WO2022249357A1 - 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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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1123—Q-switching
- H01S3/113—Q-switching using intracavity saturable absorbers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
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
- the excitation laser and the Q-switched solid-state laser share a resonator.
- the cavity length can be shortened on the Q-switched solid-state laser side, but the cavity length on the pumping laser side becomes longer because it resonates including the solid-state laser medium.
- the diffraction loss generally increases, so the optical density in the semiconductor cavity decreases. That is, when the cavity length on the surface emitting laser side becomes longer, the excitation light density in the solid-state laser medium decreases. This reduces the output of the solid-state laser.
- the present disclosure provides a laser element and an electronic device capable of suppressing diffraction loss during laser resonance.
- 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;
- the first resonator has an optical element for condensing the light of the first wavelength in an optical axis direction,
- a laser element is provided in which the optical axis of the laminated semiconductor layer, the optical axis of the laser medium, and the optical axis of the optical element are arranged on one axis.
- the optical element may have a concave mirror.
- the concave mirror may have a multilayer film structure in which at least one of a semiconductor material, a metal material, and a dielectric material is laminated.
- At least one of the first reflective layer and the third reflective layer may have the concave mirror.
- the laminated semiconductor layer has a first semiconductor layer having a concave end face on the first reflective layer side,
- the concave mirror may be stacked on the first semiconductor layer.
- the laser medium has a concave end surface on the side of the third reflective layer,
- the concave mirror may be laminated on the end surface of the laser medium.
- the optical element may be bonded to an end surface of the laser medium opposite to the side facing the laminated semiconductor layer.
- the optical element has a first transparent material layer that transmits light of the second wavelength, a first end surface of the first transparent material layer joined to the laser medium is flat, and a second end surface on the opposite side of the first end surface is concave;
- the concave mirror may be arranged along the second end surface.
- An end surface of the second transparent material layer opposite to the joint surface with the first transparent material layer may be a flat surface.
- the optical element may have a light refracting member that refracts incident light in the optical axis direction.
- the laminated semiconductor layer has a fifth reflective layer disposed closer to the laser medium than the active layer and transmitting part of the light of the first wavelength,
- the light refraction member may be disposed between the fifth reflective layer and the second reflective layer.
- the light refraction member may have a convex end surface on the side of the laminated semiconductor layer facing the laser medium.
- the optical element is bonded to an end surface of the laminated semiconductor layer facing the laser medium;
- the optical refraction member may have a convex end surface on a side of the optical element facing the laser medium.
- the optical element has a transparent material layer that is bonded to the photorefractive member and transmits the light of the first wavelength;
- the transparent material layer has a lower refractive index than the photorefractive member,
- a joint surface of the transparent material layer with the photorefractive member may be concave, an end surface opposite to the joint surface may be flat, and an end surface of the laser medium may be joined to the flat surface.
- the light refraction member may have a convex end face on the side of the laser medium facing the laminated semiconductor layer.
- the second reflective layer may be arranged along the convex end surface.
- the optical element has a transparent material layer that is bonded to the photorefractive member and transmits the light of the first wavelength;
- a bonding surface of the transparent material layer with the photorefractive member may be concave, an end surface opposite to the bonding surface may be flat, and an end surface of the laminated semiconductor layer may be bonded to the flat surface.
- Some of the semiconductor layers including the active layer in the laminated semiconductor layer are divided into a plurality of divided regions by an insulator, Each of the plurality of divided regions may have the first resonator and the second resonator.
- a saturable absorber having the fourth reflective layer on a third surface opposite to the laser medium;
- the optical axis of the laminated semiconductor layer, the optical axis of the laser medium, the optical axis of the saturable absorber, and the optical axis of the optical element are arranged on one axis,
- the laminated semiconductor layer, the laser medium, and the saturable absorber may be integrally bonded.
- 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;
- the first resonator has an optical element for condensing the light of the first wavelength in an optical axis direction,
- An electronic device is provided in which the optical axis of the laminated semiconductor layer, the optical axis of the laser medium, and the optical axis of the optical element are arranged on one axis.
- FIG. 1 is a diagram showing the basic configuration of a laser device according to the present disclosure
- FIG. Sectional drawing of the laser element which concerns on a 1st specific example.
- Sectional drawing of the laser element which concerns on a 2nd specific example Sectional drawing of the laser element which concerns on a 3rd specific example.
- Sectional drawing of the laser element which concerns on a 4th specific example Sectional drawing of the laser element which concerns on a 5th specific example.
- Cross-sectional view of a laser device according to the sixth specific example Sectional drawing of the laser element which concerns on a 7th specific example.
- FIG. 11 is a cross-sectional view of a laser device according to an eighth specific example; Sectional drawing of the laser element which concerns on a 9th specific example.
- 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
- FIG. 15 is a block diagram showing an example of the functional configuration of the camera and CCU shown in FIG. 14; 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 since light of the first wavelength is resonated between the laminated semiconductor layer and the solid-state laser medium, the cavity length is longer than when light is resonated only by the laminated semiconductor layer. Therefore, as described above, the diffraction loss increases and the pumping light density in the solid-state laser medium decreases. Therefore, the laser device according to the present disclosure is provided with an optical element for suppressing diffraction loss.
- a 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.
- An optical element for condensing the light of the first wavelength in the optical axis direction is provided inside the first resonator.
- This optical element has, for example, a concave mirror.
- the concave mirror is at least one of the first reflective layer and the third reflective layer provided on both sides of the first cavity.
- the optical element comprises, for example, a photorefractive member.
- the light refracting member refracts incident light in the optical axis direction.
- the light refraction member is provided between the fifth reflective layer (also called an intermediate mirror) in the laminated semiconductor layers and the second reflective surface of the 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 emits surface light of the first wavelength ⁇ 1.
- the clad layers 6 and 8 are, for example, non-doped 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.
