LASER ELEMENT AND ELECTRONIC DEVICE

Abstract

The excitation light output is improved without generating heat or reducing operating life. A laser element comprises: a laminated semiconductor layer, which includes a first reflective layer used for light of a first wavelength and an active layer that performs surface light emission at the first wavelength; a second reflective layer, which is located closer to a light-emitting surface than the laminated semiconductor layer and is used for the light of the first wavelength; and a polarization splitting element, which resonates and multiplexes each of the orthogonally polarized rays contained in the light emitted by the laminated semiconductor layer individually between the first reflective layer and the second reflective layer.

Description

[Technical field]

[0001] The present disclosure relates to a laser element and an electronic device. [State of the art]

[0002] Laser technology is applied to various fields, such as micromanufacturing, medical devices, and distance measurement. Short-pulse laser technology is particularly expected to be applied to high-precision machining or high-efficiency wavelength conversion. A Q-switched solid-state laser among these technologies can achieve high peak power exceeding kilowatts (kW) with a relatively simple configuration and is therefore used in a wide range of applications (see PTL 1). [Citation list][Patent literature]

[0003] [PTL 1] WO 2021 / 106757 A1 [Summary][Technical Problem]

[0004] A multi-junction structure has been proposed, which is provided with a plurality of active layers within an excitation light source comprising a laminated semiconductor layer. This type of excitation light source has a higher thermal resistance than that of an edge-emitting laser (EEL) and has a rollover point of light output. Therefore, when the power of the excitation light source is increased to increase the light output, a junction temperature rises, and the mean time to failure (MTTF) of an element decreases.

[0005] PTL 1 discloses a structure obtained by combining laminated semiconductor layers with a solid-state laser medium for a Q-switch. A first resonator formed by the laminated semiconductor layer, which is the excitation light source, and the solid-state laser medium, and a second resonator formed by a solid-state laser medium and a saturable absorber are adjacent, making it possible to excite the solid-state laser medium at a high intensity in the first resonator.

[0006] It is possible to increase the average output of Q-switch light by performing spatial multiplexing using an optical lens or performing multiplexing using polarization. However, the waveform of the Q-switch light oscillated by an excitation light-emitting source includes jitter, and even if the waveform is multiplexed, it is not possible to improve the overall peak power. On the other hand, even if the light output of the excitation light-emitting source is increased, an upper limit of the peak intensity of the Q-switch light is determined due to a limit of the excitation light output for the reason described above.

[0007] Therefore, the present disclosure provides a laser element and an electronic device that can improve excitation light output without generating heat and reducing an operating lifetime. [Solution to the problem]

[0008] To solve the above problem, the present disclosure provides a laser element comprising: a laminated semiconductor layer including a first reflection layer used for light of a first wavelength and an active layer performing surface light emission at the first wavelength; a second reflection layer disposed closer to a light-emitting surface side than the laminated semiconductor layer and used for the light of the first wavelength; and a polarization splitting element that individually resonates and multiplexes each of the orthogonally polarized rays contained in the light emitted from the laminated semiconductor layer between the first reflection layer and the second reflection layer.

[0009] The laminated semiconductor layer may comprise a plurality of laminated semiconductor regions associated with the orthogonally polarized beams, and the polarization splitting element can resonate and multiplex a corresponding polarized beam between the first reflection layer and the second reflection layer for each of the plurality of laminated semiconductor regions individually.

[0010] The polarization splitting element may include a first surface in contact with a light emitting surface of the laminated semiconductor layer, and a second surface disposed on an opposite side to the first surface and between the first reflection layer and the second reflection layer.

[0011] The orthogonally polarized beams may comprise orthogonally polarized beams of different wavelengths, and the polarization splitting element can individually resonate and multiplex each of the orthogonally polarized beams including the orthogonally polarized beams of different wavelengths between the first reflection layer and the second reflection layer.

[0012] The orthogonally polarized beams may include a transverse magnetic (TM) polarized beam and a transverse electric (TE) polarized beam, and the polarization splitting element may individually resonate and multiplex each of the TE polarized beam and the TM polarized beam between the first reflection layer and the second reflection layer.

[0013] The polarization splitting element can multiplex the TE polarized beam with the TM polarized beam within the polarization splitting element.

[0014] The polarization splitting element may comprise a laminated body obtained by alternately laminating a plurality of polarization splitting films and a plurality of reflection films at a distance from each other, the laminated body may have a cross-sectional area obtained by cutting the laminated body in a direction of 45 degrees in a normal direction of a lamination surface, and the polarization splitting element may be arranged such that the normal direction of the cross-sectional area is parallel to a normal direction of the laminated semiconductor layer.

[0015] The polarization splitting element may comprise a birefringent material for splitting the light emitted from the laminated semiconductor layer into the orthogonally polarized rays.

[0016] The laser element may comprise a laser medium arranged closer to the light emitting surface side than the polarization splitting element and oscillating at a second wavelength different from the first wavelength.

[0017] The laser element may comprise: a third reflection layer formed on a first end face of the laser medium on one side of the polarization splitting element and is used for light of the second wavelength; and a fourth reflection layer disposed on a second end face of the laser medium on a side opposite to the first end face and used for the light of the second wavelength.

[0018] The third reflection layer may be arranged closer to the light emitting surface side than the second reflection layer.

[0019] The third reflection layer may be arranged between the polarization splitting element and the second reflection layer.

[0020] The third reflection layer may be in contact with an end surface of the polarization splitting element.

[0021] The fourth reflection layer may be in contact with the second reflection layer or may be arranged closer to the light-emitting surface side than the second reflection layer.

[0022] The laser element may comprise a saturable absorber arranged closer to the light emitting surface side than the laser medium.

