optical axis of the laser medium, and an optical axis of the saturable absorber may be arranged on one axis.
- the laminated semiconductor layer, the laser medium, and the saturable absorber may be integrally bonded.
- a polarization control element may be provided between the laser medium and the saturable absorber or on the rear side of the optical axis relative to the saturable absorber, and controls the polarization state of the light of the second wavelength.
- the fourth reflective layer may be an out-coupling mirror in the second resonator.
- the laminated semiconductor layer is arranged closer to the laser medium than the first reflective layer and has a fifth reflective layer for the first wavelength,
- the fifth reflective layer may transmit part of the light of the first wavelength.
- a laser element and a control unit that controls emission of light from the laser element
- the laser element is a laminated semiconductor layer having a first reflective layer for a first wavelength and an active layer for surface emission of the first wavelength; A second reflective layer for a second wavelength on a first surface facing the laminated semiconductor layer disposed on the rear side of the optical axis of the laminated semiconductor layer, and a second reflective layer for the first wavelength on a second surface opposite to the first surface.
- a laser medium having a third reflective layer for a fourth reflective layer for the second wavelength, disposed on the second surface or disposed on the rear side of the optical axis from the second surface; a first resonator that resonates the light of the first wavelength between the first reflective layer and the third reflective layer; a second resonator that resonates the light of the second wavelength between the second reflective layer and the fourth reflective layer; a heat exhaust unit disposed between the laminated semiconductor layer and the laser medium for exhausting heat generated by at least one of the laminated semiconductor layer and the laser medium;
- An electronic device is provided in which the optical axis of the laminated semiconductor layer and the optical axis of the laser medium are arranged on one axis.
- FIG. 1 is a diagram showing the basic configuration of a laser device according to the present disclosure
- FIG. FIG. 2 is a schematic cross-sectional view of a laser device provided with a heat exhaust portion according to the first embodiment
- FIG. 5 is a schematic cross-sectional view of a laser device having a heat exhausting section according to a second embodiment
- FIG. 11 is a schematic cross-sectional view of a laser device having a heat exhausting section according to a third embodiment
- FIG. 11 is a schematic cross-sectional view of a laser device having a heat exhausting part according to a fourth embodiment
- FIG. 11 is a schematic cross-sectional view of a laser device provided with a heat exhaust part according to a fifth embodiment
- FIG. 11 is a schematic cross-sectional view of a laser device provided with a heat exhaust part according to a sixth embodiment
- FIG. 11 is a schematic cross-sectional view of a laser device provided with a heat exhaust part according to a seventh embodiment
- FIG. 11 is a schematic cross-sectional view of a laser device having a heat exhausting section according to an eighth embodiment
- FIG. 11 is a schematic cross-sectional view of a laser device provided with a heat exhausting section according to a ninth embodiment
- FIG. 2 is a schematic cross-sectional view of a laser array in which a plurality of lens elements are arranged one-dimensionally or two-dimensionally;
- FIG. 4 is a diagram showing the temperature distribution of laser light sources in the center of a laser array that does not have a heat exhausting section;
- FIG. 4 is a diagram showing the temperature distribution of the laser light source in the central part of the laser array provided with the heat exhaust part;
- FIG. 4 is a diagram showing the temperature distribution of laser light sources at corners of a laser array that does not have a heat exhausting section;
- FIG. 4 is a diagram showing the temperature distribution of the laser light sources at the corners of the laser array provided with the heat exhausting section;
- FIG. 4 is a diagram schematically showing the manufacturing process of the laser device of the present disclosure;
- FIG. 4 is a diagram showing a laser device in which a first transparent medium is arranged between an excitation light source and a solid-state laser medium;
- FIG. 2 is a diagram showing the basic configuration of a laser device without a saturable absorber;
- the top view seen from the Z direction of FIG. 17A. 1 is a cross-sectional view of a laser amplifying device according to the present disclosure;
- FIG. 1 is a cross-sectional view of a laser amplifying device according to the present disclosure;
- FIG. 1 is a perspective view of a laser amplification element according to the present disclosure
- FIG. FIG. 2 is a plan view schematically showing an optical path of laser light within the laser amplification element
- FIG. 18B is a cross-sectional view of a laser amplification element in which the heat exhaust performance of the first heat exhaust member of FIG. 18A is improved
- FIG. 19B is a cross-sectional view taken along line AA of FIG. 19A;
- FIG. 21 is a block diagram showing an example of the functional configuration of the camera and CCU shown in FIG. 20; The figure which shows an example of a schematic structure of a microsurgery system.
- the laser device may have components and functions that are not illustrated or described. The following description does not exclude components or features not shown or described.
- a laser device has a structure in which a structure using a part of a surface-emitting laser as an excitation light source and a solid-state laser medium for Q-switching are integrally joined.
- laser elements according to the present disclosure may include laser elements that do not have a Q-switch function, but first, a laser element that has a Q-switch function will be described.
- two resonators share the Q-switching solid-state laser medium. These two resonators have a first resonator resonating at a first wavelength and a second resonator (also called Q-switched solid-state laser resonator) resonating at a second wavelength.
- the laser element according to the present disclosure is an integrated laminated structure that can be manufactured using semiconductor process technology, it is excellent in mass productivity and in laser output stability.
- the excitation light source is a form of vertical cavity surface emitting laser (VCSEL).
- VCSEL vertical cavity surface emitting laser
- a laser device according to the present disclosure has a structure in which a solid-state laser medium is arranged between a laminated semiconductor layer and a mirror arranged outside the laminated semiconductor layer, as will be described later.
- the laser device can generate a laser pulse with a short pulse width by Q-switching, but the heat generated by the non-conversion of the excitation light source is transferred to the solid-state laser medium, and the temperature of the solid-state laser medium rises. There is a risk.
- the temperature of the solid-state laser medium rises, the conversion efficiency of the light wavelength from the first wavelength to the second wavelength in the solid-state laser medium decreases.
- the higher the optical output intensity of the pumping light source the greater the effect of lowering the conversion efficiency of the light wavelength in the solid-state laser medium.
- the heat generated in the solid-state laser medium may be transferred to the excitation light source, further increasing the temperature of the excitation light source.
- the IL characteristic (luminous efficiency) of the excitation light source deteriorates.
- the temperature of the active layer (junction temperature Tj) of the excitation light source rises, degrading long-term reliability (MTTF: Mean Time To Failure).
- the laser device has the following three features.
- the first resonator and the second resonator share a solid-state laser medium.
- the first cavity includes an excitation light source and a solid-state laser medium.
- the second resonator includes a solid-state laser medium and a saturable absorber, and performs Q-switched laser oscillation with excitation light from the first resonator.
- a heat exhaust part is provided between the excitation light source and the solid-state laser medium.
- the heat exhaust part exhausts heat generated by at least one of the excitation light source and the solid-state laser medium.
- the excitation light source, solid-state laser medium, and saturable absorber have an integrated structure.
- excitation light generated by injecting current into the excitation light source is absorbed by the solid-state laser medium within the first cavity.
- the solid-state laser medium constitutes a second cavity together with a saturable absorber placed adjacent to the first cavity.
- the solid-state laser medium becomes sufficiently excited, the output of spontaneous emission light increases, and when it exceeds a certain threshold, the light absorption rate in the saturable absorber drops sharply, and the spontaneous emission light generated in the solid-state laser medium is It becomes permeable through the saturable absorber and causes stimulated emission in the solid-state laser medium. This causes Q-switched pulsing.
- FIG. 1 is a diagram showing the basic configuration of a laser device 1 according to the present disclosure.
- a laser element 1 in FIG. 1 has a configuration in which an excitation light source 2, a solid-state laser medium 3, and a saturable absorber 4 are joined together.
- the excitation light source 2 is a partial structure of the VCSEL described above, and has laminated semiconductor layers of a laminated structure. Below, the excitation light source 2 may also be referred to as the laminated semiconductor layer 2 .
- the excitation light source 2 in FIG. 1 is formed by laminating the substrate 5, the n-contact layer 33, the fifth reflective layer R5, the clad layer 6, the active layer 7, the clad layer 8, the pre-oxidation layer 31, and the first reflective layer R1 in this order. It has structure.
- the laser device 1 in FIG. 1 has a bottom emission type configuration in which continuous wave (CW) excitation light is emitted from the substrate 5, the CW excitation light is emitted from the first reflective layer R1 side.
- a top emission type configuration is also possible.
- the substrate 5 is an n-GaAs substrate 5, for example. Since the n-GaAs substrate 5 absorbs light of the first wavelength ⁇ 1, which is the excitation wavelength of the excitation light source 2, at a constant rate, it is desirable to make it as thin as possible. On the other hand, it is desirable to have a thickness sufficient to maintain the mechanical strength during the joining process, which will be described later.
- the active layer 7 performs surface emission of the first wavelength ⁇ 1.
- the clad layers 6 and 8 are, for example, AlGaAs clad layers.
- the first reflective layer R1 reflects light of the first wavelength ⁇ 1.
- the fifth reflective layer R5 has a constant transmittance for light of the first wavelength ⁇ 1.
- an electrically conductive semiconductor distributed reflective layer DBR: Distributed Bragg Reflector
- a current is injected from the outside through the first reflective layer R1 and the fifth reflective layer R5, recombination and light emission occur in the quantum well in the active layer 7, and laser oscillation of the first wavelength ⁇ 1 is performed.
- a part of the pre-oxidation layer (for example, AlAs layer) 31 on the clad layer side of the first reflective layer R1 is oxidized to become a post-oxidation layer (for example, Al 2 O 3 layer) 32 .
- the fifth reflective layer R5 is arranged on the n-GaAs substrate 5, for example.
- the fifth reflective layer R5 has a multilayer reflective film made of Al z1 Ga 1-z1 As/Al z2 Ga 1-z2 As (0 ⁇ z1 ⁇ z2 ⁇ 1) doped with an n-type dopant (eg, silicon).
- the fifth reflective layer R5 is also called n-DBR. More specifically, an n-contact layer 33 is arranged between the fifth reflective layer R5 and the n-GaAs substrate 5. As shown in FIG.
- the active layer 7 has, for example, a multiple quantum well layer in which an Al x1 In y1 Ga 1-x1-y1 As layer and an Al x3 In y3 Ga 1-x3-y3 As layer are laminated.
- the first reflective layer R1 has, for example, a multiple reflection film made of Alz3Ga1-z3As/Alz4Ga1-z4As (0 ⁇ z3 ⁇ z4 ⁇ 1) doped with a p-type dopant (eg, carbon).
- the first reflective layer R1 is also called p-DBR.
- Each of the semiconductor layers R5, 6, 7, 8, R1 in the excitation light source 2 can be formed using a crystal growth method such as MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy). After crystal growth, processes such as mesa etching for element isolation, formation of an insulating film, and vapor deposition of an electrode film enable driving by current injection.
- MOCVD metal organic chemical vapor deposition
- MBE molecular beam epitaxy
- a solid-state laser medium 3 is bonded to the end surface of the n-GaAs substrate 5 of the excitation light source 2 opposite to the fifth reflective layer R5.
- the end surface of the solid-state laser medium 3 on the pumping light source 2 side is referred to as a first surface F1
- the end surface of the solid-state laser medium 3 on the saturable absorber 4 side is referred to as a second surface F2.
- the laser pulse emitting surface of the saturable absorber 4 is called a third surface F3
- the end surface of the excitation light source 2 on the solid-state laser medium 3 side is called a fourth surface F4.
- An end face of the saturable absorber 4 on the solid-state laser medium 3 side is called a fifth face F5.
- the fourth surface F4 of the excitation light source 2 is joined to the first surface F1 of the solid-state laser medium 3, and the second surface F2 of the solid-state laser medium 3 is connected to the saturable absorber 4. is joined to the fifth surface F5 of the .
- the laser device 1 in FIG. 1 includes a first resonator 11 and a second resonator 12.
- the first resonator 11 resonates light with a first wavelength ⁇ 1 between the first reflective layer R1 in the excitation light source 2 and the third reflective layer R3 in the solid-state laser medium 3 .
- the second resonator 12 resonates light of the second wavelength ⁇ 2 between the second reflective layer R2 in the solid-state laser medium 3 and the fourth reflective layer R4 in the saturable absorber 4 .
- the second resonator 12 is also called a Q-switched solid-state laser resonator 12.
- a third reflective layer R3, which is a highly reflective layer, is provided in the solid-state laser medium 3 so that the first resonator 11 can perform stable resonant operation.
- a normal excitation light source 2 has a partially reflecting mirror for emitting the light of the first wavelength ⁇ 1 to the outside at the position of the third reflecting layer R3 in FIG.
- the third reflective layer R3 is used to confine the power of the pumping light of the first wavelength ⁇ 1 within the first resonator 11. It has a reflective layer.
- first reflective layer R1, fifth reflective layer R5, and third reflective layer R3 are provided inside the first resonator 11 composed of the excitation light source 2 and the solid-state laser medium 3. be done. Therefore, the first resonator 11 has a coupled cavity structure.
- the solid-state laser medium 3 is excited. This causes Q-switched laser pulse oscillation in the second resonator 12 .
- the second resonator 12 resonates light of the second wavelength ⁇ 2 between the second reflective layer R2 in the solid-state laser medium 3 and the fourth reflective layer R4 in the saturable absorber 4 .
- the second reflective layer R2 is a highly reflective layer, while the fourth reflective layer R4 is a partially reflective layer. In FIG. 1, the fourth reflective layer R4 is provided on the end face of the saturable absorber 4, but the fourth reflective layer R4 may be arranged on the rear side of the saturable absorber 4 on the optical axis.
- the rearward direction of the optical axis is the direction in which light is emitted on the optical axis. That is, the fourth reflective layer R4 does not necessarily have to be provided inside or on the surface of the saturable absorber 4.
- FIG. A fourth reflective layer R4 is an output coupling mirror in the second resonator 12 .
- the solid-state laser medium 3 includes, for example, Yb (yttrium)-doped YAG (yttrium aluminum garnet) crystal Yb:YAG.
- the first wavelength ⁇ 1 of the first resonator 11 is 940 nm
- the second wavelength ⁇ 2 of the second resonator 12 is 1030 nm.
- the solid-state laser medium 3 is not limited to Yb:YAG. :SFAP, Yb:YVO, Yb:glass, Yb:KYW, Yb:BCBF, Yb:YCOB, Yb:GdCOB, YB:YAB can be used.
- the morphology is not limited to crystals, which does not prevent the use of ceramic materials.
- the solid-state laser medium 3 may be a four-level solid-state laser medium 3 or a quasi-three-level solid-state laser medium 3 .
- first wavelength ⁇ 1 the appropriate excitation wavelength
- the saturable absorber 4 includes, for example, Cr (chromium)-doped YAG (Cr:YAG) crystal.
- the saturable absorber 4 is a material whose transmittance increases when the intensity of incident light exceeds a predetermined threshold.
- the excitation light of the first wavelength ⁇ 1 from the first resonator 11 increases the transmittance of the saturable absorber 4 and emits a laser pulse of the second wavelength ⁇ 2. This is called a Q-switch.
- V:YAG can also be used as the material of the saturable absorber 4 .