- the first reflective layer R1 and the fifth reflective layer R5 for example, an electrically conductive semiconductor distributed reflective layer (DBR: Distributed Bragg Reflector) is used.
- DBR Distributed Bragg Reflector
- the first reflective layer R1 is p-DBR and the fifth reflective layer R5 is n-DBR.
- p-DBR and n-DBR are a multi-layer reflective layer in which low refractive index layers and high refractive index layers are alternately laminated.
- Corresponding dopants eg carbon for p-DBR and silicon for n-DBR are added to the p-DBR and n-DBR.
- the p-DBR and n-DBR are formed of Al z1 Ga 1-z1 As/Al z2 Ga 1-z2 As (0 ⁇ z1 ⁇ z2 ⁇ 1). Also, it is desirable that z2 is not 1 in order to distinguish from an oxide layer, which will be described later.
- An n-contact layer 33 is arranged between the fifth reflective layer R5 and the n-GaAs substrate 5 .
- 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 (eg, AlAs layer) 31 on the cladding layer side of the first reflective layer R1 is removed by dry etching or the like and is oxidized and altered to become a post-oxidation layer (eg, Al 2 O 3 layer) 32 . This allows electrical and optical confinement of the light of the first wavelength.
- 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. More specifically, the active layer 7 includes quantum well layers and barrier layers that are alternately laminated to have compressive strain, such as Al x1 In y1 Ga 1-x1-y1 As layers and Al x3 In y3 It is formed of a Ga 1-x3-y3 As layer. Also, it may be a multi-junction structure via a tunnel junction.
- 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, deposition of an electrode film, etc., enable driving by current injection.
- MOCVD metal organic chemical vapor deposition
- MBE molecular beam epitaxy
- processes such as mesa etching for element isolation, formation of an insulating film, deposition of an electrode film, etc., enable driving by current injection.
- the laminated structure of the excitation light source 2 shown in FIG. Laminated semiconductor layer is an example, and the material, layer structure, and semiconductor process during manufacture of each semiconductor layer are not limited to the above description.
- 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 conductivity type of the laminated semiconductor layer 2 may be opposite to that described above, and the substrate 5 may be a non-doped substrate.
- 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.
- the fourth reflective layer R4 is provided on the end surface of the saturable absorber 4, but the fourth reflective layer R4 may be arranged on the rear side of the optical axis from the laser pulse emission surface of the saturable absorber 4. good.
- 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. even if the fourth reflective layer R4 is arranged on the front side of the optical axis relative to the saturable absorber 4, the light of the second wavelength ⁇ 2 is resonated between the second reflective layer R2 and the fourth reflective layer R4. need to let
- 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 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 side wall of the trench extending from the first reflective layer R1 to the n-contact layer 33 with a conductive material 35 through the insulating film 34 to bring it into contact with the n-contact layer 33. be.
- 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 a surface layer with these arithmetic mean roughnesses.
- 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 There is a film (AR: Anti-Reflection) and the like. It is desirable to arrange different kinds of dielectric multilayer films according to need.
- 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. It does not matter which film formation method is applied. Also, the characteristics of the dielectric multilayer film can be arbitrarily selected.
- 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. Further, by applying a long-wavelength transmission filter film to the third reflective layer R3, it is possible to prevent the first wavelength from entering the saturable absorber and prevent malfunction of the Q switch.
- the 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 with a photonic crystal structure that separates 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 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.
- Diffraction loss is caused by the presence of light emitted from the first resonator 11 while the light emitted from the active layer 7 resonates in the first resonator 11 . If the emitted light can be kept within the resonator, the loss can be reduced. It is known that a resonator using a concave mirror as a reflecting mirror of the resonator can reduce diffraction loss more than a parallel plate mirror. No specific method for suppressing the diffraction loss of the resonator has been proposed.
- a specific configuration of the laser element for suppressing the diffraction loss of the first resonator 11 will be described below.
- a laser device according to the present disclosure comprises an optical element in addition to the basic structure shown in FIG.
- the optical element is provided in the first resonator 11 .
- the optical element has a function of condensing the light of the first wavelength in the optical axis direction. Since a plurality of configurations can be considered as a specific configuration of the optical element, laser elements having optical elements having different configurations will be described in order below.
- FIG. 2 is a cross-sectional view of the laser device 1 according to the first specific example.
- the laser element 1 in FIG. 2 has a configuration in which an excitation light source 2, a solid-state laser medium 3, and a saturable absorber 4 are integrally joined, as in FIG.
- the electrodes E1 and E2 shown in FIG. 1 are omitted.
- the laser element 1 in FIG. 2 has an optical element 9.
- the optical element 9 of FIG. 2 has a concave mirror 10 .
- the concave mirror 10 in FIG. 2 is the concave first reflective layer R1 of the excitation light source 2 .
- the optical element 9 in FIG. 2 is obtained by processing the first reflective layer R1 of the excitation light source 2 into a concave shape.
- the first wavelength ⁇ 1 resonate the light of
- the light of the first wavelength ⁇ 1 reflected by the first reflective layer R1 is reflected in the optical axis direction of the first resonator 11, as indicated by the dashed line in FIG. It advances in the direction in which light is collected. As a result, the proportion of light that goes out of the first resonator 11 is reduced, and diffraction loss can be suppressed.
- the laser device 1 of FIG. 2 is of a bottom emission type, and on a substrate 5, an n-contact layer 33, a fifth reflective layer R5, a clad layer 6, an active layer 7, a clad layer 8, and a concave mirror formation layer 41 are formed. are laminated in order, the surface of the concave mirror forming layer 41 is processed into a convex shape by dry etching or the like, and at least one of a semiconductor material, a metal material, and a dielectric material is laminated on the formed convex surface.
- a concave mirror 10 made of a film is arranged by vapor deposition, sputtering, or the like.
- the multilayer film 42 has a concave shape when viewed from the inside of the first resonator 11, it is called a concave mirror 10 in this specification.