[0023] The laser element may comprise: a third reflection layer disposed on an end face of the laser medium on a side opposite to the polarization splitting element and used for light of the second wavelength; and a fourth reflection layer arranged on the light-emitting surface side of the saturable absorber and used for the light of the second wavelength.

[0024] The third reflection layer may be arranged closer to the light emitting surface side than the second reflection layer.

[0025] The second reflective layer may be arranged between the third reflective layer and the fourth reflective layer.

[0026] Each of the laminated semiconductor layer, the polarization splitting element, the laser medium, and the saturable absorber may be divided into a plurality of regions arranged at a predetermined interval in association with a plurality of light-emitting units that emit pulse laser light of the second wavelength.

[0027] The present disclosure provides an electronic device comprising: a control unit that performs control to emit light from the laser element, and the laser element includes: a laminated semiconductor layer comprising a first reflection layer used for light of a first wavelength and an active layer performing surface light emission at the first wavelength, a second reflection layer arranged closer to a light-emitting surface side than the laminated semiconductor layer and used for the light of the first wavelength, and a polarization splitting element that individually resonates and multiplexes each of a plurality of polarized rays included in the light emitted from the laminated semiconductor layer between the first reflection layer and the second reflection layer. [Short description of the drawing] [ Fig. 1] Fig. 1 is a schematic sectional view of a laser element according to a first embodiment. [ Fig. 2] Fig. 2 is a schematic sectional view of a laser element and a plan view seen from a light emission surface side according to a comparative example. [ Fig. 3] Fig. 3 is a diagram showing a relationship between a current of an excitation light source and a light output in the laser element in Fig. 2 illustrates. [ Fig. 4] Fig. 4 is a schematic sectional view of the laser element according to a second embodiment. [ Fig. 5] Fig. 5 is a view schematically illustrating a manufacturing method of a polarization splitting element. [ Fig. 6A] Fig. 6A is a diagram illustrating an example in which a TM polarized beam and a TE polarized beam are multiplexed substantially at a center in a thickness direction of the polarization splitting element. [ Fig. 6B] Fig. 6B is a diagram illustrating an example in which the TM polarized beam and the TE polarized beam are multiplexed in a region shifted from the center in the thickness direction of the polarization splitting element. [ Fig. 7] Fig. 7 is a schematic sectional view of the laser element according to a third embodiment. [ Fig. 8] Fig. Figure 8 is a diagram illustrating a construction example of a polarization splitting film. [ Fig. 9] Fig. 9 is a schematic sectional view of the laser element according to a fourth embodiment. [ Fig. 10] Fig. 10 is a schematic sectional view of the laser element according to a fifth embodiment. [ Fig. 11] Fig. 11 is a schematic sectional view of the laser element according to a sixth embodiment. [ Fig. 12] Fig. 12 is a schematic sectional view of the laser element according to a seventh embodiment. [ Fig. 13] Fig. 13 is a schematic sectional view of the laser element according to an eighth embodiment. [ Fig. 14] Fig. 14 is a schematic sectional view showing respective layers of the laser element in Fig. 13 illustrates this in more detail. [ Fig. 15] Fig. 15 is a plan view and a cross-sectional view illustrating a plurality of laser elements arranged in an array. [ Fig. 16A] Fig. 16A is a sectional view of a laser gain element according to the present disclosure. [ Fig. 16B] Fig. 16B is a perspective view of the laser gain element according to the present disclosure. [ Fig. 17] Fig. 17 is a diagram illustrating an example of a schematic configuration of an endoscopic system. [ Fig. 18] Fig. 18 is a block diagram illustrating an example of a functional configuration of a camera and a CCU used in Fig. 20 are illustrated. [ Fig. 19] Fig. 19 is a diagram illustrating an example of a schematic configuration of a microsurgical system. [Description of the embodiment]

[0028] Embodiments of a laser element and an electronic device are described below with reference to the drawings. Although main components of the laser element and the electronic device are mainly described below, the laser element and the electronic device may include components and functions that are not illustrated or explained. The following description does not exclude components or functions that are not illustrated or described. (First embodiment)

[0029] Fig. 1 is a schematic sectional view of a laser element 1 according to the first embodiment. As shown in Fig. 1, the laser element 1 according to the first embodiment includes an excitation light source 2 including a first reflection layer R1 and an active layer, a second reflection layer R2, and a polarization splitting element 10.

[0030] The laser element 1 according to the first embodiment has an integrated laminated structure that can be manufactured using a semiconductor process technology, and thus has good mass productivity and stability of a laser output.

[0031] The excitation light source 2 is the laminated semiconductor layer. The excitation light source 2 is hereinafter referred to as the laminated semiconductor layer 2. The laminated semiconductor layer 2 is a type of surface-emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser). Unlike the VCSEL, the second reflection layer R2, which is at least one of mirrors constituting a resonator, is provided outside the laminated semiconductor layer 2, which is a main body of the excitation light source 2. The second reflection layer R2 is, for example, an external resonator mirror. The laminated semiconductor layer 2 is also referred to as a Vertical External-Cavity Surface Emitting Laser (VECSEL).

[0032] The laminated semiconductor layer 2 includes the first reflection layer R1, which is used for light of a first wavelength λ1, and the active layer that performs surface light emission at the first wavelength λ1. A detailed layer configuration of the laminated semiconductor layer 2 will be described later. The second reflection layer R2 is arranged closer to a light-emitting surface side than the laminated semiconductor layer 2. The first reflection layer R1 and the second reflection layer R2 form a first resonator 11, which resonates light of the first wavelength λ1.