- other types of saturable absorbers 4 may be used. Moreover, it does not prevent using an active Q switch element as the Q switch.
- excitation light source 2 solid-state laser medium 3, and saturable absorber 4 are shown separately in FIG.
- bonding processes include surface activated bonding, atomic diffusion bonding, plasma activated bonding, and the like. Alternatively, other bonding (adhesion) processes can be used.
- the electrodes E1 and E2 for injecting current into the first reflective layer R1 and the fifth reflective layer R5 are preferably arranged so as not to be exposed on the surface of the n-GaAs substrate 5 at least. .
- electrodes E1 and E2 are arranged on the end face of the excitation light source 2 on the first reflective layer R1 side.
- the electrode E1 is a p-electrode and is electrically connected to the first reflective layer R1.
- the electrode E2 is an n-electrode, and is formed by filling the inner wall of a trench extending from the first reflective layer R1 to the n-contact layer 33 with a conductive material 35 with an insulating film 34 interposed therebetween.
- this end face can be soldered to a support substrate (not shown). Even when a plurality of laser elements are arranged in an array, by arranging the electrodes E1 and E2 on the same end surface, this end surface can be mounted on the support substrate. Note that the shape and location of the electrodes E1 and E2 shown in FIG. 1 are merely examples.
- the arithmetic mean roughness Ra of each surface layer must be about 1 nm or less, preferably 0.5 nm or less. Chemical mechanical polishing (CMP) is used to achieve surface layers with these arithmetic mean roughnesses.
- CMP Chemical mechanical polishing
- a dielectric multilayer film may be arranged between the layers and the layers may be joined via the dielectric multilayer film.
- the GaAs substrate 5, which is the base substrate of the excitation light source 2 has a refractive index n of 3.2 for a wavelength of 940 nm, which is higher than YAG (n: 1.7) and general dielectric multilayer materials.
- an antireflection film (AR coating film or non-reflection coating film) that does not reflect the light of the first wavelength ⁇ 1 of the first resonator 11 is arranged between the excitation light source 2 and the solid-state laser medium 3. is desirable. It is also desirable to dispose an antireflection film (AR coating film or non-reflection coating film) between the solid-state laser medium 3 and the saturable absorber 4 as well.
- polishing may be difficult.
- a material transparent to the first wavelength ⁇ 1 and the second wavelength ⁇ 2 such as SiO 2
- SiO 2 is deposited as a base layer for bonding, and this SiO 2 layer is processed by arithmetic. It may be polished to an average roughness Ra of about 1 nm (preferably 0.5 nm or less) and used as an interface for bonding.
- materials other than SiO 2 can be used as the underlayer, and the material is not limited here.
- a non-reflective film may be provided between the SiO 2 material of the underlayer and the base layer.
- Dielectric multilayer film includes short wavelength transmission filter film (SWPF: Short Wave Pass Filter), long wavelength transmission filter film (LWPF: Long Wave Pass Filter), band pass filter film (BPF: Band Pass Filter), non-reflection protection
- SWPF Short Wave Pass Filter
- LWPF Long Wave Pass Filter
- BPF Band Pass Filter
- a film Anti-Reflection
- a PVD (Physical vapor deposition) method can be used as a method for forming the dielectric multilayer film, and specifically, a film forming method such as vacuum deposition, ion-assisted deposition, or sputtering can be used.
- the second reflective layer R2 may be a short wavelength transmission filter film
- the third reflective layer R3 may be a long wavelength transmission filter film.
- short wavelength transmission means that the light of the first wavelength ⁇ 1 is transmitted and the light of the second wavelength ⁇ 2 is reflected.
- long wavelength transmission means reflecting light of the first wavelength ⁇ 1 and transmitting light of the second wavelength ⁇ 2.
- a polarizer having a photonic crystal structure for separating the ratio of P-polarized light and S-polarized light may be provided inside the second resonator 12 .
- a diffraction grating may be provided inside the second resonator 12 to convert the polarization state of the emitted laser pulse from random polarization to linear polarization.
- the fine grooves of the photonic crystal structure and the diffraction grating can be used as an interface for bonding by forming a film of a material such as SiO 2 and polishing the film.
- the output of the spontaneous emission light increases, and when it exceeds a certain threshold, the saturable absorber The light absorptance at 4 drops abruptly, and the spontaneous emission light generated in the solid-state laser medium 3 becomes able to pass through the saturable absorber 4 .
- the light of the first wavelength ⁇ 1 emitted from the first resonator 11 is emitted from the solid-state laser medium 3, and the light of the second wavelength ⁇ 1 is emitted from the second resonator 12 between the second reflective layer R2 and the fourth reflective layer R4. Resonate the light of ⁇ 2.
- Q-switched laser oscillation occurs, and a Q-switched laser pulse is emitted toward space (the space on the right side in FIG. 1) via the fourth reflective layer R4.
- a nonlinear optical crystal for wavelength conversion can be arranged inside the second cavity 12 .
- the wavelength of the laser pulse after wavelength conversion can be changed.
- wavelength conversion materials include nonlinear optical crystals such as LiNbO 3 , BBO, LBO, CLBO, BiBO, KTP, and SLT. Phase-matching materials similar to these may also be used as the wavelength conversion material. However, any kind of wavelength conversion material is acceptable.
- the wavelength converting material can convert the second wavelength ⁇ 2 to another wavelength.
- the heat exhaust part is, for example, a transparent material that can transmit light of the first wavelength and has a higher thermal conductivity than the solid-state laser medium 3 .
- YAG with a thermal conductivity of 17 W/(m ⁇ K) is often used as the material of the solid-state laser medium 3 .
- the substrate size in the direction perpendicular to the optical axis of the solid-state laser medium 3 is sufficiently larger than the beam diameter (100 ⁇ m) (for example, several mm), the temperature gradient in the plane of the solid-state laser medium 3 is growing.
- sapphire has a thermal conductivity of 40 W/(m ⁇ K), which is higher than that of YAG and has a refractive index and thermal expansion coefficient equivalent to those of YAG.
- CVD diamond with a thermal conductivity of 1000 W/(m ⁇ K) or SiC with a thermal conductivity of 200 W/(m ⁇ K) may be used.
- the material is not limited to a specific material.
- a supporting member for example, having a thermal conductivity of 400 W/(m K)
- a supporting member for example, having a thermal conductivity of 400 W/(m K)
- the heat exhaust part is arranged between the excitation light source 2 made up of laminated semiconductor layers and the solid-state laser medium 3, the advantage of the compact integrated structure is maintained, and the laser light is emitted by thermal interference. A decrease in oscillation efficiency and a decrease in optical wavelength conversion efficiency can be prevented.
- Mode coupling is achieved by making the transverse mode, which is the beam intensity distribution of the first wavelength of the first resonator 11, and the transverse mode, which is the beam intensity distribution of the second wavelength of the second resonator 12, substantially identical, It may be necessary to maximize the output of the oscillated light by the second resonator 12 . Therefore, it is desirable that the thickness of the heat exhaust portion 13 between the excitation light source 2 and the solid-state laser medium 3, which forms a part of the cavity length of the first cavity 11, takes into account the cooling efficiency and the transverse mode coupling efficiency. .
- the transverse mode which is the beam intensity distribution of the first wavelength of the first resonator 11
- the transverse mode which is the beam intensity distribution of the second wavelength of the second resonator 12
- Adjusting only the thickness may increase the thickness. This lengthens the first cavity 11 and causes diffraction loss of the first wavelength. Moreover, the total length of the laser element 1 is also increased.
- the first wavelength can be obtained without impairing the cooling performance and without increasing the length of the first cavity 11.
- the transverse mode, which is the beam intensity distribution, and the transverse mode, which is the beam intensity distribution of the second wavelength of the second resonator 12, can be efficiently coupled, and the output of oscillation light can be maximized.
- the excitation light source 2 is made of a material with a small bandgap, optical damage due to multiphoton absorption by short-pulse laser light is likely to occur.
- a plurality of short-wavelength transmission filter films (SWPF) are arranged at a plurality of interfaces between the pumping light source 2 and the solid-state laser medium 3 while shortening the cavity length so that the return light can be transmitted to the pumping light source 2. It is advisable not to enter.
- FIG. 2 is a schematic cross-sectional view of the laser device 1 provided with the heat exhaust portion 13 according to the first embodiment. 2 is mounted on a submount substrate 91, and the submount substrate 91 is mounted on a support substrate 92. As shown in FIG.
- the laser device 1 includes an excitation light source 2 composed of laminated semiconductor layers, a heat exhaust section 13 , a solid-state laser medium 3 , and a cooling member (second member) 14 .
- the excitation light source 2 in FIG. 2 has, for example, the same layer configuration as the excitation light source 2 in FIG. 1, but illustration of the detailed layer configuration is omitted in FIG.
- illustration of the detailed layer configuration is omitted in FIG.
- the laser device 1 in FIG. 2 does not have the saturable absorber 4 in FIG.
- the second resonator 12 resonates light of the second wavelength ⁇ 2 between the second reflective layer R2 and the fourth reflective layer R4 in the solid-state laser medium 3, unlike in FIG.
- the fourth reflective layer R4 is arranged on the second surface F2 of the solid-state laser medium 3, or is arranged on the rear side of the optical axis from the second surface F2.
- the heat exhaust section 13 has, for example, a heat exhaust member (first member) 17 made of a material having higher thermal conductivity than the solid-state laser medium 3 .
- the material of the heat exhaust member 17 is, for example, sapphire, diamond, or the like, but is not limited to a specific material.
- the excitation light source 2, the heat exhaust part 13, and the solid-state laser medium 3 are arranged on the same optical axis.
- a cooling member 14 is joined to each side surface of the excitation light source 2 , the heat exhaust section 13 , and the solid-state laser medium 3 .
- the cooling member 14 is made of a metal material with high thermal conductivity such as Cu.
- the cooling member 14 dissipates heat transferred from the excitation light source 2 and the solid-state laser medium 3 to the heat exhaust section 13 .
- the cooling member 14 may be joined to a package (not shown) to radiate heat using the package.
- the heat generated by the excitation light source 2 and the solid-state laser medium 3 is transferred to the heat exhaust section 13 .
- the exhaust heat unit 13 exhausts heat from the excitation light source 2 and the solid-state laser medium 3 to the cooling member 14 . Thereby, the temperature rise of the excitation light source 2 and the solid-state laser medium 3 can be suppressed. Therefore, according to the laser device 1 of FIG. It is possible to prevent the deterioration of the conversion efficiency of the light wavelength in the .
- the heat exhausting part 13 may be an air gap provided between the excitation light source 2 and the solid-state laser medium 3 instead of providing the heat exhausting member 17 .
- the cooling member 14 has not only the function of cooling the excitation light source 2 and the solid-state laser medium 3, but also the function of supporting the excitation light source 2 and the solid-state laser medium 3 while maintaining an air gap. Although air exists in the air gap portion, the thermal conductivity of the air is lower than that of the excitation light source 2 and the solid-state laser medium 3. Therefore, heat transfer between the excitation light source 2 and the solid-state laser medium 3 can be suppressed, and thermal interference between the excitation light source 2 and the solid-state laser medium 3 can be prevented.
- FIG. 3 is a schematic cross-sectional view of the laser device 1 provided with the heat exhaust portion 13 according to the second embodiment.
- the laser device 1 of FIG. 3 is obtained by adding a saturable absorber 4 to the laser device 1 of FIG. As shown in FIG. 3, the saturable absorber 4 is bonded to the end surface of the solid-state laser medium 3 .
- the second resonator 12 in the laser device 1 of FIG. 3 has a second resonator 12 between the second reflective layer R2 in the solid-state laser medium 3 and the fourth reflective layer R4 in the saturable absorber 4, as in FIG. Light with two wavelengths ⁇ 2 is resonated.
- the laser device 1 in FIG. 3 includes the heat exhausting section 13 similar to that in FIG. 2, thermal interference between the excitation light source 2 and the solid-state laser medium 3 can be suppressed.
- FIG. 4 is a schematic cross-sectional view of the laser device 1 provided with the heat exhaust portion 13 according to the third embodiment.
- the heat exhaust part 13 has a two-layer structure, and a metal layer 18 having high thermal conductivity such as Cu is arranged on the surface of the heat exhaust member 17 such as sapphire.
- the metal layer 18 is formed on the heat exhaust member 17 by vapor deposition, sputtering, or the like, for example.
- the cooling member 14 Since the cooling member 14 is bonded to the cooling member 14 , the heat exhausting part 13 , and the side surface of the solid-state laser medium 3 , by disposing the metal layer 18 on the surface of the heat exhausting member 17 , the heat from the solid-state laser medium 3 can be reduced. Heat can be efficiently transferred to the heat exhaust member 17 and the cooling member 14 via the metal layer 18, and the heat exhaust performance of the heat exhaust part 13 is further improved. However, since heat is generated when light of the first wavelength is absorbed in the metal layer, it is necessary to avoid the optical path of the first wavelength.
- the saturable absorber 4 may be joined to the end face of the solid-state laser medium 3, as in FIG.
- FIG. 5 is a schematic cross-sectional view of the laser device 1 provided with the heat exhaust portion 13 according to the fourth embodiment.
- the laser element 1 of FIG. 5 differs from the first to third embodiments in the structure of the heat exhaust portion 13 .
- the heat exhaust part 13 of FIG. 5 has a first region 13a and a second region 13b.
- the first area 13 a is an area including the optical axis and is arranged substantially in the center of the heat exhaust section 13 .
- the first region 13a is a region that transmits light of a first wavelength.
- the first region 13a may be a transparent material layer that transmits light of the first wavelength, or may be a simple air gap.
- the second region 13 b is arranged around the first region 13 a and has a higher thermal conductivity than the solid-state laser medium 3 .
- the second region 13b may be arranged as a plurality of vias.
- the first region 13a is an air gap
- the second region 13b functions as a spacer member for supporting the air gap of the first region 13a.
- the second region 13b is an insulating material or a metal material, and is made of, for example, a material with high thermal conductivity such as sapphire or diamond.
- the heat generated by the excitation light source 2 and the solid-state laser medium 3 is exhausted in the second region 13b in the heat exhausting section 13.
- the second region 13 b is joined to the excitation light source 2 and the solid-state laser medium 3 and is also joined to the cooling member 14 , so that the heat transferred from the excitation light source 2 and the solid-state laser medium 3 is discharged to the cooling member 14 . can be heated.
- the second region 13b may be formed in an annular shape so as to surround the first region 13a, or may be formed with a plurality of vias.
- FIG. 6 is a schematic cross-sectional view of the laser device 1 provided with the heat exhaust portion 13 according to the fifth embodiment.
- current is injected into the active layer 7 of the laser device 1 through the bonding wire 16.
- Bonding wires 16 are typically covered with a protective layer to prevent disconnection.
- the protective layer of the bonding wire 16 and the cooling member 14 are integrated. This integrated member is hereinafter referred to as a cooling member 14 .
- the protective layer of bonding wire 16 in FIG. 6 is preferably covered with an insulating material.
- a resin material, a glass material, or the like is known as an insulating coating material, and is not limited to a specific material as long as it is an insulating material.
- the cooling member 14 is not limited to a specific material as long as the material has a higher thermal conductivity than the solid-state laser medium 3 .