- the material of the concave mirror forming layer 41 is not particularly limited as long as it is a transparent material that transmits the light of the first wavelength ⁇ 1.
- the concave mirror 10 is a first reflective layer R1 that reflects the light of the first wavelength ⁇ 1 in a direction of convergence in the optical axis direction of the first cavity 11 .
- the laser element 1 in FIG. 2 is obtained by processing the first reflective layer R1 in FIG. 1 into a convex shape, and diffraction loss can be suppressed without adding a new member.
- FIG. 3 is a cross-sectional view of the laser device 1 according to the second specific example.
- the laser element 1 of FIG. 3 also has an optical element 9 consisting of a concave mirror 10 .
- the laser device 1 of FIG. 3 is of the top emission type.
- the substrate 5 of the excitation light source 2 is arranged on the side opposite to the solid-state laser medium 3, and the DBR on the substrate 5 side is originally the first reflecting layer which is the resonator mirror of the first resonator 11. Corresponds to R1.
- FIG. 1 is a cross-sectional view of the laser device 1 according to the second specific example.
- the laser element 1 of FIG. 3 also has an optical element 9 consisting of a concave mirror 10 .
- the laser device 1 of FIG. 3 is of the top emission type.
- the substrate 5 of the excitation light source 2 is arranged on the side opposite to the solid-state laser medium 3, and the DBR on the substrate 5 side is originally the first reflecting layer which is the resonator mirror of the
- the DBR on the substrate 5 side is removed, the surface of the substrate 5 is processed into a convex surface by dry etching or the like, and a multilayer film 42 for the excitation wavelength is formed on the convex surface by vapor deposition, sputtering, or the like.
- the concave mirror 10 is formed when the This concave mirror 10 is a first reflective layer R1 that reflects the light of the first wavelength ⁇ 1 in the direction of convergence in the optical axis direction.
- the concave mirror 10 is formed by processing the end surface of the top emission type substrate 5 into a convex surface, so diffraction loss can be suppressed without adding a new member.
- FIG. 4 is a cross-sectional view of the laser device 1 according to the third specific example.
- the laser element 1 of FIG. 4 has an optical element 9 on the saturable absorber 4 side of the solid-state laser medium 3 .
- This optical element 9 has a concave mirror 10 .
- This concave mirror 10 functions as a third reflective layer R3.
- the light of the first wavelength ⁇ 1 incident on the concave mirror 10 is reflected in the direction of convergence in the optical axis direction.
- the concave mirror 10 in FIG. 4 is obtained by processing the surface of the solid-state laser medium 3 into a convex shape by dry etching or the like, and arranging the concave mirror 10 composed of a multilayer film 42 on the formed convex surface by vapor deposition, sputtering, or the like.
- the concave mirror 10 is a third reflective layer R3 that reflects the incident light of the first wavelength ⁇ 1 in the direction of convergence in the optical axis direction of the first resonator 11 . Also, the concave mirror 10 transmits the light of the second wavelength ⁇ 2.
- a transparent material layer 43 is formed on the concave mirror 10 arranged on the end face of the solid-state laser medium 3, the surface of the transparent material layer 43 is flattened, and the saturable absorber 4 is bonded to this transparent material layer 43.
- the transparent material layer 43 may be any material as long as it allows the light of the second wavelength ⁇ 2 to pass therethrough, and any specific material may be used.
- the transparent material layer 43 is formed by vapor deposition, sputtering, or the like to be thicker than the height of the concave mirror 10, and is subjected to CMP (Chemical Mechanical Polishing) to a roughness (for example, Ra of about 1 nm) at which the saturable absorber 4 can be bonded. ) to planarize. Thereby, the transparent material layer 43 and the saturable absorber 4 can be stably brought into surface contact with each other.
- CMP Chemical Mechanical Polishing
- a non-reflective coating layer 44 may be arranged between the transparent material layer 43 and the saturable absorber 4 .
- the antireflection coating layer 44 By arranging the antireflection coating layer 44, the possibility that the light of the second wavelength ⁇ 2 is reflected at the interface between the transparent material layer 43 and the saturable absorber 4 is eliminated.
- FIG. 5 is a cross-sectional view of the laser device 1 according to the fourth specific example.
- the laser element 1 of FIG. 5 has an optical element 9 bonded to the end face of the solid-state laser medium 3 .
- the optical element 9 is a member provided separately from the solid-state laser medium 3 and is a first transparent material layer.
- the third reflective layer R3 is arranged on the end face of the solid-state laser medium 3 on the saturable absorber 4 side, but in FIG.
- a concave mirror 10 composed of a multilayer film 42 is arranged, and this concave mirror 10 functions as a third reflective layer R3.
- the first transparent material layer which is the base material of the optical element 9, has a flat surface for surface contact with the solid-state laser medium 3 and convex end surfaces.
- the first transparent material layer which is the base material of the optical element 9 in FIG. 5, may be any transparent material that transmits the light of the first wavelength ⁇ 1 and the second wavelength ⁇ 2, and the specific material does not matter.
- the surface of the optical element 9 is processed into a convex shape by dry etching or the like.
- a concave mirror 10 made of a multilayer film 42 arranged on a convex surface reflects light of the first wavelength ⁇ 1 and transmits light of the second wavelength ⁇ 2.
- a transparent material layer (also referred to as a second transparent material layer) 43 that transmits the light of the second wavelength ⁇ 2 is deposited and planarized in the same manner as in FIG. Therefore, the saturable absorber 4 is stably brought into surface contact with the transparent material layer 43 .
- a non-reflection coating layer 44 may be arranged on the interface between the transparent material layer 43 and the saturable absorber 4 .
- FIG. 6 is a sectional view of the laser device 1 according to the fifth specific example.
- a laser device 1 in FIG. 6 includes an optical element 9 having a concave mirror 10a corresponding to the concave mirror 10 in FIG. 2 and a concave mirror 10b corresponding to the concave mirror 10 in FIG.