[0033] The polarization splitting element 10 is a flat plate-shaped element provided between the first resonator 11, which polarizes and splits light from the excitation light source 2. The polarization splitting element 10 multiplexes orthogonally polarized rays while uniquely determining a polarization direction. That is, the polarization splitting element 10 individually resonates and multiplexes each of the orthogonally polarized rays contained in the light emitted from the laminated semiconductor layer 2 constituting the excitation light source 2 between the first reflection layer R1 and the second reflection layer R2. The internal structure of the polarization splitting element 10 is irrelevant. A specific example of the polarization splitting element 10 is a polarizing beam splitter (PBS).For example, the inside of the polarization splitting element 10 is provided with a first optical element 13 that allows a first polarized beam to transmit and reflect a second polarized beam, and a second optical element 14 that reflects the second polarized beam such that the first polarized beam is transmitted through the first optical element 13 and performs a resonant operation between the first reflection layer R1 and the second reflection layer R2, and the second polarized beam is reflected by the second optical element 14 and the first optical element 13 and performs a resonant operation between the first reflection layer R1 and the second reflection layer R2.

[0034] The polarization splitting element 10 includes a first surface in contact with the light emitting surface of the laminated semiconductor layer 2, and a second layer disposed on a side opposite to the first surface and between the first reflection layer and the second reflection layer.

[0035] Fig. Fig. 2 is a schematic sectional view of a laser element 100 and a plan view as seen from a light-emitting surface side according to a comparative example. The laser element 100 in Fig. 2 uses a configuration in which the excitation light source 2, formed by the laminated semiconductor layer 2, a solid-state laser medium 3 for a Q-switch, and a saturable absorber 4 are arranged in this order. A uniform material layer 15 that does not control polarization can be arranged between the excitation light source 2 and the solid-state laser medium 3. This material layer 15 can be, for example, a support substrate that supports the excitation light source 2.

[0036] The laser element 100 in Fig. 2 comprises the first resonator 11, which resonates at the first wavelength λ1, and a second resonator 12, which resonates at the second wavelength λ2. The second resonator 12 is also referred to as a Q-switch solid-state laser resonator. The solid-state laser medium 3 in Fig. 2 is used for both the first resonator 11 and the second resonator 12. The first resonator 11 performs a resonant operation between the excitation light source 2 and the solid-state laser medium 3, and the second resonator 12 performs a resonant operation between the solid-state laser medium 3 and the saturable absorber 4.

[0037] Light of the first wavelength λ1 emitted from the excitation light source 2 and resonated by the first resonator 11 excites the solid-state laser medium 3. When the power of the excitation light of the first wavelength λ1 is accumulated in the solid-state laser medium 3 and the solid-state laser medium 3 enters a sufficiently excited state, the light absorption rate of the saturable absorber 4 rapidly decreases, the second resonator 12 resonates the light of the second wavelength λ2 between the third reflection layer and the fourth reflection layer, and the saturable absorber 4 emits a Q-switch laser pulse. Fig. 2 illustrates an example in which the shape of a light emitting unit 20 is circular.

[0038] The excitation light source 2 in Fig. 2 comprises the laminated semiconductor layer 2, and therefore the volume of the active layer in the laminated semiconductor layer 2 is limited. Although a multi-junction structure has also been proposed, which is provided with a plurality of active layers in the laminated semiconductor layer 2, the excitation light source 2 in Fig. 2 has a lower thermal conductivity than an edge-emitting laser, the active layer has a smaller volume, and therefore, the light output cannot be increased. Increasing the power of the excitation light source 2 to increase the light output increases the junction temperature and significantly reduces the operating lifetime of the laser element 1.

[0039] Fig. 3 is a diagram showing a relationship between a current of the excitation light source 2 and a light output in the laser element 100 in Fig. 2. When the current flowing to the excitation light source 2 reaches a predetermined value, as shown in Fig. As illustrated in Figure 3, the light output reaches an upper limit, and as the current continues to flow, the junction temperature rises and the light output decreases.

[0040] Although the light emitted by the excitation light source 2 comprises a plurality of polarized beams, the first resonator 11 performs random resonant operation regardless of the types of polarized beams. Only light energy is transferred from the first resonator 11 to the second resonator 12 without selecting a specific polarization.

[0041] In contrast, in the laser element 1 according to the Fig. In the first embodiment illustrated in FIG. 1, the laminated semiconductor layer 2 constituting the excitation light source 2 is divided into a plurality of laminated semiconductor regions in association with orthogonally polarized rays contained in the light emitted from the excitation light source 2. The plurality of laminated semiconductor regions emit spontaneous emission light of unpolarized rays. The polarization splitting element 10 individually resonates and multiplexes a corresponding polarized beam between the first reflection layer R1 and the second reflection layer R2 for each of the plurality of laminated semiconductor regions.

[0042] Consequently, for example, each of the two types of polarized beams individually performs a resonance operation between the first reflection layer R1 and the second reflection layer R2, so that the laser element 1 in Fig. 1 the light output emitted by the polarization splitting element 10 compared to Fig. 2 can be substantially doubled. That the light output emitted by the polarization splitting element 10 can be improved means that even if the current flowing to the excitation light source 2 is reduced compared to the laser element 100 in Fig. 2 is reduced, a high light output can be maintained and the current flowing to the excitation light source 2 can be reduced, so that it is possible to increase the operating life of the laser element 1.

[0043] The laser element 1 in Fig. 1 can have a bonded integrated structure through the semiconductor process. Consequently, it is possible to improve mass productivity, multiplex excitation light from a plurality of laminated semiconductor regions, increase excitation light output, and improve the mean time to failure (MTTF) of the laser element 1.