- a protective layer may be provided so as to cover the side surface of the cooling member in FIG. 5 and the bonding wire 16 .
- the protective layer is provided separately from the cooling member.
- FIG. 7 is a schematic cross-sectional view of the laser device 1 provided with the heat exhaust portion 13 according to the sixth embodiment.
- the laser element 1 of FIG. 7 differs from the heat exhausting section 13 of FIGS. 2 and 4 in the layer structure of the heat exhausting section 13 .
- the heat exhaust part 13 of FIG. 7 has a protective layer 19 laminated on the surface of the side facing the laminated semiconductor layer 2 .
- the protective layer 19 functions as a layer that transmits light of the first wavelength ⁇ 1 and reflects light of the second wavelength ⁇ 2.
- FIG. 8 is a schematic cross-sectional view of the laser device 1 provided with the heat exhaust portion 13 according to the seventh embodiment. Part of the energy of the excitation light absorbed by the solid-state laser medium 3 in the laser device 1 according to the present disclosure is converted into heat, increasing the temperature of the solid-state laser medium 3 . At that time, a temperature distribution is generated in the solid-state laser medium 3, and a refractive index distribution is generated along with the temperature distribution.
- the laminated semiconductor layer forming the first resonator is made of a material with a small bandgap, leakage light of the laser light of the second wavelength ⁇ 2 generated in the second resonator 12 is emitted into the first resonator. Once inside, optical damage due to multiphoton absorption is likely to occur.
- the laser element 1 of FIG. 8 includes an optical element 41 that widens the beam diameter of the laser light of the second wavelength ⁇ 2 generated in the second resonator 12, in addition to the heat exhausting section 13. As shown in FIG. The optical element 41 is arranged between the second reflective layer R2 and the fourth reflective layer R4 of the solid-state laser medium 3 .
- the fourth reflective layer R4 is arranged on the end surface of the solid-state laser medium 3 on the light emitting surface side or on the rear side of the optical axis from this end surface.
- the laser device 1 includes the saturable absorber 4
- the end face of the saturable absorber 4 on the side of the light emitting surface or the end face on the rear side of the optical axis is arranged.
- the optical element 41 reflects or refracts at least part of the light of the second wavelength ⁇ 2 so that the light of the second wavelength ⁇ 2 is not condensed. More specifically, the optical element 41 is a convex mirror that reflects at least part of the incident light or a light refracting mirror that refracts at least part of the incident light so that the incident light is not condensed. It is a member.
- FIG. 8 shows an example in which an optical element 41 is provided on the end surface of the saturable absorber 4 on the light exit surface side.
- the optical element 41 is formed by processing the end face of the base material of the material that transmits light of the first wavelength and the second wavelength ⁇ 2 on the side of the solid-state laser medium 3 into a concave shape, and forming, for example, a multilayer film along the concave surface to form a convex mirror. 42 are placed.
- This convex mirror 42 functions as the fourth reflective layer R4 of the second resonator 12 .
- the light of the second wavelength ⁇ 2 incident on the convex mirror 42 is reflected so as not to be condensed.
- the beam diameter of the light of the second wavelength ⁇ 2 in the second cavity 12 can be widened, the peak power of the laser light can be lowered, and optical damage occurs in the solid-state laser medium 3 and the excitation light source 2. become difficult.
- the heat exhaust member 17 is provided on the lower surface of the convex mirror 42, and the side of the heat exhaust member 17 joined to the convex mirror 42 is processed into a concave shape.
- FIG. 9 is a schematic cross-sectional view of a laser device 1 provided with a heat exhaust portion 13 according to an eighth embodiment.
- the heat exhausting part 13 in the laser device 1 of FIG. 9 has a heat exhausting member 17 having a positive cooling function.
- the heat exhaust member 17 has the function of containing and circulating the coolant 17a.
- the optical axis of the excitation light is made a transparent member, and a heat pipe 17b containing the coolant is provided around it. form is conceivable.
- the coolant 17a may be liquid or gas.
- FIG. 10 is a schematic cross-sectional view of a laser device 1 having a heat exhaust portion 13 according to the ninth embodiment.
- the laser element 1 of FIG. 10 includes a light control member (polarization control element) 43 in addition to the heat exhaust section 13 .
- the light control member 43 is arranged, for example, between the solid-state laser medium 3 and the saturable absorber 4 or on the rear side of the optical axis relative to the saturable absorber 4 .
- the light control member 43 controls the refraction, diffraction or polarization direction of the light of the second wavelength ⁇ 2. More specifically, the light control member 43 is, for example, a photonic crystal layer.
- a photonic crystal layer is a layer whose refractive index changes periodically. Also, either P-polarized light or S-polarized light can be selected in the photonic crystal layer.
- the light control member 43 may be a diffraction grating.
- the light control member 43 may have a fine periodic structure. More specifically, the fine periodic structure is, for example, a Fresnel lens, a metasurface structure, or a photonic crystal lens.
- the refraction, diffraction, or polarization direction of the light of the second wavelength ⁇ 2 can be controlled by adjusting the period and size of the unevenness forming the fine periodic structure.
- FIGS. 11A to 11C are diagrams schematically showing the planar shape of the heat exhaust portion 13 according to the tenth embodiment.
- the heat exhaust part 13 shown in FIGS. 11A to 11C has the heat exhaust part 13 according to any one of the above-described first to eighth forms as a basic structure, and additional technical features are added to the basic structure.
- the optical axis of the laser beam is arranged at the center position of the cooling member 14 having a polygonal planar shape.
- a heat exhaust member 17 such as sapphire may be arranged around the optical axis of the laser beam, or an air gap may be used.
- the planar shape of the cooling member 14 is a regular n-gon (n is an integer of 3 or more), and the center position of the regular n-gon is the optical axis of the laser element 1.
- the optical axis of the laser beam is arranged at the center position of the cooling member 14 having a circular planar shape.
- FIG. 12 is a schematic cross-sectional view of a laser array 44 in which a plurality of lens elements are arranged one-dimensionally or two-dimensionally.
- FIG. 12 shows an example in which each lens element has a heat exhausting section 13 having a structure similar to that of FIG.
- the heat-dissipating portions 13 of the plurality of lens elements are integrally joined.
- the heat exhaust part 13 having an integral structure has a heat exhaust member 17 .
- a cooling member 14 is bonded to the side surface of the lens array having a plurality of lens elements.
- the cooling member 14 is joined to the heat exhausting member 17 .
- the heat generated by the excitation light source 2 and the solid lens medium in each lens element is transferred to the heat exhaust member 17 and radiated from the heat exhaust member 17 to the cooling member 14 .
- FIG. 13A, 13B, 13C, and 13D are diagrams showing the temperature distribution of the laser light sources at the center and corners of the laser array 44 with and without the heat exhaust section 13.
- FIG. 13A and 13B show the temperature distribution of the laser light source in the central part of the laser array 44.
- FIG. showing. 13C and 13D show the temperature distribution of the laser light sources at the corners of the laser array 44.
- FIG. indicates the case.
- the horizontal axis of FIGS. 13A to 13D indicates the position on the optical axis of the laser element 1, the fourth reflective layer R4 side of the solid-state laser medium 3 is on the left side of the horizontal axis, and the support substrate 92 side is on the right side of the horizontal axis. is.
- the vertical axis of FIGS. 13A to 13D is the temperature at each position.
- 13A and 13C show the temperature distribution w1 of the laser device 1 without the heat exhaust portion 13.
- FIG. 13B and 13D show temperature distributions w2 to w5 of four types of laser elements 1 having different heat exhaust portions 13, respectively.
- the temperature distribution w2 is for the heat removal part 13 having the heat removal member 17 made of sapphire
- the temperature distribution w3 is for the heat removal part 13 having the heat removal member 17 made of sapphire and the cooling member 14
- the cooling member 14 is a copper wall joined to the side surfaces of the excitation light source 2 , the heat exhaust section 13 and the solid-state laser medium 3 .
- the temperature of the central laser element 1 is generally higher than that of the corners of the laser array 44, whether or not there is the heat exhausting section 13 .
- the heat exhausting portion 13 having the heat exhausting member 17 made of diamond and the laser element 1 (temperature distribution w5) having the cooling member 14 have the greatest temperature reduction effect.
- the next largest temperature reduction effect is the laser element 1 (temperature distribution w4) provided with the heat exhaust part 13 having the heat exhaust member 17 made of sapphire and the cooling member 14, and the temperature reduction effect is next. is large in the laser element 1 (temperature distribution w3) in the heat exhausting section 13 having the heat exhausting member 17 made of sapphire and without the cooling member 14 .
- the laser element 1 (temperature distribution w2) provided with the heat exhausting part 13 formed of the air gap and the cooling member 14 has the smallest temperature reduction effect, but the laser element 1 without the air gap ( The temperature can be lower than the temperature distribution w1). Therefore, the heat exhaust part 13 can obtain a certain effect of suppressing the temperature rise in the laser element 1 only by the air gap.
- the second resonator 12 emits a laser pulse of the second wavelength ⁇ 2 by Q-switching, there is a possibility that the oscillation light of the second wavelength ⁇ 2 with high peak intensity may enter the excitation light source 2 as return light. Since the excitation light source 2 is made of a semiconductor material with a small bandgap, it may be destroyed by return light. For this reason, a plurality of short-wavelength transmission filter films (SWPF), which are the heat exhaust part 13 and the protective layer 19, are arranged between the excitation light source 2 and the solid-state laser medium 3 while shortening the cavity length. It is desirable to prevent return light from entering the excitation light source 2 .
- SWPF short-wavelength transmission filter films
- FIG. 14 is a diagram schematically showing the manufacturing process of the laser device 1 of the present disclosure.
- FIG. 14 shows the manufacturing process of the laser element 1 having the optical element 41 for avoiding optical damage and the saturable absorber 4 shown in FIG.
- FIG. 14 shows an example in which a convex mirror 42 for an optical element 41 is formed on the upper surface side of the saturable absorber.
- a resist film 21 is applied onto a transparent substrate 45 for an optical element 41 placed on the saturable absorber 4, and a photomask is applied onto the resist film 21. 22 is placed and UV exposure is performed.
- step S2 the exposed portions and the resist film 21 are removed by dry etching or the like to form a plurality of recesses 23 on the upper surface of the transparent base material 45.
- step S2 the exposed portions and the resist film 21 are removed by dry etching or the like to form a plurality of recesses 23 on the upper surface of the transparent base material 45.
- step S2 the exposed portions and the resist film 21 are removed by dry etching or the like to form a plurality of recesses 23 on the upper surface of the transparent base material 45.
- a dielectric multilayer film 24 is formed in the plurality of concave portions 23 by vapor deposition, sputtering, or the like, and convex mirrors 42 are formed.
- step S3 the laminated semiconductor layer 2 for the excitation light source 2, the heat exhaust member 17, the solid-state laser medium 3, and the saturable absorber 4 processed in step S2 are vertically arranged. to align.
- the heat exhaust member 17 is formed by forming a film of sapphire, diamond, or the like on the upper surface of the laminated semiconductor layer 2 by vapor deposition or sputtering before step S3.
- step S4 the alignment marks 25 provided at respective specific locations of the semiconductor layer 2, the solid-state laser medium 3, and the saturable absorber 4 are photographed with a camera 26 so that the alignment marks 25 are not visible.
- the semiconductor layer 2, the solid-state laser medium 3 and the saturable absorber 4 are aligned and bonded so as to overlap each other.
- step S5 individual laser elements are separated by dicing.
- the heat generated by the excitation light source 2 and the solid-state laser medium 3 can be removed by the heat exhaust member.
- the heat can be radiated to the cooling member 14 via 17, and the temperature rise in the laser element 1 can be suppressed.
- the first resonator 11 and the second resonator 12 share the solid-state laser medium 3 .
- the light transmitting surfaces of all the optical parts including the excitation light source 2, the solid-state laser medium 3, and the saturable absorber 4 in the laser device 1 are bonded and fixed by a bonding process.
- the temperature rise in the laser element 1 can be suppressed.
- the reliability and productivity of the laser device 1 are improved, and the laser device 1 can be obtained at a low cost and with high performance.
- the solid-state laser medium 3 is joined to the excitation light source 2 , the solid-state laser medium 3 is excited by standing waves within the excitation light source 2 .
- the solid-state laser medium 3 is thick enough to absorb the pumping light when the laser beam passes through the first resonator 11 only once. Even if there is no laser light, the excitation light can be sufficiently absorbed by the solid-state laser medium 3 as a result of the laser light reciprocating many times. As a result, shorter pulse Q-switched laser oscillation can be performed without lowering pumping efficiency.
- the solid-state laser medium 3 is excited by traveling waves, and the method of excitation is significantly different from that of the laser element 1 according to the present disclosure.
- the above-described trade-off that the amount of excitation light absorbed is reduced when the solid-state laser medium 3 is shortened can be resolved.
- the laser device 1 of the present disclosure short-term and long-term fluctuations in laser output due to mechanical displacement can be suppressed by directly bonding the light transmitting surfaces of the optical components.
- all the optical parts can be joined and then diced into individual laser light sources, mass productivity can be improved.
- the pumping light source 2 and the second resonator 12 are five-axis optical adjustment (X, Y, Z, ⁇ , ⁇ ) with respect to the optical axis, eccentricity, and focus using a plurality of lenses including a collimator lens and a condenser lens. I do. Further, if an optical element 9 having a beam divergence function (negative refractive power) is added to the second resonator 12, it becomes more difficult to adjust the position of the optical element 9 with high accuracy.
- the laser element 1 in order to align the light emitting point of the excitation light source 2 and the center position of the convex mirror 42 of the optical element 9 without using a plurality of lenses of the collimator lens and the condenser lens, By performing the bonding using the alignment mark 25 or the like, there is no need to adjust the focus position accuracy in the thickness (Z-axis) direction or the inclination in the ⁇ and ⁇ directions. Therefore, according to the laser device 1 of the present disclosure, it is possible to suppress short-term and long-term fluctuations in laser output, facilitate optical adjustment for obtaining oscillation light from the excitation light source 2, and improve mass productivity. It is possible to realize a light source with
- the laser device 1 according to the present disclosure employs an integrated laminated structure such that the optical axis of the first resonator 11 and the optical axis of the second resonator 12 are coaxial.
- the laser device 1 according to the present disclosure does not require complicated positional and angular alignments, and has a simplified structure. Therefore, it becomes easy to miniaturize the laser element 1 .
- a plurality of laser elements 1 according to the present disclosure can be formed at the same time.
- high-performance laser elements 1 can be mass-produced at low cost.
- a laser array 44 in which a plurality of laser devices 1 are two-dimensionally arranged on one substrate can be easily manufactured.
- the repetition frequency of the laser pulse can be adjusted depending on the type of the solid-state laser medium 3.
- the repetition frequency of laser pulses can be increased.
- the resonator length can be changed only by adjusting the thicknesses of the solid-state laser medium 3, Q switch (saturable absorber 4), and wavelength conversion material (nonlinear optical crystal). can. That is, since the pulse time width of the laser pulse can be changed according to the thickness of the material, the characteristics of the laser pulse can be easily adjusted. In particular, by shortening the pulse time width of the laser pulse, it is possible to increase the processing accuracy in the field of fine processing.