- the concave mirror 10a has a multilayer film 42a arranged along the concave surface
- the concave mirror 10b has a multilayer film 42b arranged along the concave surface.
- Both the concave mirror 10 in FIG. 2 and the concave mirror 10 in FIG. 4 reflect the light of the first wavelength ⁇ 1 in a direction to converge the incident light in the optical axis direction of the first resonator 11 . Therefore, by providing both the concave mirror 10 of FIG. 2 and the concave mirror 10 of FIG. 4, the diffraction loss can be further suppressed, and the light intensity of the laser output can be further improved.
- At least one of the first reflective layer R1 and the third reflective layer R3 of the first resonator 11 is a concave mirror 10, so that the first wavelength ⁇ 1 Diffraction loss is suppressed by reflecting the light in the direction of convergence along the optical axis.
- an optical device 9 having a light refracting member is provided inside the excitation light source 2, and the light of the first wavelength ⁇ 1 is condensed. It is refracted in the direction to make it.
- FIG. 7 is a cross-sectional view of the laser device 1 according to the sixth specific example.
- the laser element 1 of FIG. 7 has an optical element 9 having a light refraction member 46 inside the excitation light source 2 .
- the light refraction member 46 of FIG. 7 is formed by processing the surface of the substrate in the excitation light source 2 into a convex shape by dry etching or the like.
- the light refracting member 46 functions as a convex lens, refracts the light of the first wavelength ⁇ 1 incident from the first reflecting surface side in a parallel direction, and emits the first wavelength ⁇ 1 incident from the third reflecting surface side.
- the light of wavelength ⁇ 1 is refracted in the direction of convergence in the optical axis direction and emitted.
- the transparent material layer 47 is made of a material having a smaller refractive index than the material of the substrate of the excitation light source 2, and must be formed thick enough to flatten the convex surface.
- FIG. 7 shows a bottom emission type laser device 1, but in the case of a top emission type, DBR, which is the material of the first reflective layer R1 in FIG. 7, is arranged near the second reflective layer R2. . Since the DBR cannot be processed into a convex shape, the light refracting member 46 is formed by processing the substrate 5 bonded to the DBR into a convex shape.
- FIG. 8 is a cross-sectional view of the laser device 1 according to the seventh specific example.
- the laser element 1 of FIG. 8 has an optical element 9 composed of a light refraction member 46 between the excitation light source 2 and the solid-state laser medium 3 .
- This light refraction member 46 functions as a convex lens.
- the convex light refraction member 46 is formed by processing the substrate of the excitation light source 2, whereas in FIG. 8, the convex light refraction member 46 is arranged separately from the excitation light source 2. do.
- the light refracting member 46 in FIG. 8 is formed by forming a first transparent material layer 47 having a thickness that allows formation of a convex surface on the end face of the excitation light source 2, and processing it into a convex shape by dry etching or the like.
- a second transparent material layer 47 having a smaller refractive index than the first transparent material layer 47 is formed on the convex surface by vapor deposition, sputtering, or the like. and planarized by CMP, the solid-state laser medium 3 is bonded.
- a non-reflective coating layer 44 may be arranged between the light refraction member 46 and the substrate 5 of the excitation light source 2 .
- FIG. 9 is a sectional view of the laser device 1 according to the eighth specific example.
- the end face of the solid-state laser medium 3 on the excitation light source 2 side is processed into a convex shape by dry etching or the like, and a multilayer film 42 is formed on the convex face to form a light refraction member 46.
- the multilayer film 42 of the light refraction member 46 functions as a second reflective layer R2 that transmits light of the first wavelength ⁇ 1 and reflects light of the second wavelength ⁇ 2.
- the light refraction member 46 functions as a convex lens for the light of the first wavelength ⁇ 1.
- a transparent material layer 47 that transmits light of the first wavelength ⁇ 1 is formed on the multilayer film 42 and planarized by CMP or the like. Thereby, the transparent material layer 47 and the excitation light source 2 can be firmly bonded.
- the optical element 9 as the light refraction member 46 was shown.
- the fine periodic structure is, for example, a Fresnel lens, a metalens, a photonic crystal lens, or the like.
- the optical element 9 having a structure having a refractive index distribution in the plane intersecting the optical axis can also focus the light of the first wavelength ⁇ 1 in the optical axis direction.
- the structure having a refractive index distribution is, for example, a GRIN lens, or a base material such as glass that has been modified by irradiating it with a laser beam.
- the excitation light source 2 is one form of VCSEL as described above, it is also possible to arrange the laser light sources in a one-dimensional or two-dimensional array.
- FIG. 10 is a cross-sectional view of the laser device 1 according to the ninth specific example.
- some semiconductor layers including the active layer 7 are divided into a plurality of divided regions, and each divided region has a first resonator 11 and a second resonator 12 .
- the laser element 1 in FIG. 10 shows an example in which the concave mirror 10 is used as the first reflecting surface R1 in each divided area, similarly to FIG.
- the optical element 9 is not limited to the first specific example, and may have the same aspect as any of the second to eighth specific examples described above.
- the heat exhaust member is, for example, sapphire, diamond, or the like, which has a refractive index and a coefficient of linear expansion equivalent to those of YAG and a thermal conductivity higher than that of YAG.
- sapphire for example, sapphire, diamond, or the like, which has a refractive index and a coefficient of linear expansion equivalent to those of YAG and a thermal conductivity higher than that of YAG.
- the pulse width of the laser pulse emitted from the laser device 1 can be shortened. Become. The shorter the pulse width of the laser pulse, the higher the peak power, so optical damage is more likely to occur than before.
- Optical damage occurs not only inside the second resonator 12 that generates the Q-switched laser pulse, but also inside the pumping light source 2 because return light is generated on the side of the pumping light source 2 (pumping light source 2).