[0044] As described above, in the first embodiment, the orthogonally polarized rays contained in the light emitted from the laminated semiconductor layer 2 are resonated and multiplexed between the first reflection layer R1 and the second reflection layer R2, so that it is possible to increase the excitation light output without increasing the current flowing to the excitation light source 2. The excitation light source 2 is, for example, a semiconductor laser. The polarization splitting element 10 is laminated in the first resonator 11 using the semiconductor laser, and the polarized rays split in the polarization splitting element 10 are multiplexed, so that even the small laser element 1 can improve the excitation light output.Furthermore, even if the current flowing to the excitation light source 2 is reduced, it is possible to maintain the high excitation light source, so that it is possible to achieve a longer operating life of the laser element 1. (Second embodiment)

[0045] Fig. Fig. 4 is a schematic sectional view of a laser element 1a according to the second embodiment. In the laser element 1a in Fig. 4, the orthogonally polarized beams contained in the light emitted from the laminated semiconductor layer 2 include a transverse magnetic (TM) polarized beam and a transverse electric (TE) polarized beam. The polarization splitting element 10 individually resonates and multiplexes each of the TE polarized beam and the TM polarized beam between the first reflection layer R1 and the second reflection layer R2.

[0046] An example of the polarization splitting element 10 is considered a polarization conversion element (PS converter). The polarization conversion element can be manufactured by the same manufacturing method as that generally used for a liquid crystal projector. The polarization conversion element for the liquid crystal projector includes an aperture window arranged on an incident surface and a half-wave plate arranged on an emitting surface. The polarization conversion element according to the present embodiment does not require the aperture window and the half-wave plate and instead includes a polarization splitting film 16 on a multiplexing surface.

[0047] The polarization splitting element 10 employs a configuration in which the polarization splitting film 16 and a reflection film 17 arranged in a direction inclined by 45 degrees with respect to the normal direction of a light incident surface are alternately arranged along the light incident surface. The polarization splitting film 16 has the property of allowing the TM polarized beam to transmit and reflects the TE polarized beam. The reflection film 17 has the property of reflecting the TE polarized beam. Thus, the polarization splitting film 16 and the reflection film 17 are adjacently arranged along the light incident surface, so that the TM polarized beam resonates between the first reflection layer R1 and the second reflection layer R2 along the normal direction of the end face of the polarization splitting element 10.The TE polarized beam oscillates between the first reflection layer R1 and the second reflection layer R2 while being reflected by the reflection film 17 and the polarization splitting film 16. The TE polarized beam is reflected by the reflection film 17 and multiplexed with the TM polarized beam when further reflected by the polarization splitting film 16. Consequently, it is possible to increase the excitation light output from the polarization splitting film 16.

[0048] Even if a distance between the polarization splitting film 16 and the reflection film 17 is one mm or more, the laser element 1a according to the second embodiment can multiplex the TM polarized beam and the TE polarized beam.

[0049] Fig. 5 is a view schematically illustrating a manufacturing method for the polarization splitting element 10. A first substrate 22 including the polarization splitting film 16 formed on the end face of a base material layer 21 and a second substrate 24 including the reflection film 17 formed on the end face of a base material layer 23 are alternately laminated to form a laminated body 25. Materials of the base material layers 21 and 23 are not particularly important and must be a material that does not have a polarization splitting function.

[0050] Next, the laminated body 25 is cut at an inclination angle of 45 degrees with respect to the normal direction of a substrate surface, as shown by two-dot chain lines in Fig. 5 to manufacture a plurality of polarization splitting elements 10 comprising a plurality of the laminated bodies 25.

[0051] Since the thickness accuracy of the single first substrate 22 and second substrate 24 constituting the laminated body 25 is higher, the optical axes of the light to be multiplexed are consistent. Even if a positional shift occurs in a substrate surface direction at the time of bonding, the polarization splitting elements 10 exhibit robustness that does not cause a shift in the optical paths of the polarization splitting elements 10 to be fabricated.

[0052] Fig. 6A illustrates an example in which the TM polarized beam and the TE polarized beam are multiplexed substantially at a center in a thickness direction of the polarization splitting element 10, and Fig. 6B is a diagram illustrating an example in which the TM polarized beam and the TE polarized beam are multiplexed in a region shifted from the center in the thickness direction of the polarization splitting element 10.

[0053] In Fig. 6A and Fig. 6B, although the multiplexing positions of the TM polarized beam and the TE polarized beam are different due to a positional shift between the polarization splitting film 16 and the reflection film 17 in the substrate surface direction in the polarization splitting element 10, the optical paths of the multiplexed TM polarized beam and the TE polarized beam are not shifted. Consequently, robustness can be improved.

[0054] As described above, according to the second embodiment, by using the polarization splitting element 10 formed by alternately arranging the polarization splitting film 16 and the reflection film 17 arranged in the direction inclined by 45 degrees from the normal direction of the substrate surface along the light incident surface, it is possible to multiplex the TM polarized beam and the TE polarized beam included in excitation light within the polarization splitting element 10 and increase an excitation light output. (Third embodiment)

[0055] Fig. Fig. 7 is a schematic sectional view of a laser element 1b according to the third embodiment. The laser element 1b in Fig. 7 differs from the laser elements 1 and 1a according to the first and second embodiments in the internal structure of the polarization splitting element 10.

[0056] The polarization splitting element 10 according to the third embodiment includes the polarization splitting film 16 and a plurality of reflection films 17a and 17b. The plurality of reflection films 17a and 17b reflect the TE polarized rays of different wavelengths, respectively. The polarization splitting element 10 in Fig. 7 includes the polarization splitting film 16, the first reflection film 17a which reflects the TE polarized beam of wavelength λ1, and the second reflection film 17b which reflects the TE polarized beam of wavelength λ2.