- the laser elements 1 according to the present disclosure can be arranged in a one-dimensional array or a two-dimensional array, it is possible to obtain a laser device that achieves both high processing accuracy and high output energy.
- the laser device 1 according to the present disclosure can be applied to other fields such as highly efficient wavelength conversion technology, medical equipment, and distance measurement.
- the laser device 1 in FIG. 1 shows an example in which the excitation light source 2, the solid-state laser medium 3, and the saturable absorber 4 are integrally bonded, as shown in FIG. 3, a first transparent medium 27 that transmits light of the first wavelength ⁇ 1 may be arranged.
- a second transparent medium 28 that transmits light of the second wavelength ⁇ 2 may be arranged between the solid-state laser medium 3 and the saturable absorber 4 . Only one of the first transparent medium 27 and the second transparent medium 28 may be arranged.
- the excitation light source 2, the solid-state laser medium 3, and the saturable absorber 4 do not necessarily have to be integrally joined.
- the optical element 9 may be arranged on the rear side of the optical axis relative to the saturable absorber 4, as shown in FIG.
- a convex mirror 42 is formed by processing a transparent member 29 that transmits light of the second wavelength ⁇ 2 into a concave shape.
- the optical axis of the excitation light source 2, the optical axis of the solid-state laser medium 3, the optical axis of the saturable absorber 4, and the optical axis of the optical element 9 need to be arranged on the same axis. be.
- FIG. 1 shows an example in which the laser device 1 has a saturable absorber 4 and emits short-pulse pulsed laser light. 1, thermal interference may occur between the excitation light source 2 and the solid-state laser medium.
- FIG. 16 is a diagram showing the basic configuration of the laser device 1 without the saturable absorber 4.
- FIG. A laser device 1 in FIG. 16 has a configuration in which the saturable absorber 4 is omitted from FIG.
- the first resonator 11 resonates light of the first wavelength ⁇ 1 between the first reflective layer R1 in the excitation light source 2 and the third reflective layer R3 in the solid-state laser medium 3, as in FIG.
- the second resonator 12 resonates the light of the second wavelength ⁇ 2 between the second reflective layer R2 and the fourth reflective layer R4 in the solid-state laser medium 3 .
- the fourth reflective layer R4 is arranged on the second surface F2 of the solid-state laser medium 3, or is arranged on the rear side of the optical axis from the second surface F2.
- FIG. 16 shows an example in which a third reflective layer R3 and a fourth reflective layer R4 are separately provided along the second surface F2 of the solid-state laser medium 3.
- FIG. 16 when the fourth reflective layer R4 is arranged on the rear side of the optical axis relative to the third reflective layer R3, the third reflective layer R3 has the characteristic of transmitting light of the second wavelength ⁇ 2.
- the third reflective layer R3 is a highly reflective layer, while the fourth reflective layer R4 is a partially reflective layer. Therefore, the power of the pumping light of the first wavelength is confined within the solid-state laser medium 3, and when the solid-state laser medium 3 is sufficiently pumped to increase the output of the spontaneous emission light, the light of the second wavelength ⁇ 2 is emitted to the second wavelength. 4 It is emitted from the laser element 1 after passing through the reflective layer R4.
- the third reflective layer R3 and the fourth reflective layer R4 may be integrated into one reflective layer.
- the integrated reflective layer reflects light of the first wavelength and reflects light of the second wavelength ⁇ 2.
- the configuration in which the heat exhaust part 13 is provided between the excitation light source 2 and the solid-state laser medium 3 in the laser element 1 of FIG. 16 is, for example, those shown in FIGS. become.
- the structure of the laser device 1 according to the present disclosure described above can be applied to a laser amplification device.
- a laser amplification device Conventionally, short-pulse laser light is amplified by reducing the peak intensity of the amplified light in order to avoid optical damage.
- the chirped pulse amplification method in which the pulse width of the laser beam is expanded and then amplified, and then the pulse width is compressed, or the thin disk method, in which the laser beam is spatially expanded to reduce the peak intensity, are used.
- the thin disk method in which the laser beam is spatially expanded to reduce the peak intensity
- FIG. 17A is a perspective view showing the configuration of Innoslab
- FIG. 17B is a plan view of FIG. 17A viewed from the Y direction
- FIG. 17C is a plan view of FIG. 17A viewed from the Z direction.
- Innoslab has two excitation light sources 81 and 82 provided on both sides in the X direction, mirrors M1 to M6, an amplification medium 83, a polarizer 84, and a ⁇ /4 plate 85.
- Each excitation light source 81 , 82 has a laser array 86 , optical systems L 1 to L 3 and waveguide 87 .
- a weak light symmetrical to amplification (light to be amplified) is incident from the input portion IN.
- This light to be amplified reciprocates many times between the mirrors M2 and M5 while gradually shifting its path.
- the light to be amplified is amplified by stimulated emission in the amplification medium 83 each time it passes through the amplification medium 83 arranged between the mirrors M2 and M5, and finally the amplified laser light is emitted from the output section OUT. be.
- a plurality of laser arrays 86 in the excitation light sources 81 and 82 are stacked in the Z direction, and emit laser light planarly in the X direction.
- Laser light emitted from the laser array 86 in a planar shape is condensed by the cylindrical lens L1 and is incident on the waveguide 87 .
- the laser light emitted from the waveguide 87 is beam-shaped by the cylindrical lens L2 and the optical system L3 and is incident on the half mirror M4. A part of the laser light incident on the half mirror M4 is transmitted through the half mirror M4 and is incident on the amplification medium 83 .
- the amplification medium 83 has a thin plate shape (for example, 0.2 mm ⁇ 10 mm ⁇ 10 mm), and the light to be amplified is incident on the elongated rectangular end face.
- the light to be amplified is so-called seed light, which is a laser pulse emitted from a femtosecond laser or a picosecond laser oscillator.
- the Innoslab shown in Figures 17A to 17C has two advantages.
- the first advantage is that since the heat flux in the amplification medium 83 is one-dimensional, thermal lensing and thermal birefringence, which limit the amplification factor of laser light, do not occur. Thermal lenses and thermal birefringence occur remarkably in the rod-shaped amplifying medium 83, and have been the cause of limiting the amplification factor of laser light.
- the second advantage is that since the seed light is incident from the elongated rectangular end face described above, the beam shape of the seed light can be lengthened in the longitudinal direction, and the peak intensity in the amplification medium 83 can be spatially reduced. It is possible to avoid optical damage due to amplified light.
- Innoslab also has its drawbacks. As shown in FIGS. 17A to 17C, Innoslab generally adopts a configuration in which excitation is performed from both sides of the amplification medium 83, and the length in the longitudinal direction is nearly 1 m. This is because a complex beam-shaping optical system is required to shape the luminous flux of the edge-emitting LD module so that it fits the rectangular end face of the amplifying medium 83 .
- the amplification factor of laser light in Innoslab is determined by the area of the amplification medium 83 when the thickness thereof is constant. Determined. This is because the principle of the Innoslab system is a so-called end-pump type amplifier configuration, and there is a limit to the amplification factor of laser light that is determined by the optical absorption length of pumping light.
- the amplification medium 83 For example, if Yb:YAG is used as the amplification medium 83 and the wavelength of the pumping light is 940 nm, the pumping light is absorbed at about 5 mm from the incident surface of Yb:YAG. Since Yb:YAG is excited from both sides, the length of Yb:YAG is set to about 10 mm. If the length of Yb:YAG is longer than 10 mm, an unexcited region will occur inside the Yb:YAG. Therefore, in the amplification medium 83, only an amplification factor corresponding to a length determined by the absorption length of the excitation light can be obtained. Therefore, the upper limit of the amplification factor is determined by the size of the amplification medium 83, which is determined by the absorption length of the excitation light.
- FIG. 18A is a cross-sectional view of a laser amplifying element 50 according to the present disclosure
- FIG. 18B is a perspective view of the laser amplifying element 50 according to the present disclosure
- FIG. 18C is a plan view schematically showing the optical path of the laser light within the laser amplifying element 50. As shown in FIG.
- a laser amplification element 50 according to FIGS. 18A to 18C includes a pumping light source 53 arranged on a support substrate 51 via a submount substrate 52, and a solid-state laser medium 54 arranged above the pumping light source 53. , the saturable absorber 4 is not provided.
- the solid-state laser medium 54 is Yb:YAG, for example.
- the excitation light source 53 and the solid-state laser medium 54 constitute a first resonator 55, and light of the first wavelength is resonated in the vertical direction (stacking direction) of FIG. 18A.
- the first resonator 55 transmits light of the first wavelength between the first reflective layer R1 (p-DBR 72) in the excitation light source 53 and the second reflective layer R2 in the solid-state laser medium 54. to resonate.
- the solid-state laser medium 54 of FIG. 18A does not require a reflective layer on the end face facing the excitation light source 53, and has the second reflective layer R2 on the opposite end face.
- 18A to 18C includes a first reflecting member 56 and a second reflecting member 57 arranged along the opposed first side surface 54S1 and the second side surface 54S2 of the solid-state laser medium 54; and a solid-state laser medium 54 functioning as an amplification medium 83 for allowing the light of the second wavelength ⁇ 2 to reciprocate multiple times between the first reflecting member 56 and the second reflecting member 57 .
- the first reflecting member 56 and the second reflecting member 57 may have flat reflecting mirrors, or convex reflecting mirrors to avoid optical damage to the material when the light density increases in the process of amplification. may have
- the first reflecting member 56 and the second reflecting member 57 are arranged at a distance from the first side surface 54S1 and the second side surface 54S2 of the solid-state laser medium 54, but the first side surface 54S1 and the second side surface 54S2 Alternatively, a multilayer film may be formed by laminating at least one of a semiconductor material, a metal material, and a dielectric material, and these multilayer films may be used as the reflecting mirror.
- the laser amplification element 50 comprises an optical input portion IN provided along the first side surface 54S1 and an optical output portion OUT provided along the second side surface 54S2.
- the light input unit IN allows weak light (seed light) of the second wavelength ⁇ 2 to enter the first side surface 54S1.
- the light of the second wavelength ⁇ 2 reciprocates multiple times in the amplification medium 83 and is emitted from the optical output section OUT.
- the laser amplifying device 50 shown in FIGS. 18A to 18C may include a first heat exhaust member 60 and a second heat exhaust member 61.
- the first heat exhaust member 60 is disposed between the excitation light source 53 and the solid-state laser medium 54 and exhausts heat generated by at least one of the excitation light source 53 and the solid-state laser medium 54 .
- the second heat exhaust member 61 is joined to the end surface of the solid-state laser medium 54 opposite to the end surface facing the excitation light source 53 and exhausts the heat generated in the solid-state laser medium 54 .
- At least one of the first heat exhaust member 60 and the second heat exhaust member 61 may be omitted.
- the first heat exhaust member 60 and the second heat exhaust member 61 are made of a material having a higher thermal conductivity than the solid-state laser medium 54, such as sapphire or YAG.
- the first heat exhaust member 60 and the second heat exhaust member 61 are made of a transparent material that transmits the light of the first wavelength.
- the laser amplification element 50 according to FIGS. 18A to 18C may have a cooling member 62 .
- the cooling member 62 is joined to the side surfaces of the excitation light source 53, the first heat exhaust member 60, and the solid-state laser medium 54, and absorbs heat transferred from at least one of the excitation light source 53 and the solid-state laser medium 54 to the first heat exhaust member 60. to dissipate heat.
- the cooling member 62 is, for example, a metal material with high thermal conductivity such as Cu.
- the cooling member 62 may be joined to a package (not shown), and heat may be radiated from the cooling member 62 to the package.
- a support substrate 51 in the laser amplification element 50 shown in FIGS. 18A to 18C is, for example, a Cu substrate, and a submount substrate 52 is arranged thereon.
- the submount substrate 52 has, for example, a laminated structure of a SiC layer 64 and an AuSn layer 65.
- a p-electrode 73 and an n-electrode 74 of the excitation light source 53 are electrically insulated and bonded to each other. .
- the excitation light source 53 is a laminated semiconductor layer in which an n-contact layer 67, an n-DBR 68, a clad layer 69, an active layer 70, a clad layer 71, and a p-DBR 72 are laminated on an n-GaAs substrate 66 in this order.
- P-electrodes 73 and n-electrodes 74 are alternately arranged on the p-DBR 72 .
- the p-electrode 73 is electrically connected to the p-DBR 72 and the n-electrode 74 is electrically connected to the n-DBR 68 through the via 75 .
- the laser amplification element 50 has a first resonator 55, as in FIG.
- the first resonator 55 resonates light of the first wavelength between the first reflective layer R1 in the excitation light source 53 and the second reflective layer R2 in the solid-state laser medium 54 .
- the first reflective layer R1 is the p-DBR 72, and the second reflective layer R2 is arranged on the upper surface of the second heat exhaust member 61, for example.
- the solid-state laser medium 54 is excited by the resonance operation of the light of the first wavelength by the first resonator 55 .
- FIG. 18A the resonant operation of the first resonator 55 is schematically indicated by thin lines.
- Seed light Light to be amplified (seed light) of the second wavelength ⁇ 2 is made incident leftward from the right end of FIG. 18A into the solid-state laser medium 54 in the pumped state. This causes stimulated emission of the light to be amplified, and the light to be amplified is laser-amplified.
- Yb:YAG when used as the amplification medium 83, if a laser beam with a wavelength of 1030 nm is used as the seed light, it will be absorbed in an unexcited region in the amplification medium 83, resulting in insufficient amplification. happens. Therefore, when Yb:YAG is used as the amplification medium 83, it is possible to use seed light with a wavelength of 1050 nm, which does not cause light absorption even in a non-excited state. In this case, the wavelength of the seed light is not limited to 1050 nm as long as light absorption does not occur even in the non-excited state.
- the size of the solid-state laser medium 54 in the laser amplifying device 50 according to the present disclosure is not limited by the absorption length of the excitation light, the area of the solid-state laser medium 54 can be increased regardless of the absorption length of the excitation light. By increasing the area of the solid-state laser medium 54, the amplification factor of the laser amplification element 50 can be further improved.
- the laser amplification element 50 can integrally bond the pumping light source 53 made of the laminated semiconductor layer and the solid-state laser medium 54, and can be manufactured by a general-purpose semiconductor process, so miniaturization is easy. and can reduce manufacturing costs.
- the laser amplification element 50 since the first heat exhaust member 60 and the second heat exhaust member 61 are bonded to both surfaces of the solid-state laser medium 54, the temperature rise of the solid-state laser medium 54 can be suppressed. and the solid-state laser medium 54 can be prevented from thermally interfering with each other.
- FIG. 19A is a cross-sectional view of the laser amplification element 50 in which the heat exhaust performance of the first heat exhaust member 60 of FIG. 18A is improved.
- the first heat exhaust member 60 of FIG. 19A has a plurality of via members 76 that pass through the first heat exhaust member 60 and are joined to the excitation light source 53 and the solid-state laser medium 54 .
- These via members 76 are filled with a material having higher thermal conductivity than the base material of the first heat exhaust member 60 .
- FIG. 19B is a cross-sectional view along line AA in FIG. 19A.