- the semiconductor layer 2 having a laminated structure that constitutes 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. For this reason, it is desirable that a plurality of Short Wave Pass Filters (SWPF) are arranged at a plurality of interfaces between the excitation light source 2 and the solid-state laser medium 3 while reducing the cavity length.
- SWPF Short Wave Pass Filters
- the laser device 1 and the laser device according to the present disclosure employ a laminated structure in which the optical axis of the excitation light and the optical axis of the laser light are coaxial.
- the laser element 1 and the laser device according to the present disclosure do not require complicated positional and angular alignments, and have a simplified structure. Therefore, it is easy to downsize the laser element 1 and the laser device. It is also possible to simultaneously form a plurality of laser devices 1 according to the present disclosure by stacking or bonding a plurality of materials on the same semiconductor substrate. Since each laser element 1 can be separated by dicing in a post-process, high-performance laser elements 1 can be mass-produced at low cost.
- FIG. 11 is a diagram schematically showing the manufacturing process of the laser device 1 of the present disclosure.
- FIG. 11 shows a manufacturing process for forming the laser element 1 having the structure of FIG.
- a resist film 21 is applied onto the substrate 13 for the optical element 9 which is bonded to the end face of the solid laser medium on the saturable absorber 4 side, and the resist film 21 is coated with a resist film 21.
- a photomask 22 is placed on the surface and UV exposure is performed.
- step S ⁇ b>2 the exposed portions and the resist film 21 are removed by dry etching or the like to form a plurality of convex portions 23 on the third surface of the saturable absorber 4 .
- step S ⁇ b>3 a multilayer film 24 is formed on the plurality of convex portions 23 by vapor deposition, sputtering, or the like, and the concave mirror 10 is formed on the surface of the optical element 9 .
- step S4 the semiconductor layer 2 for the excitation light source 2, the solid-state laser medium 3, the optical element 9 processed in step S2, and the saturable absorber 4 are arranged vertically. Align. At that time, the alignment marks 25 provided at specific locations of the semiconductor layer 2, the solid-state laser medium 3, the optical element 9, and the saturable absorber 4 are photographed with a camera 26, so that the alignment marks 25 overlap vertically. , the semiconductor layer 2, the solid-state laser medium 3, the optical element 9, and the saturable absorber 4 are aligned and bonded. Next, as shown in step S5, individual laser elements 1 are obtained by dicing.
- the optical element 9 for condensing the light of the first wavelength ⁇ 1 in the optical axis direction is provided inside the first resonator 11, the light leaking from the first resonator 11 to the outside It is possible to reduce the ratio of the emitted light of the first wavelength ⁇ 1 and suppress the diffraction loss. By suppressing the diffraction loss, the light intensity of the laser light emitted from the laser element 1 can be increased.
- 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 pumping 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 above-described optical element 9 is provided inside the first resonator 11 .
- the optical element 9 is formed, for example, by processing the end face of the excitation light source 2 or the solid-state laser medium 3 into a convex shape, and can be formed without adding a new member. According to the laser device 1 according to the present disclosure, the reliability and mass productivity of the laser device 1 are improved, and a high-performance laser device 1 can be obtained at low cost.
- 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 device 1 in order to align the light emitting point of the excitation light source 2 and the center position of the concave mirror 10 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.
- the laser array 18 in which a plurality of laser elements 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 element 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. 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.
- FIG. 1 shows an example in which the laser device 1 has a saturable absorber 4 and emits short-pulse pulsed laser light. Even at 1, diffraction losses can occur.
- FIG. 13 is a diagram showing the basic configuration of the laser device 1 without the saturable absorber 4.
- FIG. A laser device 1 in FIG. 13 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 of the solid-state laser medium 3, or is arranged on the rear side of the optical axis from the second surface.
- FIG. 13 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.
- the fourth reflective layer R4 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 excitation light of the first wavelength ⁇ 1 is confined within the solid-state laser medium 3, and when the solid-state laser medium 3 is sufficiently excited and the output of the spontaneous emission light increases, the light of the second wavelength ⁇ 2 is emitted. It is emitted from the laser element 1 through the fourth 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 ⁇ 1 and reflects light of the second wavelength ⁇ 2.
- the light of the first wavelength ⁇ 1 in the first resonator 11 can be focused in the optical axis direction. can be obtained, and the diffraction loss can be suppressed.
- a medical imaging system is a medical system using imaging technology, such as an endoscope system or a microscope system.
- FIG. 14 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. 15 is a diagram showing an example of the configuration of an endoscope 5001 and a CCU (Camera Control Unit) 5039.
- FIG. 14 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 viewing.
- 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 disk.
- 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. 16 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. 16 schematically shows an operator 5067 performing an operation on a patient 5071 on a patient bed 5069 using the microsurgery system 5300 .
- the cart 5037 in the configuration of the microsurgery system 5300 is omitted from the illustration for simplicity, and the microscope device 5301 that replaces the endoscope 5001 is illustrated in a simplified manner.
- 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;
- the first resonator has an optical element for condensing the light of the first wavelength in an optical axis direction,
- the laser element wherein the optical axis of the laminated semiconductor layer, the optical axis of the laser medium, and the optical axis of the optical element are arranged on one axis.
- the optical device has a concave mirror.
- the concave mirror has a multilayer film structure in which at least one of a semiconductor material, a metal material, and a dielectric material is laminated.
- the laminated semiconductor layer includes a first semiconductor layer having a concave end face on the first reflective layer side; The laser device according to any one of (2) to (4), wherein the concave mirror is stacked on the first semiconductor layer.
- the laser medium has a concave end surface on the side of the third reflective layer;
- the optical element has a first transparent material layer that transmits light of the second wavelength; a first end surface of the first transparent material layer joined to the laser medium is flat, and a second end surface on the opposite side of the first end surface is concave;
- (9) having a second transparent material layer that is bonded to the second end face of the first transparent material layer and that transmits light of the second wavelength;
- the laser device according to (8) wherein the end surface of the second transparent material layer opposite to the joint surface with the first transparent material layer is a flat surface.