[0057] Fig. Figure 8 is a diagram illustrating a construction example of the polarization splitting film 16. The horizontal axis indicates wavelength, and the vertical axis indicates transmittance. By changing the reflection properties of the first reflection film 17a and the second reflection film 17b, it is possible to adjust the wavelength band of the excitation light emitted from the polarization splitting element 10 and further improve the output of the excitation light. (Fourth embodiment)

[0058] Fig. Fig. 9 is a schematic sectional view of a laser element 1c according to the fourth embodiment. While the laser elements 1a and 1b in Fig. 4 and Fig. 7 comprise the polarization splitting element 10 formed by alternately arranging the polarization splitting film 16 and the reflection film 17, the laser element 1c in Fig. 9, the polarization splitting element 10, which is made of a birefringent material. The birefringent material is a material that splits incident light into orthogonally polarized beams depending on the polarization state of the incident light. The birefringent material typically splits the incident light into two polarized beams. One of the two polarized beams is called normal light (ordinary light), and the other is called abnormal light.

[0059] Fig. Figure 9 illustrates an example where the TM polarized beam is the normal light, and the TE polarized beam is the abnormal light among the two polarized beams split by the birefringent material. The TM polarized beam resonates between the first reflective layer R1 and the second reflective layer R2 along the normal direction of the substrate surface. The TE polarized beam travels diagonally in the birefringent material, is multiplexed with the TM polarized beam, and resonates between the first reflective layer R1 and the second reflective layer R2.

[0060] Examples of the birefringent material include rutile, which is a crystal of titanium dioxide (TiO2), a crystal of yttrium vanadate (YVO4), a crystal of lithium niobate (LiNbO3), and the like. Note that a specific type of birefringent material is not important. A material with high processability is preferred, so the transmittance with respect to the wavelength of the excitation light emitted from the excitation light source 2 is high and accuracy in a c-axis direction is obtained.

[0061] Rutile crystal is a birefringent material with high birefringence, and a transmitted light beam can be split into ordinary light and abnormal light. The polarization state of the abnormal light is orthogonal to the polarization state of ordinary light. Regarding the alignment of the excitation light source 2 and the polarization splitting element 10, it is possible to further increase the alignment accuracy according to the crystal cutting accuracy.

[0062] As described above, according to the fourth embodiment, the polarization splitting element 10 is formed using the birefringent material, so it is possible to simplify the internal structure of the polarization splitting element 10 and also simplify the manufacturing process. On the other hand, to multiplex the TM polarized beam and the TE polarized beam within the polarization splitting element 10, it is necessary to optimize the thickness of the polarization splitting element 10 and the birefringent material. (Fifth embodiment)

[0063] Fig. 10 is a schematic sectional view of a laser element 1d according to the fifth embodiment. The laser element 1d in Fig. 10 uses a configuration in which the solid-state laser medium 3 is provided for the laser elements 1, 1a, 1b, and 1c according to any one of the first to fourth embodiments. The solid-state laser medium 3 in Fig. 10 is arranged closer to the light-emitting surface side than the polarization splitting element 10. For example, the solid-state laser medium 3 is arranged closer to the light-emitting surface side than the second reflection layer R2.

[0064] The solid-state laser medium 3 oscillates at the second wavelength λ2, which is different from the first wavelength λ1. The solid-state laser medium 3 includes a third reflection layer R3 disposed on a first end face and a fourth reflection layer R4 disposed on a second end face on a side opposite the first end face. The third reflection layer R3 and the fourth reflection layer R4 reflect light of the second wavelength λ2. Then, the light of the second wavelength λ2 is resonated between the third reflection layer R3 and the fourth reflection layer R4.

[0065] The solid-state laser medium 3 contains, for example, an yttrium aluminum garnet (YAG) crystal Yb:YAG doped with ytterbium (Yb). In this case, the first wavelength λ1 of the first resonator 11 is 940 nm, and the second wavelength λ2 of the second resonator 12 is 1030 nm.

[0066] The solid-state laser medium 3 is not limited to Yb:YAG, for example, and can be at least one of Nd:YAG, Nd:YVO4, Nd:YLF, Nd:Glass, Yb:YAG, Yb:YLF, Yb:FAP, Yb:SFAP, Yb:YVO, Yb:Glass, Yb:KYW, Yb:BCBF, Yb:YCOB, Yb:GdCOB, and YB:YAB. The shape is not limited to crystal and does not preclude the use of ceramic materials.

[0067] Furthermore, the solid-state laser medium 3 may be a four-level system solid-state laser medium 3 or a quasi-three-level system solid-state laser 3. In this regard, since each crystal has a different suitable excitation wavelength (first wavelength λ1), it is necessary to select a semiconductor material of the active layer in the excitation light source 2 according to the material of the solid-state laser medium 3.

[0068] As described above, in the fifth embodiment, the solid-state laser medium 3 is arranged closer to the light-emitting surface than the polarization splitting element 10, making it possible to convert the wavelength of the emitted light. The laser element 1d according to the fifth embodiment can also be formed by a semiconductor process, making it possible to improve mass productivity. (Sixth Embodiment)

[0069] A laser element according to the sixth embodiment includes a saturable absorber provided closer to the light emission surface side than the solid-state laser medium 3.

[0070] Fig. 11 is a schematic sectional view of a laser element 1e according to the sixth embodiment. The laser element 1e in Fig. 11 uses a configuration in which the solid-state laser medium 3 and the saturable absorber 4 are provided for the laser elements 1 to 1c according to any one of the first to fourth embodiments. The solid-state laser medium 3 in Fig. 11 is arranged closer to the light emission surface side than the polarization splitting element 10, and the saturable absorber 4 is arranged closer to the light emission surface side than the solid-state laser medium 3.