- FIG. 19B shows an example in which a plurality of via members 76 are arranged at regular intervals in the two-dimensional direction, but the arrangement location, diameter size, and number of via members 76 are arbitrary. Since the thermal conductivity of the plurality of via members 76 is higher than that of the solid-state laser medium 54 , the heat transferred from the excitation light source 53 and the solid-state laser medium 54 to the via members 76 travels through the first heat exhaust member 60 . The heat is exhausted to the cooling member 62 via.
- the laser amplification element 50 shown in FIGS. 18A to 18C or 19A to 19B is composed of the first reflective layer R1 in the excitation light source 53 and the second reflective layer R2 in the solid-state laser medium 54.
- the first resonator 55 resonates the light of the first wavelength in the lamination direction to excite the solid-state laser medium 54, and in this state, the light of the second wavelength ⁇ 2 is emitted from the end surface of the solid-state laser medium 54.
- the light of the second wavelength ⁇ 2 is sufficiently amplified and emitted by making it enter in the horizontal direction and reflecting it many times between the two reflecting mirrors provided along the two facing end surfaces of the solid-state laser medium 54 . be able to.
- the pumping light source 53 and the solid-state laser medium 54 are integrated, and can be formed using semiconductor process technology. Despite its size, the solid-state laser medium 54 can be brought into an excited state. Further, the light of the second wavelength ⁇ 2 to be optically amplified is horizontally incident from the end surface of the solid-state laser medium 54, and the first reflecting members are arranged along the two opposing side surfaces 54S1 and 54S2 of the solid-state laser medium 54. Since the light of the second wavelength ⁇ 2 is amplified by repeating reflection by 56 and the second reflecting member 57, it is possible to amplify the light with a sufficient amplification factor in spite of its small size.
- a medical imaging system is a medical system using imaging technology, such as an endoscope system or a microscope system.
- FIG. 20 is a diagram showing an example of a schematic configuration of an endoscope system 5000 to which technology according to the present disclosure can be applied.
- FIG. 21 is a diagram showing an example of the configuration of an endoscope 5001 and a CCU (Camera Control Unit) 5039.
- FIG. 20 illustrates a state in which an operator (for example, a doctor) 5067 who is a surgical participant is performing surgery on a patient 5071 on a patient bed 5069 using an endoscope system 5000 .
- an operator for example, a doctor
- the endoscope system 5000 supports an endoscope 5001 as a medical imaging device, a CCU 5039, a light source device 5043, a recording device 5053, an output device 5055, and an endoscope 5001. and a support device 5027 .
- an insertion aid called a trocar 5025 is punctured into a patient 5071. Then, the scope 5003 and surgical instrument 5021 connected to the endoscope 5001 are inserted into the body of the patient 5071 via the trocar 5025 .
- the surgical instrument 5021 is, for example, an energy device such as an electric scalpel, forceps, or the like.
- a surgical image which is a medical image of the inside of the patient's 5071 photographed by the endoscope 5001, is displayed on the display device 5041.
- the operator 5067 uses the surgical instrument 5021 to treat the surgical target while viewing the surgical image displayed on the display device 5041 .
- the medical images are not limited to surgical images, and may be diagnostic images captured during diagnosis.
- the endoscope 5001 is an imaging unit for imaging the inside of the body of a patient 5071.
- a camera 5005 includes a zoom optical system 50052 that enables optical zoom, a focus optical system 50053 that enables focus adjustment by changing the focal length of an imaging unit, and a light receiving element 50054 .
- the endoscope 5001 converges light on the light receiving element 50054 through the connected scope 5003 to generate pixel signals, and outputs the pixel signals to the CCU 5039 through the transmission system.
- the scope 5003 is an insertion portion that has an objective lens at its tip and guides light from the connected light source device 5043 into the body of the patient 5071 .
- the scope 5003 is, for example, a rigid scope for rigid scopes and a flexible scope for flexible scopes.
- the scope 5003 may be a direct scope or a perspective scope.
- the pixel signal may be a signal based on a signal output from a pixel, such as a RAW signal or an image signal.
- a memory may be installed in the transmission system connecting the endoscope 5001 and the CCU 5039, and the parameters relating to the endoscope 5001 and the CCU 5039 may be stored in the memory.
- the memory may be arranged, for example, on the connection part of the transmission system or on the cable.
- the parameters of the endoscope 5001 at the time of shipment and the parameters changed when the power is supplied may be stored in the memory of the transmission system, and the operation of the endoscope may be changed based on the parameters read from the memory.
- an endoscope and a transmission system may be collectively referred to as an endoscope.
- the light receiving element 50054 is a sensor that converts received light into pixel signals, and is, for example, a CMOS (Complementary Metal Oxide Semiconductor) type imaging element.
- the light-receiving element 50054 is preferably an imaging element having a Bayer array and capable of color imaging.
- the light receiving element 50054 is, for example, 4K (horizontal pixel number 3840 ⁇ vertical pixel number 2160), 8K (horizontal pixel number 7680 ⁇ vertical pixel number 4320) or square 4K (horizontal pixel number 3840 or more ⁇ vertical pixel number 3840 or more). It is preferable that the image sensor has a number of pixels corresponding to the resolution.
- the light receiving element 50054 may be a single sensor chip or a plurality of sensor chips.
- a prism may be provided to separate the incident light into predetermined wavelength bands, and each wavelength band may be imaged by a different light-receiving element.
- a plurality of light receiving elements may be provided for stereoscopic vision.
- the light receiving element 50054 may be a sensor including an arithmetic processing circuit for image processing in a chip structure, or may be a ToF (Time of Flight) sensor.
- the transmission system is, for example, an optical fiber cable or wireless transmission. The wireless transmission is sufficient as long as the pixel signals generated by the endoscope 5001 can be transmitted.
- Mirror 5001 and CCU 5039 may be connected.
- the endoscope 5001 may transmit not only the pixel signal but also information related to the pixel signal (for example, processing priority of the pixel signal, synchronization signal, etc.) at the same time.
- the endoscope may be configured by integrating a scope and a camera, or by providing a light-receiving element at the tip of the scope.
- the CCU 5039 is a control device that comprehensively controls the connected endoscope 5001 and light source device 5043. For example, as shown in FIG. processing equipment. Also, the CCU 5039 may centrally control the connected display device 5041 , recording device 5053 and output device 5055 . For example, the CCU 5039 controls the irradiation timing and irradiation intensity of the light source device 5043 and the type of irradiation light source.
- the CCU 5039 performs image processing such as development processing (for example, demosaicing processing) and correction processing on the pixel signals output from the endoscope 5001, and outputs the processed pixel signals (for example, image processing) to an external device such as the display device 5041. ). Also, the CCU 5039 transmits a control signal to the endoscope 5001 to control driving of the endoscope 5001 .
- the control signal is, for example, information about imaging conditions such as magnification and focal length of the imaging unit.
- the CCU 5039 may have an image down-conversion function, and may be configured to output a high-resolution (eg, 4K) image to the display device 5041 and a low-resolution (eg, HD) image to the recording device 5053 at the same time.
- a high-resolution (eg, 4K) image to the display device 5041
- a low-resolution (eg, HD) image to the recording device 5053 at the same time.
- the CCU 5039 is connected to external devices (eg, recording device, display device, output device, support device) via an IP converter that converts signals into a predetermined communication protocol (eg, IP (Internet Protocol)).
- IP Internet Protocol
- the connection between the IP converter and the external device may be configured by a wired network, or part or all of the network may be configured by a wireless network.
- the IP converter on the CCU5039 side has a wireless communication function, and the received video is sent to an IP switcher or output via a wireless communication network such as the 5th generation mobile communication system (5G) or the 6th generation mobile communication system (6G). It may be sent to the side IP converter.
- 5G 5th generation mobile communication system
- 6G 6th generation mobile communication system
- the light source device 5043 is a device capable of emitting light in a predetermined wavelength band, and includes, for example, a plurality of light sources and a light source optical system that guides light from the plurality of light sources.
- the light source is, for example, a xenon lamp, an LED light source, or an LD light source.
- the light source device 5043 has, for example, LED light sources corresponding to the three primary colors R, G, and B, and emits white light by controlling the output intensity and output timing of each light source. Further, the light source device 5043 may have a light source capable of irradiating special light used for special light observation separately from the light source for irradiating normal light used for normal light observation.
- Special light is light in a predetermined wavelength band different from normal light that is light for normal light observation.
- Normal light is, for example, white light or green light.
- narrow-band light observation which is a type of special light observation, by alternately irradiating blue light and green light, the wavelength dependence of light absorption in body tissues can be used to detect specific tissues such as blood vessels on the surface of the mucous membrane. can be shot with high contrast.
- fluorescence observation which is a type of special light observation, excitation light that excites the drug injected into the body tissue is irradiated, and fluorescence emitted by the body tissue or the drug as a marker is received to obtain a fluorescence image.
- a drug such as indocyanine green (ICG) injected into the body tissue is irradiated with infrared light having an excitation wavelength band, and the fluorescence of the drug is received to detect the body tissue. structure and the affected area can be easily visualized.
- an agent for example, 5-ALA
- the light source device 5043 sets the type of irradiation light under the control of the CCU 5039 .
- the CCU 5039 may have a mode in which normal light observation and special light observation are alternately performed by controlling the light source device 5043 and the endoscope 5001 .
- information based on pixel signals obtained by special light observation is preferably superimposed on pixel signals obtained by normal light observation.
- the special light observation may be infrared light observation in which infrared light is irradiated to look deeper than the surface of the organ, or multispectral observation utilizing hyperspectral spectroscopy. Additionally, photodynamic therapy may be combined.
- a recording device 5053 is a device for recording pixel signals (for example, an image) obtained from the CCU 5039, and is, for example, a recorder.
- a recording device 5053 records the image acquired from the CCU 5039 on an HDD, an SDD, or an optical disc.
- the recording device 5053 may be connected to a hospital network and accessible from equipment outside the operating room. Also, the recording device 5053 may have an image down-conversion function or an image up-conversion function.
- the display device 5041 is a device capable of displaying an image, such as a display monitor.
- a display device 5041 displays a display image based on pixel signals obtained from the CCU 5039 .
- the display device 5041 may function as an input device that enables line-of-sight recognition, voice recognition, and gesture-based instruction input by being equipped with a camera and a microphone.
- the output device 5055 is a device for outputting information acquired from the CCU 5039, such as a printer.
- the output device 5055 prints on paper a print image based on the pixel signals acquired from the CCU 5039, for example.
- the support device 5027 is an articulated arm including a base portion 5029 having an arm control device 5045 , an arm portion 5031 extending from the base portion 5029 , and a holding portion 5032 attached to the tip of the arm portion 5031 .
- the arm control device 5045 is configured by a processor such as a CPU, and operates according to a predetermined program to control driving of the arm section 5031 .
- the support device 5027 controls parameters such as the length of each link 5035 constituting the arm portion 5031 and the rotation angle and torque of each joint 5033 by means of the arm control device 5045 .
- the support device 5027 functions as an endoscope support arm that supports the endoscope 5001 during surgery. Thereby, the support device 5027 can take the place of the scopist who is an assistant holding the endoscope 5001 .
- the support device 5027 may be a device that supports a microscope device 5301, which will be described later, and can also be called a medical support arm.
- the control of the support device 5027 may be an autonomous control method by the arm control device 5045, or may be a control method in which the arm control device 5045 controls based on the user's input.
- control method is a master/slave method in which the support device 5027 as a slave device (replica device), which is a patient cart, is controlled based on the movement of the master device (primary device), which is the operator console at hand of the user. It's okay. Also, the control of the support device 5027 may be remotely controlled from outside the operating room.
- slave device replica device
- master device primary device
- control of the support device 5027 may be remotely controlled from outside the operating room.
- FIG. 22 is a diagram illustrating an example of a schematic configuration of a microsurgery system to which technology according to the present disclosure can be applied;
- the same reference numerals are given to the same configurations as those of the endoscope system 5000, and duplicate descriptions thereof will be omitted.
- FIG. 22 schematically shows an operator 5067 performing an operation on a patient 5071 on a patient bed 5069 using a microsurgery system 5300 .
- FIG. 22 omits illustration of the cart 5037 in the configuration of the microsurgery system 5300, and also shows a simplified microscope device 5301 instead of the endoscope 5001.
- the microscope device 5301 in this description may refer to the microscope section 5303 provided at the tip of the link 5035 or may refer to the entire configuration including the microscope section 5303 and the support device 5027 .
- an image of a surgical site captured by a microscope device 5301 is enlarged and displayed on a display device 5041 installed in the operating room.
- the display device 5041 is installed at a position facing the operator 5067, and the operator 5067 observes the state of the operation site by the image displayed on the display device 5041, for example, resection of the affected area.
- Various measures are taken against Microsurgery systems are used, for example, in ophthalmic and brain surgery.
- the support device 5027 can support other observation devices or other surgical tools instead of the endoscope 5001 or the microscope section 5303 at its distal end.
- the other observation device for example, forceps, forceps, a pneumoperitoneum tube for pneumoperitoneum, or an energy treatment instrument for incising tissue or sealing a blood vessel by cauterization can be applied.
- the technology according to the present disclosure may be applied to a support device that supports components other than such a microscope section.
- the technology according to the present disclosure can be suitably applied to the surgical instrument 5021 among the configurations described above. Specifically, by irradiating the affected area of the patient with a short laser pulse from the laser device 1 according to the present embodiment, the affected area can be treated more safely and reliably without damaging the area around the affected area. can.
- this technique can take the following structures. (1) a laminated semiconductor layer having a first reflective layer for a first wavelength and an active layer for performing surface emission of the first wavelength; A second reflective layer for a second wavelength on a first surface facing the laminated semiconductor layer disposed on the rear side of the optical axis of the laminated semiconductor layer, and a second reflective layer for the first wavelength on a second surface opposite to the first surface.
- a laser medium having a third reflective layer for a fourth reflective layer for the second wavelength, disposed on the second surface or disposed on the rear side of the optical axis from the second surface; a first resonator that resonates the light of the first wavelength between the first reflective layer and the third reflective layer; a second resonator that resonates the light of the second wavelength between the second reflective layer and the fourth reflective layer; a heat exhaust unit disposed between the laminated semiconductor layer and the laser medium for exhausting heat generated by at least one of the laminated semiconductor layer and the laser medium;
- the laser device wherein the optical axis of the laminated semiconductor layer and the optical axis of the laser medium are arranged on one axis.
- the heat exhaust section includes a first member disposed between the laminated semiconductor layer and the laser medium and having a higher thermal conductivity than the laser medium.
- the heat exhaust section includes a first member disposed between the laminated semiconductor layer and the laser medium and having a higher thermal conductivity than the laser medium.
- (3) comprising a metal layer disposed on part or all of the surface of the first member facing the laser medium and having higher thermal conductivity than the laminated semiconductor layer and the laser medium; Laser device as described.
- (4) comprising a second member that is bonded to the side surface of the laminated semiconductor layer, the side surface of the first member, and the side surface of the laser medium and that dissipates heat transferred to the first member; 3) The laser device described in 3).