- the laser device according to (1) wherein the optical device has a light refracting member that refracts incident light in an optical axis direction.
- the laminated semiconductor layer has a fifth reflective layer arranged closer to the laser medium than the active layer and transmitting part of the light of the first wavelength;
- the laser device according to (10), wherein the light refraction member is arranged between the fifth reflective layer and the second reflective layer.
- the optical element has a transparent material layer that is bonded to the photorefractive member and transmits the light of the first wavelength;
- the transparent material layer has a lower refractive index than the photorefractive member, (13) a joint surface of the transparent material layer with the photorefractive member is concave, an end surface opposite to the joint surface is a flat surface, and an end surface of the laser medium is joined to the flat surface;
- the laser device according to . The laser device according to (10), wherein the light refraction member has a convex end face on the side of the laser medium facing the laminated semiconductor layer.
- the second reflective layer is arranged along the convex end surface.
- the optical element has a transparent material layer that is bonded to the photorefractive member and transmits the light of the first wavelength; (15 ) or the laser device according to (16). (18) part of the semiconductor layers including the active layer in the laminated semiconductor layer is divided into a plurality of divided regions by an insulator; The laser device according to any one of (1) to (17), wherein each of the plurality of divided regions has the first resonator and the second resonator.
- the optical axis of the laminated semiconductor layer, the optical axis of the laser medium, the optical axis of the saturable absorber, and the optical axis of the optical element are arranged on one axis,
- 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;
- the first resonator has an optical element for condensing the light of the first wavelength in an optical axis direction,
- An electronic device wherein an optical axis of the laminated semiconductor layer, an optical axis of the laser medium, and an optical axis of the optical element are arranged on one axis.
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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、を備え、
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光学素子を有し、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記光学素子の光軸は、一軸上に配置される、レーザ素子が提供される。
前記凹面ミラーは、前記第1半導体層に積層されてもよい。
前記凹面ミラーは、前記レーザ媒質の前記端面に積層されてもよい。
前記第1透明材料層の前記レーザ媒質に接合される第1端面は平坦面であり、前記第1端面の反対側の第2端面は凹面形状であり、
前記凹面ミラーは前記第2端面に沿って配置されてもよい。
前記第2透明材料層の前記第1透明材料層との接合面とは反対側の端面は、平坦面であってもよい。
前記光屈折部材は、前記第5反射層と前記第2反射層との間に配置されてもよい。
前記光屈折部材は、前記光学素子の前記レーザ媒質に対向する側に凸面形状の一端面を有してもよい。
前記透明材料層は、前記光屈折部材よりも屈折率が小さく、
前記透明材料層の前記光屈折部材との接合面は凹面形状であり、前記接合面の反対側の端面は平坦面であり、前記平坦面に前記レーザ媒質の端面が接合されてもよい。
前記透明材料層の前記光屈折部材との接合面は凹面形状であり、前記接合面の反対側の端面は平坦面であり、前記平坦面に前記積層半導体層の端面が接合されてもよい。
前記複数の分割領域のそれぞれは、前記第1共振器及び前記第2共振器を有してもよい。
前記積層半導体層の光軸、前記レーザ媒質の光軸、前記可飽和吸収体の光軸、及び前記光学素子の光軸は、一軸上に配置され、
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、を備え、
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光学素子を有し、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記光学素子の光軸は、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。
まず、第1共振器11の共振器長が長くなることで回折損失が大きくなる原因について説明する。ここで、回折損失は、活性層7から発せられる光が第1共振器11内で共振しているうちに第1共振器11の外に放出されてしまう光の存在により生じる。この放出されてしまう光を共振器内に留めることができればその損失を低減する事が出来る。共振器の反射ミラーとして、平行平板ミラーよりも凹面ミラーを用いた共振器の方が回折損失を低減できることが知られているが、2つの共振器が固体レーザ媒質を共有する構成において、一方の共振器の回折損失を抑制する具体的な手法は提案されていない。