[0071] The solid-state laser medium 3 and the saturable absorber 4 resonate at the second wavelength λ2, which is different from the first wavelength λ1. The end surface of the solid-state laser medium 3 on a side opposite the polarization splitting element 10 is provided with the third reflection layer R3, which is used for the light of the second wavelength λ2. The light-emitting surface side of the saturable absorber 4 is provided with the fourth reflection layer R4, which is used for the light of the second wavelength λ2. The third reflection layer R3 and the fourth reflection layer R4 reflect the light of the second wavelength λ2. Then, the light of the second wavelength λ2 is resonated between the third reflection layer R3 and the fourth reflection layer R4.

[0072] The saturable absorber 4 contains, for example, a YAG (Cr:YAG) crystal doped with Cr (chromium). The saturable absorber 4 is a material whose transmittance increases when the intensity of the incident light exceeds a predetermined threshold. The excitation light of the first wavelength λ1 from the first resonator 11 increases the transmittance of the saturable absorber 4 and emits a laser pulse of the second wavelength λ2. This is referred to as a Q-switch. V:YAG can also be used as the material of the saturable absorber 4. In this regard, other types of the saturable absorber 4 can be used. Furthermore, it is not prevented from using an active Q-switching element as the Q-switch.

[0073] As described above, in the sixth embodiment, the solid-state laser medium 3 and the saturable absorber 4 are arranged in series on the light emission surface side of the polarization splitting element 10, so that it is possible to emit a Q-switch pulse without a jitter using excitation light whose light output has been improved by being multiplexed by the polarization splitting element 10. (Seventh Embodiment)

[0074] A laser element according to the seventh embodiment uses the solid-state laser medium 3 for the first resonator 11 and the second resonator 12 in common.

[0075] Fig. Fig. 12 is a schematic sectional view of a laser element 1f according to the seventh embodiment. The laser element 1f in Fig. 12 includes the solid-state laser medium 3, which is arranged on the light-emitting surface side of the polarization splitting element 10. The first reflection layer R1 is arranged on an end surface on the side opposite the light-emitting surface of the laminated semiconductor layer 2, which is the excitation light source 2.

[0076] The third reflection layer R3 is arranged between the polarization splitting element 10 and the solid-state laser medium 3. The second reflection layer R2 and the fourth reflection layer R4 are arranged on the light-emitting surface side of the solid-state laser medium 3.

[0077] The laser element 1f in Fig. 12 includes the first resonator 11 and the second resonator 12. The first resonator 11 resonates the light of the first wavelength λ1 between the first reflection layer R1 and the second reflection layer R2. The second resonator 12 resonates the light of the second wavelength λ2 between the third reflection layer R3 and the fourth reflection layer R4. Thus, the solid-state laser medium 3 is shared between the first resonator 11 and the second resonator 12.

[0078] Consequently, by sharing the solid-state laser medium 3 between the first resonator 11 and the second resonator 12, it is possible to shorten the resonator length of the laser element 1f and emit laser light whose pulse width is small and whose laser peak power is high. (Eighth Embodiment)

[0079] A laser element according to the eighth embodiment includes the saturable absorber 4 arranged closer to the light emission surface than the solid-state laser medium 3 in the laser element 1f according to the seventh embodiment.

[0080] Fig. 13 is a schematic sectional view of a laser element 1g according to the eighth embodiment. The laser element 1g in Fig. 13 uses a configuration in which the solid-state laser medium 3 and the saturable absorber 4 are arranged in this order on the light-emitting surface side of the polarization splitting element 10. The laser element 1g in Fig. 13 includes the first reflection layer R1 to the fourth reflection layer R4. The first reflection layer R1 is disposed on the end surface opposite the light-emitting surface of the laminated semiconductor layer 2, which is the excitation light source 2. The second reflection layer R2 is disposed between the solid-state laser medium 3 and the saturable absorber 4. The third reflection layer R3 is disposed between the polarization splitting element 10 and the laser element 1g. The fourth reflection layer R4 is disposed on the light-emitting surface side of the saturable absorber 4.

[0081] The laser element 1g in Fig. 13 includes the first resonator 11 and the second resonator 12. The first resonator 11 resonates the light of the first wavelength λ1 between the first reflection layer R1 and the second reflection layer R2. The second resonator 12 resonates the light of the second wavelength λ2 between the third reflection layer R3 and the fourth reflection layer R4. The solid-state laser medium 3 is used jointly as the first resonator 11 and the second resonator 12.

[0082] It is possible to shorten the resonator lengths so that the laser element 1g in Fig. 13 which can emit Q-switch pulse laser light whose pulse width is small, whose laser peak power is high, and which has no jitter using excitation light whose light output has been improved by being multiplexed by the polarization splitting element 10.

[0083] Fig. 14 is a schematic sectional view showing respective layers of the laser element 1g in Fig. 13 illustrates this in more detail. The laminated semiconductor layer 2, which is the excitation light source 2, comprises two laminated semiconductor regions. Hereinafter, these two laminated semiconductor regions are referred to as a first laminated semiconductor region 2a and a second laminated semiconductor region 2b.

[0084] The TM polarized beam performs a resonant operation between the first laminated semiconductor region 2a, the polarization splitting element 10, and the solid-state laser medium 3. Further, the TE polarized beam emitted from the second laminated semiconductor region 2b and split by the polarization splitting element 10 is multiplexed with the TM polarized beam within the polarization splitting element 10.