- the first member includes at least one of sapphire and diamond;
- a protective layer disposed on the surface of the first member facing the laminated semiconductor layer, transmitting the light of the first wavelength and reflecting the light of the second wavelength; The laser device according to any one of (6) to (6).
- the first member has a first region that transmits the light of the first wavelength, and a second region that is arranged around the first region and has a higher thermal conductivity than the laser medium, ( The laser device according to any one of 1) to (7). (9) The laser device according to (8), wherein the second region is an insulating material or a metal material. (10) the second region is arranged to surround the first region; The laser device according to (8) or (9), wherein the outer peripheral surface of the second region or the corners of the outer peripheral surface are positioned equidistant from the center position of the first region.
- a plurality of the first resonators and a plurality of the second resonators are provided in the plane direction of the laminated semiconductor layer, the heat removal section, and the laser medium.
- (17) comprising a polarization control element arranged between the laser medium and the saturable absorber or on the rear side of the optical axis relative to the saturable absorber for controlling the polarization state of the light of the second wavelength;
- the fourth reflective layer is an output coupling mirror in the second resonator.
- the laminated semiconductor layer has a fifth reflective layer arranged closer to the laser medium than the first reflective layer, and a fifth reflective layer for the first wavelength; 2.
- said fifth reflective layer transmits part of the light of said first wavelength.
- the laser element is a laminated semiconductor layer having a first reflective layer for a first wavelength and an active layer for surface emission of the first wavelength; A second reflective layer for a second wavelength on a first surface facing the laminated semiconductor layer disposed on the rear side of the optical axis of the laminated semiconductor layer, and a second reflective layer for the first wavelength on a second surface opposite to the first surface.
- a laser medium having a third reflective layer for a fourth reflective layer for the second wavelength, disposed on the second surface or disposed on the rear side of the optical axis from the second surface; a first resonator that resonates the light of the first wavelength between the first reflective layer and the third reflective layer; a second resonator that resonates the light of the second wavelength between the second reflective layer and the fourth reflective layer; a heat exhaust unit disposed between the laminated semiconductor layer and the laser medium for exhausting heat generated by at least one of the laminated semiconductor layer and the laser medium;
- An electronic device wherein an optical axis of the laminated semiconductor layer and an optical axis of the laser medium are arranged on one axis.
- the laser amplifying element wherein the optical axis of the laminated semiconductor layer and the optical axis of the laser medium are arranged on one axis.
- the light of the second wavelength is incident from the optical input section to cause the amplification medium to generate the The laser amplifying device according to (21), wherein the light of the second wavelength is amplified and output from the light output unit after the light of the second wavelength is reciprocated a plurality of times.
- a first heat exhaust member disposed between the laminated semiconductor layer and the laser medium for discharging heat generated by at least one of the laminated semiconductor layer and the laser medium;
- the first heat exhaust member has a plurality of via members that penetrate the first heat exhaust member and are joined to the laminated semiconductor and the laser medium,
- the laser amplifying device according to any one of (23) to (27), wherein thermal conductivity of the plurality of via members is higher than thermal conductivity of the first heat exhaust member.
- the laser according to any one of (21) to (28), wherein the first reflecting member and the second reflecting member are convex mirror members that reflect incident light so as not to be condensed. amplification element.
- the first reflecting member and the second reflecting member are multilayer films formed by laminating at least one of a semiconductor material, a metal material, and a dielectric material, which are arranged on the first side surface and the second side surface.
- the laser amplification device according to any one of (21) to (29), wherein
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Abstract
Description
前記積層半導体層の光軸の後方側に配置され、前記積層半導体層と対向する第1面に第2波長に対する第2反射層および前記第1面と反対側の第2面に前記第1波長に対する第3反射層を有するレーザ媒質と、
前記第2面に配置されるか、又は前記第2面より光軸の後方側に配置される、前記第2波長に対する第4反射層と、
前記第1反射層および前記第3反射層の間で前記第1波長の光を共振させる第1共振器と、
前記第2反射層および前記第4反射層の間で前記第2波長の光を共振させる第2共振器と、
前記積層半導体層と前記レーザ媒質との間に配置され、前記積層半導体層及び前記レーザ媒質の少なくとも一方で発生された熱を排熱する排熱部と、を備え、
前記積層半導体層の光軸及び前記レーザ媒質の光軸は、一軸上に配置される、レーザ素子が提供される。
前記基板上のパッドと前記積層半導体層の電極とに接続されるボンディングワイヤと、を備え、
前記第2部材は、前記積層半導体層及び前記レーザ媒質の側面と、前記ボンディングワイヤとを覆うように配置されてもよい。
前記第2部材は、金属材料を含んでもよい。
前記第2領域の外周面又は前記外周面の角部は、前記第1領域の中心位置から等距離に位置してもよい。
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記可飽和吸収体の光軸は、一軸上に配置されてもよい。
前記第5反射層は、前記第1波長の光の一部を透過させてもよい。
前記レーザ素子から光を放出する制御を行う制御部と、を備える電子機器であって、
前記レーザ素子は、
第1波長に対する第1反射層と、前記第1波長の面発光を行う活性層と、を有する積層半導体層と、
前記積層半導体層の光軸の後方側に配置され、前記積層半導体層と対向する第1面に第2波長に対する第2反射層および前記第1面と反対側の第2面に前記第1波長に対する第3反射層を有するレーザ媒質と、
前記第2面に配置されるか、又は前記第2面より光軸の後方側に配置される、前記第2波長に対する第4反射層と、
前記第1反射層および前記第3反射層の間で前記第1波長の光を共振させる第1共振器と、
前記第2反射層および前記第4反射層の間で前記第2波長の光を共振させる第2共振器と、
前記積層半導体層と前記レーザ媒質との間に配置され、前記積層半導体層及び前記レーザ媒質の少なくとも一方で発生された熱を排熱する排熱部と、を備え、
前記積層半導体層の光軸及び前記レーザ媒質の光軸は、一軸上に配置される、電子機器が提供される。
まず、本開示によるレーザ素子の内部構成と動作を説明する前に、本開示によるレーザ素子の技術的特徴を説明する。
(1)第1共振器と第2共振器が、固体レーザ媒質を共有する。第1共振器は、励起光源と固体レーザ媒質とを含む。第2共振器は、固体レーザ媒質と可飽和吸収体を含んでおり、第1共振器からの励起光によってQスイッチレーザ発振を行う。
本開示によるレーザ素子では、励起光源に電流を注入することによって発生される励起光を、第1共振器内の固体レーザ媒質で吸収させる。固体レーザ媒質は、第1共振器に隣接して設置された可飽和吸収体とともに、第2共振器を構成する。固体レーザ媒質が十分な励起状態となり、自然放出光の出力が上がって、ある閾値を超えると可飽和吸収体での光吸収率が急激に低下し、固体レーザ媒質で発生された自然放出光は可飽和吸収体を透過できるようになり、固体レーザ媒質において誘導放出を生じさせる。これによりQスイッチパルス発振が起こる。
以下、本開示によるレーザ素子の具体的な実施形態を説明する。図1は本開示によるレーザ素子1の基本構成を示す図である。図1のレーザ素子1は、励起光源2と、固体レーザ媒質3と、可飽和吸収体4とを一体に接合した構成を備えている。
次に、図1のレーザ素子1の動作を説明する。励起光源2の電極を介して電流を活性層7に注入することで、第1共振器11内で第1波長λ1のレーザ発振が起こり、固体レーザ媒質3が励起される。固体レーザ媒質3には可飽和吸収体4が接合されていることから、第1波長λ1のレーザ発振が起こった最初の段階では、固体レーザ媒質3からの自然放出光は可飽和吸収体4に吸収されてしまい、可飽和吸収体4の出射面側の第4反射層R4による光フィードバックが起こらず、Qスイッチレーザ発振には至らない。
積層半導体層からなる励起光源2と固体レーザ媒質3とを隣接して、又は直接接合したときに、励起光源2の活性層7に流す電流を増やすほど励起光源の温度が上昇し、励起光源2から固体レーザ媒質3に伝熱されて固体レーザ媒質3の温度が高くなる。これにより、固体レーザ媒質3での第1波長から第2波長への光波長の変換効率が低下する。一方、励起光吸収によって固体レーザ媒質3の温度が上昇すると、固体レーザ媒質3から励起光源2に伝熱されて、励起光源2の温度がさらに上昇する。これにより、励起光源2と固体レーザ媒質3との熱的干渉が生じ、励起光源2のI-L特性(発光効率)が悪化するとともに、活性層7のジャンクション温度Tjが上昇し、長期信頼性(MTTF:Mean Time To Failure)が悪化する。
本開示によるレーザ素子では、積層半導体層からなる励起光源2と固体レーザ媒質3との間に排熱部を配置するため、小型一体化構造の利点を失うことなく、熱的干渉によるレーザ光の発振効率の低下や光波長の変換効率の低下を防止できる。
図2は第1形態による排熱部13を備えたレーザ素子1の模式的な断面図である。図2のレーザ素子1はサブマウント基板91の上に載置され、サブマウント基板91は支持基板92の上に載置されている。レーザ素子1は、積層半導体層からなる励起光源2と、排熱部13と、固体レーザ媒質3と、冷却部材(第2部材)14とを備えている。
図3は第2形態による排熱部13を備えたレーザ素子1の模式的な断面図である。図3のレーザ素子1は、図2のレーザ素子1に可飽和吸収体4を追加したものである。図3に示すように、可飽和吸収体4は、固体レーザ媒質3の端面に接合される。図3のレーザ素子1における第2共振器12は、図1と同様に、固体レーザ媒質3内の第2反射層R2と可飽和吸収体4内の第4反射層R4との間で、第2波長λ2の光を共振させる。
図4は第3形態による排熱部13を備えたレーザ素子1の模式的な断面図である。図4のレーザ素子1は、排熱部13が二層構造になっており、サファイア等の排熱部材17の表面に、Cuなどの熱伝導率の高い金属層18を配置している。金属層18は、排熱部材17の上に、例えば蒸着やスパッタなどにより形成される。冷却部材14、排熱部13、及び固体レーザ媒質3の側面には冷却部材14が接合されているため、排熱部材17の表面に金属層18を配置することで、固体レーザ媒質3からの熱を、金属層18を介して排熱部材17と冷却部材14により効率よく伝熱でき、排熱部13の排熱性能がより向上する。ただし、第1波長の光が金属層に吸収すると発熱するため、第1波長の光路は避ける必要がある。