図2は第1具体例に係るレーザ素子1の断面図である。図2のレーザ素子1は、図1と同様に、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。図2のレーザ素子1では、図1に示した電極E1、E2を省略している。
図3は第2具体例に係るレーザ素子1の断面図である。図3のレーザ素子1も、凹面ミラー10からなる光学素子9を備えている。図3のレーザ素子1は、トップエミッション型である。トップエミッション型の場合、励起光源2の基板5が固体レーザ媒質3とは反対側に配置され、本来的には基板5側のDBRが第1共振器11の共振器ミラーである第1反射層R1に相当する。図3では、基板5側のDBRを除去し、基板5の表面をドライエッチング等で凸面加工し、その凸面に励起波長に対する多層膜42を蒸着やスパッタ等により形成することで、共振器から見たときに凹面ミラー10を形成する。この凹面ミラー10は、第1波長λ1の光を光軸方向に集光させる向きに反射させる第1反射層R1である。
図4は第3具体例に係るレーザ素子1の断面図である。図4のレーザ素子1は、固体レーザ媒質3の可飽和吸収体4側に光学素子9を備えている。この光学素子9は、凹面ミラー10を有する。この凹面ミラー10は第3反射層R3として機能する。この凹面ミラー10に入射された第1波長λ1の光は、光軸方向に集光される向きに反射される。
図5は第4具体例に係るレーザ素子1の断面図である。図5のレーザ素子1は、固体レーザ媒質3の端面に接合される光学素子9を備えている。光学素子9は、固体レーザ媒質3とは別個に設けられる部材であり、第1透明材料層である。図1では、固体レーザ媒質3の可飽和吸収体4側の端面に第3反射層R3が配置されているが、図5では、光学素子9の端面が凸面形状に加工されて、この凸面に多層膜42からなる凹面ミラー10が配置され、この凹面ミラー10が第3反射層R3として機能する。このように、光学素子9の基材である第1透明材料層は、固体レーザ媒質3に面接触するための平坦面と、凸面形状の端面とを有する。
図6は第5具体例に係るレーザ素子1の断面図である。図6のレーザ素子1は、図2の凹面ミラー10に対応する凹面ミラー10aと、図4の凹面ミラー10に対応する凹面ミラー10bを有する光学素子9を備えている。凹面ミラー10aは凹面に沿って配置される多層膜42aを有し、凹面ミラー10bは凹面に沿って配置される多層膜42bを有する。
上述した第1~第5具体例に係るレーザ素子1は、第1共振器11の第1反射層R1と第3反射層R3の少なくとも一方を凹面ミラー10にすることで、第1波長λ1の光を光軸方向に集光される向きに反射させて、回折損失の抑制を図っている。これに対して、以下に説明する第7~第9具体例に係るレーザ素子1は、励起光源2の内部に光屈折部材を有する光学素子9を設けて、第1波長λ1の光を集光させる方向に屈折させるものである。
図8は第7具体例に係るレーザ素子1の断面図である。図8のレーザ素子1は、励起光源2と固体レーザ媒質3との間に、光屈折部材46からなる光学素子9を配置している。この光屈折部材46は、凸レンズとして機能する。図7では、励起光源2の基板を加工することで、凸面形状の光屈折部材46を形成するのに対し、図8では、励起光源2とは別個に、凸面形状の光屈折部材46を配置する。
図9は第8具体例に係るレーザ素子1の断面図である。図9のレーザ素子1は、固体レーザ媒質3の励起光源2側の端面をドライエッチング等により凸面形状に加工して、凸面に多層膜42を成膜することで、光屈折部材46を形成する。この光屈折部材46の多層膜42は、第1波長λ1の光を透過させて、第2波長λ2の光を反射させる第2反射層R2として機能する。これにより、光屈折部材46は、第1波長λ1の光に対する凸レンズとして機能する。光屈折部材46の多層膜42は凸面形状であるため、第1波長λ1の光を透過させる透明材料層47を多層膜42の上に成膜し、CMP等により平坦化させる。これにより、透明材料層47と励起光源2とを強固に接合させることができる。
励起光源2は、上述したようにVCSELの一形態であるため、一次元又は二次元方向にアレイ状にレーザ光源を配置することも可能である。
本開示によるレーザ素子1は、励起光源2と固体レーザ媒質3とを接合するため、励起光源2と固体レーザ媒質3とで熱的干渉が相互に起こり得る。熱的干渉が起きると、固体レーザ媒質3では、第1波長λ1から第2波長λ2への変換効率が低下する。また、励起光源2の内部の温度が上昇し、励起光源2のI-L特性(発光効率)が低下する。さらに、励起光源2内の活性層7の温度が上昇し、長期信頼性(MTTF:Mean Time To Failure)が悪化する。
図11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11は、図5の構造のレーザ素子1を形成する製造工程を示している。まず、図11の工程S1に示すように、固体レーザ媒体の可飽和吸収体4側の端面に接合される光学素子9用の基材13上にレジスト膜21を塗布し、レジスト膜21の上にフォトマスク22を配置して、UV露光を行う。
上述したように、本開示によるレーザ素子1では、第1波長λ1の光を光軸方向に集光させる光学素子9を第1共振器11内に設けるため、第1共振器11から外部に漏れ出す第1波長λ1の光の割合を減らすことができ、回折損失を抑制できる。回折損失を抑制することで、レーザ素子1から出射されるレーザ光の光強度を高めることができる。
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、回折損失が生じる可能性がある。
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14、図15を用いて説明する。図14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15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14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14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15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15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16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、を備え、
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光学素子を有し、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記光学素子の光軸は、一軸上に配置される、レーザ素子。
(2)前記光学素子は、凹面ミラーを有する、(1)に記載のレーザ素子。
(3)前記凹面ミラーは、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構造である、(2)に記載のレーザ素子。
(4)前記第1反射層及び前記第3反射層の少なくとも一方は、前記凹面ミラーを有する、(2)又は(3)に記載のレーザ素子。
(5)前記積層半導体層は、前記第1反射層側の端面が凹面形状の第1半導体層を有し、
前記凹面ミラーは、前記第1半導体層に積層される、(2)乃至(4)のいずれか一項に記載のレーザ素子。
(6)前記レーザ媒質は、前記第3反射層側の端面が凹面形状であり、
前記凹面ミラーは、前記レーザ媒質の前記端面に積層される、(2)乃至(4)のいずれか一項に記載のレーザ素子。
(7)前記光学素子は、前記レーザ媒質の前記積層半導体層に対向する側とは反対側の端面に接合される、(2)乃至(4)のいずれか一項に記載のレーザ素子。
(8)前記光学素子は、前記第2波長の光を透過させる第1透明材料層を有し、
前記第1透明材料層の前記レーザ媒質に接合される第1端面は平坦面であり、前記第1端面の反対側の第2端面は凹面形状であり、