[0085] The excitation light source 2, which is formed by the laminated semiconductor layer 2, which is to be divided into the first laminated semiconductor region 2a and the second laminated semiconductor region 2b, has a structure in which a substrate 5, an n-contact layer 33, a fifth reflection layer R5, a cladding layer 6, an active layer 7, a cladding layer 8, a pre-oxidation layer 31, and the first reflection layer R1 are laminated in sequence. It should be noted that the laser element 1g in Fig. 1 uses a lower emission type configuration in which the substrate 5 emits continuous wave (CW) excitation light, but may also use an upper emission type configuration in which CW excitation light is emitted from one side of the first reflection layer R1.

[0086] The substrate 5 is, for example, an n-GaAs substrate 5. The n-GaAs substrate 5 absorbs a certain rate of light of the first wavelength λ1, which is the excitation wavelength of the excitation light source 2, and is desirably as thin as possible. On the other hand, the n-GaAs substrate 5 desirably has a thickness such that the mechanical strength can be maintained at a time of a bonding process to be described later.

[0087] The active layer 7 performs surface light emission at the first wavelength λ1. The cladding layers 6 and 8 are, for example, AlGaAs cladding layers. The first reflection layer R1 reflects the light of the first wavelength λ1. The fifth reflection layer R5 has a certain transmittance with respect to the light of the first wavelength λ1. Distributed Bragg reflectors (DBRs), which enable electrical conduction, are used for the first reflection layer R1 and the fifth reflection layer R5. Current is injected from the outside through the first reflection layer R1 and the fifth reflection layer R5. Recombination and light emission occur in a quantum well in the active layer 7, and laser oscillation at the first wavelength λ1 is performed. A part of a pre-oxidation layer (e.g., AlAs layer) 31 on a cladding layer side of the first reflection layer R1 is oxidized as a post-oxidation layer (e.g., Al2O3 layer) 32.

[0088] The fifth reflection layer R5 is arranged, for example, on the n-GaAs substrate 5. For example, the fifth reflection layer R5 comprises the multilayer reflection film 17 made of Al z1 Ga1- z1 As / Al z2 Ga1- z2 As (0 ≤ z1 ≤ z2 ≤ 1) doped with an n-type dopant (e.g., silicon). The fifth reflection layer R5 is also referred to as an n-DBR. More specifically, the n-contact layer 33 is arranged between the fifth reflection layer R5 and the n-GaAs substrate 5.

[0089] The active layer 7 comprises a multiple quantum well layer formed by laminating, for example, an Al x1 In y1 Ga1- x1 - y1 As layer and an Al x3 In y3 Ga1- x3 - y3 As layer is formed.

[0090] The first reflection layer R1 comprises, for example, a multilayer reflection film of Alz3Ga1-z3As / AlZ4Ga1-z4As (0 ≤ z3 ≤ z4 ≤ 1) doped with a p-type dopant (e.g., carbon).

[0091] The semiconductor layers R5, 6, 7, 8, and R1 in the excitation light source 2 can be formed using a crystal growth method such as the metal organic chemical vapor deposition (MOCVD) method or the molecular beam epitaxy (MBE) method. Furthermore, it is possible to perform current injection driving after a process such as mesa etching for element isolation, formation of an insulating film, deposition of an electrode film, and the like after crystal growth.

[0092] The solid-state laser medium 3 is bonded to the end face on the side opposite the fifth reflection layer R5 of the n-GaAs substrate 5 of the excitation light source 2. Hereinafter, the end face on one side of the excitation light source 2 of the solid-state laser medium 3 is referred to as a first face F1, and an end face on one side of the saturable absorber 4 of the solid-state laser medium 3 is referred to as a second face F2. Further, a laser pulse emission face of the saturable absorber 4 is referred to as a third face F3, and an end face on the side of the solid-state laser medium 3 of the excitation light source 2 is referred to as a fourth face F4. Further, an end face on the side of the solid-state laser medium 3 of the saturable absorber 4 is referred to as a fifth face F5. Although in Fig. 1 is separated and illustrated for the sake of simplicity, the fourth surface F4 of the excitation light source 2 is bonded 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 bonded to the fifth surface F5 of the saturable absorber 4.

[0093] The laser element 1 in Fig. 1 comprises the first resonator 11 and the second resonator 12. The first resonator 11 resonates the light of the first wavelength λ1 between the first reflection layer R1 in the excitation light source 2 and the second reflection layer R2 in the solid-state laser medium 3. The second resonator 12 resonates the light of the second wavelength λ2 between the third reflection layer R3 in the solid-state laser medium 3 and the fourth reflection layer R4 in the saturable absorber 4.

[0094] The second resonator 12 is also referred to as the Q-switched solid-state laser resonator 12. The second reflection layer R2, which is a highly reflective layer, is provided in the solid-state laser medium 3 so that the first resonator 11 can perform a stable resonant operation. The normal excitation light source 2 includes a partial reflection mirror provided at a position of the second reflection layer R2 in Fig. 1 and emits the light of the first wavelength λ1 outwards. In contrast, in the laser element 1 in Fig. 1 uses the second reflection layer R2 as the highly reflective layer to use the second reflection layer R2 to capture power of the excitation light of the first wavelength λ1 in the first resonator 11.

[0095] As described above, three reflection layers (the first reflection layer R1, the fifth reflection layer R5, and the second reflection layer R2) are provided within the first resonator 11, which includes the excitation light source 2 and the solid-state laser medium 3. Thus, the first resonator 11 has a coupled cavity structure.