図5は第4形態による排熱部13を備えたレーザ素子1の模式的な断面図である。図5のレーザ素子1は、排熱部13の構造が第1~第3形態とは異なる。図5の排熱部13は、第1領域13aと第2領域13bとを有する。第1領域13aは、光軸を含む領域であり、排熱部13の略中央に配置されている。第1領域13aは、第1波長の光を透過させる領域である。第1領域13aは、第1波長の光を透過させる透明材料層でもよいし、単なるエアギャップでもよい。第2領域13bは、第1領域13aの周囲に配置され、固体レーザ媒質3よりも熱伝導率の高い領域である。第2領域13bは、複数のビアとして配置されてもよい。第1領域13aがエアギャップの場合、第2領域13bは、第1領域13aのエアギャップを支持するためのスペーサ部材として機能する。第2領域13bは、絶縁材料又は金属材料であり、例えば、サファイアやダイヤモンドなどの熱伝導率の高い材料で形成される。
図6は第5形態による排熱部13を備えたレーザ素子1の模式的な断面図である。図2~図5のレーザ素子1では、ボンディングワイヤ16にてレーザ素子1の活性層7への電流注入を行っている。ボンディングワイヤ16は、切断を防止するために、保護層で覆うのが一般的である。図6のレーザ素子1では、ボンディングワイヤ16の保護層と冷却部材14を一体化するものである。以下では、この一体化した部材を冷却部材14と呼ぶことにする。図6の冷却部材14は、励起光源2、排熱部材17及び固体レーザ媒質3の側面に接するだけでなく、ボンディングワイヤ16を覆うように配置されている。図6のボンディングワイヤ16の保護層は絶縁材料で被覆されていることが望ましい。絶縁被覆材料には、樹脂材やガラス材料などが知られており、絶縁材料であれば、特定の材料には限定されない。冷却部材14の熱伝導率は固体レーザ媒質3よりも高い材料であればよく、特定の材料には限定されない。
図7は第6形態による排熱部13を備えたレーザ素子1の模式的な断面図である。図7のレーザ素子1は、排熱部13の層構成が図2や図4の排熱部13とは異なっている。図7の排熱部13は、積層半導体層2に対向する側の表面に積層される保護層19を有する。保護層19は、第1波長λ1を透過させ第2波長λ2の光を反射させる層として機能する。
(排熱部13の第7形態)
図8は第7形態による排熱部13を備えたレーザ素子1の模式的な断面図である。本開示によるレーザ素子1内の固体レーザ媒質3で吸収された励起光のエネルギーの一部は熱に変換され、固体レーザ媒質3の温度が上昇する。その際、固体レーザ媒質3内に温度分布が生じ、その温度分布に伴う屈折率分布が生じる。無機材料からなる多くの固体レーザ媒質3は一般に、温度が高いほど屈折率が高くなり、周辺部分は屈折率が徐々に低くなる。これにより、固体レーザ媒質3中には、熱レンズと呼ばれる仮想的な集光レンズが形成される。この熱レンズ効果により、第2共振器12の内部でレーザ光が集光される。第2共振器12の内部では、短パルス化によってレーザ光のピーク強度が高くなっている状態のため、熱レンズ効果によるレーザ光の集光により、第1共振器と第2共振器12内部での光損傷がより顕著に起きやすくなる。特に第1共振器を構成する積層半導体層は、バンドギャップが小さい材料で構成されているため、第2共振器12で発生される第2波長λ2のレーザ光の漏れ光が、第1共振器に入り込むと、多光子吸収に起因する光損傷が発生しやすくなる。
図9は第8形態に係る排熱部13を備えたレーザ素子1の模式的な断面図である。図9のレーザ素子1における排熱部13は、積極的な冷却機能を有する排熱部材17を有する。例えば、排熱部材17は、冷媒17aを収納及び循環させる機能を備えており、具体的な実装例として、励起光光軸部分は透明部材とし、その周囲に冷媒を収納したヒートパイプ17bを設ける形態が考えられる。また、排熱部材17にヒートパイプ17bではなくレーザ素子外に通じる微細流路を設け冷媒17aを循環させる形態も考えられる。冷媒17aにより強制的に冷却することで効率よくレーザ媒質3の排熱を行うことができる。冷媒17aは液体でもよいし、気体でもよい。
図10は第9形態に係る排熱部13を備えたレーザ素子1の模式的な断面図である。図10のレーザ素子1は、排熱部13に加えて、光制御部材(偏光制御素子)43を備えている。光制御部材43は、例えば固体レーザ媒質3と可飽和吸収体4の間、又は可飽和吸収体4よりも光軸後方側に配置される。光制御部材43は、第2波長λ2の光の屈折、回折又は偏光方向を制御する。より具体的には、光制御部材43は、例えばフォトニック結晶層である。フォトニック結晶層は、屈折率が周期的に変化する層である。また、フォトニック結晶層にて、P偏光とS偏光のいずれか一方を選択することができる。また、光制御部材43は、回折格子でもよい。
図11A、図11B、図11C、及び図11Dは第10形態に係る排熱部13の平面形状を模式的に示す図である。図11A~図11Cに示す排熱部13は、上述した第1形態~第8形態のいずれかによる排熱部13を基本構造として備えており、その基本構造に追加の技術的特徴を付加したものである。図11A~図11Cに示す排熱部13は、平面形状が多角形の冷却部材14の中心位置にレーザ光の光軸を配置している。レーザ光の光軸の周囲には、サファイア等の排熱部材17が配置されていてもよいし、エアギャップでもよい。レーザ光の光軸の部分が最も温度が高くなるため、その周囲に配置される排熱部材17に均等に伝熱される構造が望ましい。そこで、図11A~図11Cでは、冷却部材14の平面形状を正n角形(nは3以上の整数)とし、正n角形の中心位置をレーザ素子1の光軸としている。また、図11Dに示す排熱部13は、平面形状が円形の冷却部材14の中心位置にレーザ光の光軸をお配置している。これにより、正n角形又は円形の各頂点から光軸までの距離が等しくなり、排熱部13の全域に均等に熱が伝わって、冷却部材14で放熱することができる。
図12は複数のレンズ素子を一次元方向又は二次元方向に配置したレーザアレイ44の模式的な断面図である。図12では、各レンズ素子が図2と同様の構造の排熱部13を有する例を示しているが、第2~第10形態のいずれかによる排熱部13を有していてもよい。複数のレンズ素子が有する排熱部13は、一体に接合されている。一体構造の排熱部13は、排熱部材17を有する。複数のレンズ素子を有するレンズアレイの側面には冷却部材14が接合されている。冷却部材14は、排熱部材17に接合されている。これにより、各レンズ素子内の励起光源2と固体レンズ媒体で生じた熱は排熱部材17に伝熱され、排熱部材17から冷却部材14に放熱される。
図13A、図13B、図13C、及び図13Dは、排熱部13を設けた場合と設けない場合の、レーザアレイ44の中央部と角部のレーザ光源の温度分布を示す図である。図13Aと図13Bは、レーザアレイ44の中央部のレーザ光源の温度分布を示しており、図13Aは排熱部13を備えていない場合、図13Bは排熱部13を備えている場合を示している。また、図13Cと図13Dは、レーザアレイ44の角部のレーザ光源の温度分布を示しており、図13Cは排熱部13を備えていない場合、図13Dは排熱部13を備えている場合を示している。
また、第2共振器12がQスイッチにより第2波長λ2のレーザパルスを放出する際に、高ピーク強度の第2波長λ2の発振光が戻り光として励起光源2に入り込むおそれがある。励起光源2はバンドキャップの小さい半導体材料で形成されているため、戻り光により破壊されるおそれがある。このため、励起光源2と固体レーザ媒質3との間には、共振器長を短くしつつも、排熱部13と保護層19である短波長透過フィルタ膜(SWPF)を複数配置して、戻り光が励起光源2に入り込まないようにするのが望ましい。
図14は本開示のレーザ素子1の製造工程を模式的に示す図である。図14は、図8で示した光損傷回避のための光学素子41と可飽和吸収体4とを備えたレーザ素子1の製造工程を示している。また、図14では、可飽和吸収体の上面側に光学素子41用の凸面ミラー42を形成する例を示している。
上述したように、本開示のレーザ素子1では、励起光源2と固体レーザ媒質3の間に排熱部13を設けるため、励起光源2と固体レーザ媒質3の少なくとも一方で発生された熱を排熱することができる。特に、排熱部13として、サファイアやダイヤモンド等の固体レーザ媒質3よりも熱伝導率の高い材料の排熱部材17を用いることで、励起光源2と固体レーザ媒質3で発生された熱を効率よく排熱することができる。また、励起光源2、排熱部13、及び固体レーザ媒質3の側面に、Cu等の冷却部材14を接合することで、励起光源2と固体レーザ媒質3で発生された熱を、排熱部材17を介して冷却部材14に放熱させることができ、レーザ素子1内の温度上昇を抑制できる。
図1では、レーザ素子1が可飽和吸収体4を備えており、短パルスのパルスレーザ光を放出する例を示したが、可飽和吸収体4を持たずにCWレーザ光を放出するレーザ素子1においても、励起光源2と固体レーザ媒体との間で熱的な干渉が生じるおそれがある。
上述した本開示によるレーザ素子1の構造をレーザ増幅素子に適用することができる。従来、短パルスレーザ光の増幅は、光損傷を回避するために、増幅光のピーク強度を下げて増幅する手法が考案されて実施されている。例えば、レーザ光のパルス幅を一旦広げてその状態で増幅を行った後に、パルス幅を圧縮するチャープパルス増幅法や、レーザ光のビームを空間的に拡げてピーク強度を下げるthin disk型方式やslab型方式などがある。しかし、これらの方式はいずれも、巨大且つ複雑な光学系を必要とするため、小型化が困難で、高コストである。
本開示に係る技術は、医療イメージングシステム(以下では、電子機器とも呼ぶ)、LiDAR(Light Detection And Ranging)装置などの測距システム、レーザ加工装置用の光源などに幅広く適用することができる。医療イメージングシステムは、イメージング技術を用いた医療システムであり、例えば、内視鏡システムや顕微鏡システムである。
内視鏡システムの例を図20、図21を用いて説明する。図20は、本開示に係る技術が適用可能な内視鏡システム5000の概略的な構成の一例を示す図である。図21は、内視鏡5001およびCCU(Camera Control Unit)5039の構成の一例を示す図である。図20では、手術参加者である術者(例えば、医師)5067が、内視鏡システム5000を用いて、患者ベッド5069上の患者5071に手術を行っている様子が図示されている。図20に示すように、内視鏡システム5000は、医療イメージング装置である内視鏡5001と、CCU5039と、光源装置5043と、記録装置5053と、出力装置5055と、内視鏡5001を支持する支持装置5027と、から構成される。
内視鏡5001は、患者5071の体内を撮像する撮像部であり、例えば、図21に示すように、入射した光を集光する集光光学系50051と、撮像部の焦点距離を変更して光学ズームを可能とするズーム光学系50052と、撮像部の焦点距離を変更してフォーカス調整を可能とするフォーカス光学系50053と、受光素子50054と、を含むカメラ5005である。内視鏡5001は、接続されたスコープ5003を介して光を受光素子50054に集光することで画素信号を生成し、CCU5039に伝送系を通じて画素信号を出力する。なお、スコープ5003は、対物レンズを先端に有し、接続された光源装置5043からの光を患者5071の体内に導光する挿入部である。スコープ5003は、例えば硬性鏡では硬性スコープ、軟性鏡では軟性スコープである。スコープ5003は直視鏡や斜視鏡であってもよい。また、画素信号は画素から出力された信号に基づいた信号であればよく、例えば、RAW信号や画像信号である。また、内視鏡5001とCCU5039とを接続する伝送系にメモリを搭載し、メモリに内視鏡5001やCCU5039に関するパラメータを記憶する構成にしてもよい。メモリは、例えば、伝送系の接続部分やケーブル上に配置されてもよい。例えば、内視鏡5001の出荷時のパラメータや通電時に変化したパラメータを伝送系のメモリに記憶し、メモリから読みだしたパラメータに基づいて内視鏡の動作を変更してもよい。また、内視鏡と伝送系をセットにして内視鏡と称してもよい。受光素子50054は、受光した光を画素信号に変換するセンサであり、例えばCMOS(Complementary Metal Oxide Semiconductor)タイプの撮像素子である。受光素子50054は、Bayer配列を有するカラー撮影可能な撮像素子であることが好ましい。また、受光素子50054は、例えば4K(水平画素数3840×垂直画素数2160)、8K(水平画素数7680×垂直画素数4320)または正方形4K(水平画素数3840以上×垂直画素数3840以上)の解像度に対応した画素数を有する撮像素子であることが好ましい。受光素子50054は、1枚のセンサチップであってもよいし、複数のセンサチップでもよい。例えば、入射光を所定の波長帯域ごとに分離するプリズムを設けて、各波長帯域を異なる受光素子で撮像する構成であってもよい。また、立体視のために受光素子を複数設けてもよい。また、受光素子50054は、チップ構造の中に画像処理用の演算処理回路を含んでいるセンサであってもよいし、ToF(Time of Flight)用センサであってもよい。なお、伝送系は例えば光ファイバケーブルや無線伝送である。無線伝送は、内視鏡5001で生成された画素信号が伝送可能であればよく、例えば、内視鏡5001とCCU5039が無線接続されてもよいし、手術室内の基地局を経由して内視鏡5001とCCU5039が接続されてもよい。このとき、内視鏡5001は画素信号だけでなく、画素信号に関連する情報(例えば、画素信号の処理優先度や同期信号等)を同時に送信してもよい。なお、内視鏡はスコープとカメラを一体化してもよく、スコープの先端部に受光素子を設ける構成としてもよい。
CCU5039は、接続された内視鏡5001や光源装置5043を統括的に制御する制御装置であり、例えば、図21に示すように、FPGA50391、CPU50392、RAM50393、ROM50394、GPU50395、I/F50396を有する情報処理装置である。また、CCU5039は、接続された表示装置5041や記録装置5053、出力装置5055を統括的に制御してもよい。例えば、CCU5039は、光源装置5043の照射タイミングや照射強度、照射光源の種類を制御する。また、CCU5039は、内視鏡5001から出力された画素信号に対して現像処理(例えばデモザイク処理)や補正処理といった画像処理を行い、表示装置5041等の外部装置に処理後の画素信号(例えば画像)を出力する。また、CCU5039は、内視鏡5001に対して制御信号を送信し、内視鏡5001の駆動を制御する。制御信号は、例えば、撮像部の倍率や焦点距離などの撮像条件に関する情報である。なお、CCU5039は画像のダウンコンバート機能を有し、表示装置5041に高解像度(例えば4K)の画像を、記録装置5053に低解像度(例えばHD)の画像を同時に出力可能な構成としてもよい。
光源装置5043は、所定の波長帯域の光を照射可能な装置であり、例えば、複数の光源と、複数の光源の光を導光する光源光学系と、を備える。光源は、例えばキセノンランプ、LED光源やLD光源である。光源装置5043は、例えば三原色R、G、Bのそれぞれに対応するLED光源を有し、各光源の出力強度や出力タイミングを制御することで白色光を出射する。また、光源装置5043は、通常光観察に用いられる通常光を照射する光源とは別に、特殊光観察に用いられる特殊光を照射可能な光源を有していてもよい。特殊光は、通常光観察用の光である通常光とは異なる所定の波長帯域の光であり、例えば、近赤外光(波長が760nm以上の光)や赤外光、青色光、紫外光である。通常光は、例えば白色光や緑色光である。特殊光観察の一種である狭帯域光観察では、青色光と緑色光を交互に照射することにより、体組織における光の吸収の波長依存性を利用して、粘膜表層の血管等の所定の組織を高コントラストで撮影することができる。また、特殊光観察の一種である蛍光観察では、体組織に注入された薬剤を励起する励起光を照射し、体組織または標識である薬剤が発する蛍光を受光して蛍光画像を得ることで、通常光では術者が視認しづらい体組織等を、術者が視認しやすくすることができる。例えば、赤外光を用いる蛍光観察では、体組織に注入されたインドシアニングリーン(ICG)等の薬剤に励起波長帯域を有する赤外光を照射し、薬剤の蛍光を受光することで、体組織の構造や患部を視認しやすくすることができる。また、蛍光観察では、青色波長帯域の特殊光で励起され、赤色波長帯域の蛍光を発する薬剤(例えば5-ALA)を用いてもよい。なお、光源装置5043は、CCU5039の制御により照射光の種類を設定される。CCU5039は、光源装置5043と内視鏡5001を制御することにより、通常光観察と特殊光観察が交互に行われるモードを有してもよい。このとき、通常光観察で得られた画素信号に特殊光観察で得られた画素信号に基づく情報を重畳されることが好ましい。また、特殊光観察は、赤外光を照射して臓器表面より奥を見る赤外光観察や、ハイパースペクトル分光を活用したマルチスペクトル観察であってもよい。さらに、光線力学療法を組み合わせてもよい。
記録装置5053は、CCU5039から取得した画素信号(例えば画像)を記録する装置であり、例えばレコーダーである。記録装置5053は、CCU5039から取得した画像をHDDやSDD、光ディスクに記録する。記録装置5053は、病院内のネットワークに接続され、手術室外の機器からアクセス可能にしてもよい。また、記録装置5053は画像のダウンコンバート機能またはアップコンバート機能を有していてもよい。
表示装置5041は、画像を表示可能な装置であり、例えば表示モニタである。表示装置5041は、CCU5039から取得した画素信号に基づく表示画像を表示する。なお、表示装置5041はカメラやマイクを備えることで、視線認識や音声認識、ジェスチャによる指示入力を可能にする入力デバイスとしても機能してよい。