前記凹面ミラーは前記第2端面に沿って配置される、(7)に記載のレーザ素子。
(9)前記第1透明材料層の前記第2端面に接合され、前記第2波長の光を透過させる第2透明材料層を有し、
前記第2透明材料層の前記第1透明材料層との接合面とは反対側の端面は、平坦面である、(8)に記載のレーザ素子。
(10)前記光学素子は、入射された光を光軸方向に屈折させる光屈折部材を有する、(1)に記載のレーザ素子。
(11)前記積層半導体層は、前記活性層よりも前記レーザ媒質の側に配置され前記第1波長の光の一部を透過させる第5反射層を有し、
前記光屈折部材は、前記第5反射層と前記第2反射層との間に配置される、(10)に記載のレーザ素子。
(12)前記光屈折部材は、前記積層半導体層の前記レーザ媒質に対向する側に凸面形状の端面を有する、(11)に記載のレーザ素子。
(13)前記光学素子は、前記積層半導体層の前記レーザ媒質に対向する側の端面に接合され、
前記光屈折部材は、前記光学素子の前記レーザ媒質に対向する側に凸面形状の一端面を有する、(11)に記載のレーザ素子。
(14)前記光学素子は、前記光屈折部材に接合されて前記第1波長の光を透過させる透明材料層を有し、
前記透明材料層は、前記光屈折部材よりも屈折率が小さく、
前記透明材料層の前記光屈折部材との接合面は凹面形状であり、前記接合面の反対側の端面は平坦面であり、前記平坦面に前記レーザ媒質の端面が接合される、(13)に記載のレーザ素子。
(15)前記光屈折部材は、前記レーザ媒質の前記積層半導体層に対向する側に凸面形状の端面を有する、(10)に記載のレーザ素子。
(16)前記第2反射層は、前記凸面形状の端面に沿って配置される、(15)に記載のレーザ素子。
(17)前記光学素子は、前記光屈折部材に接合されて前記第1波長の光を透過させる透明材料層を有し、
前記透明材料層の前記光屈折部材との接合面は凹面形状であり、前記接合面の反対側の端面は平坦面であり、前記平坦面に前記積層半導体層の端面が接合される、(15)又は(16)に記載のレーザ素子。
(18)前記積層半導体層における前記活性層を含む一部の半導体層は、絶縁体で複数の分割領域に分割されており、
前記複数の分割領域のそれぞれは、前記第1共振器及び前記第2共振器を有する、(1)乃至(17)のいずれか一項に記載のレーザ素子。
(19)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、前記可飽和吸収体の光軸、及び前記光学素子の光軸は、一軸上に配置され、
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、(1)乃至(18)のいずれか一項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、を備え、
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光学素子を有し、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記光学素子の光軸は、一軸上に配置される、電子機器。
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、を備え、
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光学素子を有し、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記光学素子の光軸は、一軸上に配置される、レーザ素子。 - 前記光学素子は、凹面ミラーを有する、請求項1に記載のレーザ素子。
- 前記凹面ミラーは、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構造である、請求項2に記載のレーザ素子。
- 前記第1反射層及び前記第3反射層の少なくとも一方は、前記凹面ミラーを有する、請求項2に記載のレーザ素子。
- 前記積層半導体層は、前記第1反射層側の端面が凹面形状の第1半導体層を有し、
前記凹面ミラーは、前記第1半導体層に積層される、請求項2に記載のレーザ素子。 - 前記レーザ媒質は、前記第3反射層側の端面が凹面形状であり、
前記凹面ミラーは、前記レーザ媒質の前記端面に積層される、請求項2に記載のレーザ素子。 - 前記光学素子は、前記レーザ媒質の前記積層半導体層に対向する側とは反対側の端面に接合される、請求項2に記載のレーザ素子。
- 前記光学素子は、前記第2波長の光を透過させる第1透明材料層を有し、
前記第1透明材料層の前記レーザ媒質に接合される第1端面は平坦面であり、前記第1端面の反対側の第2端面は凹面形状であり、
前記凹面ミラーは前記第2端面に沿って配置される、請求項7に記載のレーザ素子。 - 前記第1透明材料層の前記第2端面に接合され、前記第2波長の光を透過させる第2透明材料層を有し、
前記第2透明材料層の前記第1透明材料層との接合面とは反対側の端面は、平坦面である、請求項8に記載のレーザ素子。 - 前記光学素子は、入射された光を光軸方向に屈折させる光屈折部材を有する、請求項1に記載のレーザ素子。
- 前記積層半導体層は、前記活性層よりも前記レーザ媒質の側に配置され前記第1波長の光の一部を透過させる第5反射層を有し、
前記光屈折部材は、前記第5反射層と前記第2反射層との間に配置される、請求項10に記載のレーザ素子。 - 前記光屈折部材は、前記積層半導体層の前記レーザ媒質に対向する側に凸面形状の端面を有する、請求項11に記載のレーザ素子。
- 前記光学素子は、前記積層半導体層の前記レーザ媒質に対向する側の端面に接合され、
前記光屈折部材は、前記光学素子の前記レーザ媒質に対向する側に凸面形状の一端面を有する、請求項11に記載のレーザ素子。 - 前記光学素子は、前記光屈折部材に接合されて前記第1波長の光を透過させる透明材料層を有し、
前記透明材料層は、前記光屈折部材よりも屈折率が小さく、
前記透明材料層の前記光屈折部材との接合面は凹面形状であり、前記接合面の反対側の端面は平坦面であり、前記平坦面に前記レーザ媒質の端面が接合される、請求項13に記載のレーザ素子。 - 前記光屈折部材は、前記レーザ媒質の前記積層半導体層に対向する側に凸面形状の端面を有する、請求項10に記載のレーザ素子。
- 前記第2反射層は、前記凸面形状の端面に沿って配置される、請求項15に記載のレーザ素子。
- 前記光学素子は、前記光屈折部材に接合されて前記第1波長の光を透過させる透明材料層を有し、
前記透明材料層の前記光屈折部材との接合面は凹面形状であり、前記接合面の反対側の端面は平坦面であり、前記平坦面に前記積層半導体層の端面が接合される、請求項15に記載のレーザ素子。 - 前記積層半導体層における前記活性層を含む一部の半導体層は、絶縁体で複数の分割領域に分割されており、
前記複数の分割領域のそれぞれは、前記第1共振器及び前記第2共振器を有する、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、前記可飽和吸収体の光軸、及び前記光学素子の光軸は、一軸上に配置され、
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、を備え、
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光学素子を有し、
前記積層半導体層の光軸、前記レーザ媒質の光軸、及び前記光学素子の光軸は、一軸上に配置される、電子機器。
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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 |
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 |
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 |
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 |
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