出力装置5055は、CCU5039から取得した情報を出力する装置であり、例えばプリンタである。出力装置5055は、例えば、CCU5039から取得した画素信号に基づく印刷画像を紙に印刷する。
支持装置5027は、アーム制御装置5045を有するベース部5029と、ベース部5029から延伸するアーム部5031と、アーム部5031の先端に取り付けられた保持部5032とを備える多関節アームである。アーム制御装置5045は、CPU等のプロセッサによって構成され、所定のプログラムに従って動作することにより、アーム部5031の駆動を制御する。支持装置5027は、アーム制御装置5045によってアーム部5031を構成する各リンク5035の長さや各関節5033の回転角やトルク等のパラメータを制御することで、例えば保持部5032が保持する内視鏡5001の位置や姿勢を制御する。これにより、内視鏡5001を所望の位置または姿勢に変更し、スコープ5003を患者5071に挿入でき、また、体内での観察領域を変更できる。支持装置5027は、術中に内視鏡5001を支持する内視鏡支持アームとして機能する。これにより、支持装置5027は、内視鏡5001を持つ助手であるスコピストの代わりを担うことができる。また、支持装置5027は、後述する顕微鏡装置5301を支持する装置であってもよく、医療用支持アームと呼ぶこともできる。なお、支持装置5027の制御は、アーム制御装置5045による自律制御方式であってもよいし、ユーザの入力に基づいてアーム制御装置5045が制御する制御方式であってもよい。例えば、制御方式は、ユーザの手元の術者コンソールであるマスター装置(プライマリ装置)の動きに基づいて、患者カートであるスレイブ装置(レプリカ装置)としての支持装置5027が制御されるマスタ・スレイブ方式でもよい。また、支持装置5027の制御は、手術室の外から遠隔制御が可能であってもよい。
図22は、本開示に係る技術が適用され得る顕微鏡手術システムの概略的な構成の一例を示す図である。なお、以下の説明において、内視鏡システム5000と同様の構成については、同一の符号を付し、その重複する説明を省略する。
(1)第1波長に対する第1反射層と、前記第1波長の面発光を行う活性層と、を有する積層半導体層と、
前記積層半導体層の光軸の後方側に配置され、前記積層半導体層と対向する第1面に第2波長に対する第2反射層および前記第1面と反対側の第2面に前記第1波長に対する第3反射層を有するレーザ媒質と、
前記第2面に配置されるか、又は前記第2面より光軸の後方側に配置される、前記第2波長に対する第4反射層と、
前記第1反射層および前記第3反射層の間で前記第1波長の光を共振させる第1共振器と、
前記第2反射層および前記第4反射層の間で前記第2波長の光を共振させる第2共振器と、
前記積層半導体層と前記レーザ媒質との間に配置され、前記積層半導体層及び前記レーザ媒質の少なくとも一方で発生された熱を排熱する排熱部と、を備え、
前記積層半導体層の光軸及び前記レーザ媒質の光軸は、一軸上に配置される、レーザ素子。
(2)前記排熱部は、前記積層半導体層と前記レーザ媒質との間に配置され、前記レーザ媒質よりも熱伝導率が高い第1部材を有する、(1)に記載のレーザ素子。
(3)前記レーザ媒質に対向する側の前記第1部材の表面の一部またはすべてに配置され、前記積層半導体層及び前記レーザ媒質よりも熱伝導率の高い金属層を備える、(2)に記載のレーザ素子。
(4)前記積層半導体層の側面、前記第1部材の側面、及び前記レーザ媒質の側面に接合され、前記第1部材に伝達された熱を放熱する第2部材を備える、(2)又は(3)に記載のレーザ素子。
(5)前記積層半導体層を支持する基板と、
前記基板上のパッドと前記積層半導体層の電極とに接続されるボンディングワイヤと、を備え、
前記第2部材は、前記積層半導体層及び前記レーザ媒質の側面と、前記ボンディングワイヤとを覆うように配置される、(4)に記載のレーザ素子。
(6)前記第1部材は、サファイア及びダイヤモンドの少なくとも一方を含み、
前記第2部材は、金属材料を含む、(4)又は(5)に記載のレーザ素子。
(7)前記積層半導体層に対向する側の前記第1部材の表面に配置され、前記第1波長の光を透過させ、かつ前記第2波長の光を反射させる保護層を備える、(2)乃至(6)のいずれか一項に記載のレーザ素子。
(8)前記第1部材は、前記第1波長の光を透過させる第1領域と、前記第1領域の周囲に配置され前記レーザ媒質より熱伝導率の高い第2領域と、を有する、(1)乃至(7)のいずれか一項に記載のレーザ素子。
(9)前記第2領域は、絶縁材料又は金属材料である、(8)に記載のレーザ素子。
(10)前記第2領域は、前記第1領域を取り囲むように配置され、
前記第2領域の外周面又は前記外周面の角部は、前記第1領域の中心位置から等距離に位置する、(8)又は(9)に記載のレーザ素子。
(11)前記積層半導体層、前記排熱部、及びレーザ媒質の面方向に、複数の前記第1共振器と複数の前記第2共振器とを備える、
(1)乃至(10)のいずれか一項に記載のレーザ素子。
(12)前記排熱部は、前記積層半導体層と前記レーザ媒質との間に配置されるエアギャップを有する、(1)に記載のレーザ素子。
(13)前記第2反射層から前記第4反射層の間に配置され、前記第2波長の光のビーム径を拡大させる第1光学素子を備える、(1)乃至(12)のいずれか一項に記載のレーザ素子。
(14)前記第1共振器は、前記第1波長の光を光軸方向に集光させる第2光学素子を有する、(1)乃至(13)のいずれか一項に記載のレーザ素子。
(15)前記レーザ媒質と反対側の第3面に前記第4反射層を有する可飽和吸収体を備え、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記可飽和吸収体の光軸は、一軸上に配置される、(1)乃至(14)のいずれか一項に記載のレーザ素子。
(16)前記積層半導体層、前記レーザ媒質、および前記可飽和吸収体は一体に接合されている、(15)に記載のレーザ素子。
(17)前記レーザ媒質と前記可飽和吸収体との間、又は前記可飽和吸収体よりも光軸後方側に配置され、前記第2波長の光の偏光状態を制御する偏光制御素子を備える、(15)又は(16)に記載のレーザ素子。
(18)前記第4反射層は、前記第2共振器における出力結合鏡である、請求項1に記載のレーザ素子。
(19)前記積層半導体層は、前記第1反射層よりも前記レーザ媒質に近い側に配置され、前記第1波長に対する第5反射層を有し、
前記第5反射層は、前記第1波長の光の一部を透過させる、請求項1に記載のレーザ素子。
(20)レーザ素子と、
前記レーザ素子から光を放出する制御を行う制御部と、を備える電子機器であって、
前記レーザ素子は、
第1波長に対する第1反射層と、前記第1波長の面発光を行う活性層と、を有する積層半導体層と、
前記積層半導体層の光軸の後方側に配置され、前記積層半導体層と対向する第1面に第2波長に対する第2反射層および前記第1面と反対側の第2面に前記第1波長に対する第3反射層を有するレーザ媒質と、
前記第2面に配置されるか、又は前記第2面より光軸の後方側に配置される、前記第2波長に対する第4反射層と、
前記第1反射層および前記第3反射層の間で前記第1波長の光を共振させる第1共振器と、
前記第2反射層および前記第4反射層の間で前記第2波長の光を共振させる第2共振器と、
前記積層半導体層と前記レーザ媒質との間に配置され、前記積層半導体層及び前記レーザ媒質の少なくとも一方で発生された熱を排熱する排熱部と、を備え、
前記積層半導体層の光軸及び前記レーザ媒質の光軸は、一軸上に配置される、電子機器。
(21)第1波長に対する第1反射層と、前記第1波長の面発光を行う活性層と、を有する積層半導体層と、
前記積層半導体層の光軸の後方側に配置され、前記積層半導体層と対向する第1面と反対側の第2面に前記第1波長に対する第2反射層を有するレーザ媒質と、
前記レーザ媒質の対向する第1側面及び第2側面に沿って配置される第1反射部材及び第2反射部材と、
前記第1側面に沿って設けられ、第2波長の光を入力する光入力部と、
前記第2側面に沿って設けられ、前記第2波長の光を増幅して出力する光出力部と、
前記第1反射層および前記第2反射層の間で前記第1波長の光を共振させる第1共振器と、を備え、
前記レーザ媒質は、前記第1反射部材及び前記第2反射部材の間で前記第2波長の光を複数回往復させる増幅媒質であり、
前記積層半導体層の光軸及び前記レーザ媒質の光軸は、一軸上に配置される、レーザ増幅素子。
(22)前記第1共振器による前記第1波長の光の共振動作により前記レーザ媒質を励起させた状態で、前記光入力部から前記第2波長の光を入射して、前記増幅媒質で前記第2波長の光を複数回往復させた後に、前記光出力部から、前記第2波長の光を増幅して出力する、(21)に記載のレーザ増幅素子。
(23)前記積層半導体層と前記レーザ媒質の間に配置され、前記積層半導体層及び前記レーザ媒質の少なくとも一方で発生された熱を排熱する第1排熱部材を備え、
前記積層半導体層の光軸、前記第1排熱部材の光軸、及び前記レーザ媒質の光軸は、一軸上に配置される、(21)又は(22)に記載のレーザ増幅素子。
(24)前記第1排熱部材の熱伝導率は、前記レーザ媒質の熱伝導率よりも高い、(23)に記載のレーザ増幅素子。
(25)前記レーザ媒質の前記積層半導体層に対向する端面とは反対側の端面に接合され、前記レーザ媒質で発生された熱を排熱する第2排熱部材を備える、(23)又は(24)に記載のレーザ増幅素子。
(26)前記第2排熱部材の熱導電率は、前記レーザ媒質の熱伝導率よりも高い、(25)に記載のレーザ増幅素子。
(27)前記積層半導体層、前記第1排熱部材、及び前記レーザ媒質の側面に接合され、前記積層半導体層及び前記レーザ媒質の少なくとも一方から前記第1排熱部材に伝達された熱を放熱する冷却部材を備える、(23)乃至(26)のいずれか一項に記載のレーザ増幅素子。
(28)前記第1排熱部材は、前記第1排熱部材を貫通して前記積層半導体及び前記レーザ媒質に接合される複数のビア部材を有し、
前記複数のビア部材の熱伝導率は、前記第1排熱部材の熱伝導率よりも高い、(23)乃至(27)のいずれか一項に記載のレーザ増幅素子。
(29)前記第1反射部材及び前記第2反射部材は、入射された光が集光されないように反射させる凸面ミラー部材である、(21)乃至(28)のいずれか一項に記載のレーザ増幅素子。
(30)前記第1反射部材及び前記第2反射部材は、前記第1側面及び前記第2側面に配置される、半導体材料、金属材料、及び誘電体材料の少なくとも一つを積層させた多層膜である、(21)乃至(29)のいずれか一項に記載のレーザ増幅素子。
Claims (20)
- 第1波長に対する第1反射層と、前記第1波長の面発光を行う活性層と、を有する積層半導体層と、
前記積層半導体層の光軸の後方側に配置され、前記積層半導体層と対向する第1面に第2波長に対する第2反射層および前記第1面と反対側の第2面に前記第1波長に対する第3反射層を有するレーザ媒質と、
前記第2面に配置されるか、又は前記第2面より光軸の後方側に配置される、前記第2波長に対する第4反射層と、
前記第1反射層および前記第3反射層の間で前記第1波長の光を共振させる第1共振器と、
前記第2反射層および前記第4反射層の間で前記第2波長の光を共振させる第2共振器と、
前記積層半導体層と前記レーザ媒質との間に配置され、前記積層半導体層及び前記レーザ媒質の少なくとも一方で発生された熱を排熱する排熱部と、を備え、
前記積層半導体層の光軸及び前記レーザ媒質の光軸は、一軸上に配置される、レーザ素子。 - 前記排熱部は、前記積層半導体層と前記レーザ媒質との間に配置され、前記レーザ媒質よりも熱伝導率が高い第1部材を有する、請求項1に記載のレーザ素子。
- 前記レーザ媒質に対向する側の前記第1部材の表面の一部またはすべてに配置され、前記積層半導体層及び前記レーザ媒質よりも熱伝導率の高い金属層を備える、請求項2に記載のレーザ素子。
- 前記積層半導体層の側面、前記第1部材の側面、及び前記レーザ媒質の側面に接合され、前記第1部材に伝達された熱を放熱する第2部材を備える、請求項2に記載のレーザ素子。
- 前記積層半導体層を支持する基板と、
前記基板上のパッドと前記積層半導体層の電極とに接続されるボンディングワイヤと、を備え、
前記第2部材は、前記積層半導体層及び前記レーザ媒質の側面と、前記ボンディングワイヤとを覆うように配置される、請求項4に記載のレーザ素子。 - 前記第1部材は、サファイア及びダイヤモンドの少なくとも一方を含み、
前記第2部材は、金属材料を含む、請求項4に記載のレーザ素子。 - 前記積層半導体層に対向する側の前記第1部材の表面に配置され、前記第1波長の光を透過させ、かつ前記第2波長の光を反射させる保護層を備える、請求項2に記載のレーザ素子。
- 前記第1部材は、前記第1波長の光を透過させる第1領域と、前記第1領域の周囲に配置され前記レーザ媒質より熱伝導率の高い第2領域と、を有する、請求項2に記載のレーザ素子。
- 前記第2領域は、絶縁材料又は金属材料である、請求項8に記載のレーザ素子。
- 前記第2領域は、前記第1領域を取り囲むように配置され、
前記第2領域の外周面又は前記外周面の角部は、前記第1領域の中心位置から等距離に位置する、請求項8に記載のレーザ素子。 - 前記積層半導体層、前記排熱部、及びレーザ媒質の面方向に、複数の前記第1共振器と複数の前記第2共振器とを備える、請求項1に記載のレーザ素子。
- 前記排熱部は、前記積層半導体層と前記レーザ媒質との間に配置されるエアギャップを有する、請求項1に記載のレーザ素子。
- 前記第2反射層から前記第4反射層の間に配置され、前記第2波長の光のビーム径を拡大させる第1光学素子を備える、請求項1に記載のレーザ素子。
- 前記第1共振器は、前記第1波長の光を光軸方向に集光させる第2光学素子を有する、請求項1に記載のレーザ素子。
- 前記レーザ媒質と反対側の第3面に前記第4反射層を有する可飽和吸収体を備え、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記可飽和吸収体の光軸は、一軸上に配置される、請求項1に記載のレーザ素子。 - 前記積層半導体層、前記レーザ媒質、および前記可飽和吸収体は一体に接合されている、請求項15に記載のレーザ素子。
- 前記レーザ媒質と前記可飽和吸収体との間、又は前記可飽和吸収体よりも光軸後方側に配置され、前記第2波長の光の偏光状態を制御する偏光制御素子を備える、請求項15に記載のレーザ素子。
- 前記第4反射層は、前記第2共振器における出力結合鏡である、請求項1に記載のレーザ素子。
- 前記積層半導体層は、前記第1反射層よりも前記レーザ媒質に近い側に配置され、前記第1波長に対する第5反射層を有し、
前記第5反射層は、前記第1波長の光の一部を透過させる、請求項1に記載のレーザ素子。 - レーザ素子と、
前記レーザ素子から光を放出する制御を行う制御部と、を備える電子機器であって、
前記レーザ素子は、
第1波長に対する第1反射層と、前記第1波長の面発光を行う活性層と、を有する積層半導体層と、
前記積層半導体層の光軸の後方側に配置され、前記積層半導体層と対向する第1面に第2波長に対する第2反射層および前記第1面と反対側の第2面に前記第1波長に対する第3反射層を有するレーザ媒質と、
前記第2面に配置されるか、又は前記第2面より光軸の後方側に配置される、前記第2波長に対する第4反射層と、
前記第1反射層および前記第3反射層の間で前記第1波長の光を共振させる第1共振器と、
前記第2反射層および前記第4反射層の間で前記第2波長の光を共振させる第2共振器と、
前記積層半導体層と前記レーザ媒質との間に配置され、前記積層半導体層及び前記レーザ媒質の少なくとも一方で発生された熱を排熱する排熱部と、を備え、
前記積層半導体層の光軸及び前記レーザ媒質の光軸は、一軸上に配置される、電子機器。
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JP2002353563A (ja) * | 2001-05-24 | 2002-12-06 | Rohm Co Ltd | 半導体発光素子およびその製法 |
US20120170109A1 (en) * | 2009-07-30 | 2012-07-05 | Centre National De La Recherche Scientifique-Cnrs | Device for controlling optical frequency, method of manufacturing such a device |
WO2018083877A1 (ja) * | 2016-11-02 | 2018-05-11 | ソニー株式会社 | 発光素子及びその製造方法 |
JP2019176119A (ja) * | 2018-03-29 | 2019-10-10 | 株式会社ニデック | 固体レーザ装置 |
WO2020137136A1 (ja) * | 2018-12-25 | 2020-07-02 | ソニー株式会社 | レーザ装置 |
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JPH1084169A (ja) * | 1996-07-26 | 1998-03-31 | Commiss Energ Atom | 直軸キャビティ半導体レーザーによる光学的ポンピングを備えた固体マイクロレーザー |
JP2002353563A (ja) * | 2001-05-24 | 2002-12-06 | Rohm Co Ltd | 半導体発光素子およびその製法 |
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