[0096] By capturing the power of the excitation light of the first wavelength λ1 in the first resonator 11, the solid-state laser medium 3 is excited. Consequently, Q-switch laser pulse oscillation occurs in the second resonator 12. The second resonator 12 resonates the light of the second wavelength λ2 between the third reflection layer R3 in the solid-state laser medium 3 and the fourth reflection layer R4 in the saturable absorber 4. While the third reflection layer R3 is a highly reflective layer, the fourth reflection layer R4 is a partially reflective layer. Although the fourth reflection layer R4 is formed on the end face of the saturable absorber 4 in Fig. 1, the fourth reflection layer R4 may be arranged closer to an optical axis back surface than the saturable absorber 4. The optical axis back surface is an emission direction of light on the optical axis. That is, the fourth reflection layer R4 does not necessarily have to be provided inside or on the front surface of the saturable absorber 4. The fourth reflection layer R4 is an output coupling mirror in the second resonator 12.

[0097] Although Fig. While Figure 1 illustrates the separate excitation light source 2, the solid-state laser medium 3, and the saturable absorber 4, these excitation light source 2, the solid-state laser medium 3, and the saturable absorber 4 are a laminated structure integrated by bonding using the bonding process. Examples of bonding processes include surface-activated bonding, atomic diffusion bonding, plasma-activated bonding, and the like. Alternatively, other bonding (adhesion) processes may be used.

[0098] In order to stably bond the solid-state laser medium 3 to the excitation light source 2, it is necessary to make the front surface of the n-GaAs substrate 5 in the excitation light source 2 flat. Therefore, as described above, electrodes E1 and E2 for injecting the current into the first reflection layer R1 and the fifth reflection layer R5 are desirably arranged so that at least the front surface of the n-GaAs substrate 5 is not exposed. In the example in Fig. 1, the electrodes E1 and E2 are arranged on the end face on one side of the first reflection layer R1 of the excitation light source 2. The electrode E1 is a p-electrode and conducts with the first reflection layer R1. The electrode E2 is an n-electrode and is formed by filling a conductive material 35 into an inner wall of a trench that reaches the n-contact layer 33 from the first reflection layer R1 with an insulating film 34 interposed therebetween. By arranging the electrodes E1 and E2 on the same end face of the excitation light source 2 as in Fig. 1, it is possible to solder and mount this end face onto a support substrate (not shown). Even when a plurality of laser elements 1 are arranged in an array, it is possible to achieve a shape that allows this end face on the support substrate by arranging the electrodes E1 and E2 on the same end face. It should be noted that the shapes and arrangement positions of the electrodes E1 and E2 shown in Fig. 1 are merely an example.

[0099] As described above, the laser element 1 in Fig. 1 the laminated structure, so that it is easy to manufacture the laminated structure and then to divide and singulate the laminated structure into a plurality of chips or to form a laser array obtained by arranging the plurality of laser elements 1 in the array on a substrate.

[0100] When the laser element 1 of the laminated structure is manufactured by the bonding process, the arithmetic mean roughness Ra of each front surface layer must be 1 nm or less, and is desirably 0.5 nm or less. Chemical mechanical polishing (CMP) is used to provide these front surface layers with the arithmetic mean roughness. Further, a dielectric multilayer film may be interposed between the respective layers, and the respective layers may be bonded with the interposed dielectric multilayer films to prevent light loss at the interface between the respective layers.For example, the refractive index n of the GaAs substrate surface 5, which is a base substrate of the excitation light source 2, with respect to a wavelength of 940 nm is 3.5, which is a high refractive index compared to YAG (n:1.8) and general dielectric multilayer film materials. Therefore, when the solid-state laser medium 3 and the saturable absorber 4 are bonded to the excitation light source 2, it is necessary to prevent light loss due to a refractive index mismatch. Specifically, an antireflection film (an AR coating film or an antireflection coating film) that does not reflect the light of the first wavelength λ1 of the first resonator 11 is desirably disposed between the excitation light source 2 and the solid-state laser medium 3.Furthermore, the anti-reflection film (the AR coating film or the anti-reflection coating film) is also desirably disposed between the solid-state laser medium 3 and the saturable absorber 4.

[0101] Polishing is difficult depending on the bonding materials. For example, a material such as SiO2, which is transparent to the first wavelength λ1 and the second wavelength λ2, can be formed as an underlayer for bonding. This SiO2 layer can be polished to an arithmetic mean roughness Ra = approximately 1 nm (desirably 0.5 nm or less) and used as an interface for bonding. Here, materials other than SiO2 can be used as the underlayer and are not limited to the materials. Note that an anti-reflection film may be provided between SiO2, which is the material of the underlayer, and the base material layer.

[0102] The dielectric multilayer film includes a shortwave pass filter (SWPF), a longwave pass filter (LWPF), a bandpass filter (BPF), an antireflection (AR) protective film, and the like, and is a coating layer formed by alternately laminating a high-refractive-index material layer and a low-refractive-index material layer. Various types of dielectric multilayer films are desirably arranged as needed. As a method for forming the dielectric multilayer films, the physical vapor deposition (PVD) method can be used; specifically, film formation methods such as vacuum deposition, ion-assisted deposition, and sputtering can be used. Which film formation method is used is irrelevant. Furthermore, the properties of the dielectric multilayer film can also be arbitrarily selected.For example, the third reflection layer R3 can be the shortwave pass filter, and the second reflection layer R2 can be the longwave pass filter. Furthermore, by applying the longwave pass filter to the second reflection layer R2, it is possible to prevent the first wavelength λ1 from penetrating the saturable absorber 4 and prevent erroneous operation of the Q-switch. Note that shortwave pass means that the light of the first wavelength λ1 is transmitted and the light of the second wavelength λ2 is reflected. Furthermore, longwave pass means that the light of the first wavelength λ1 is reflected and the light of the second wavelength λ2 is transmitted.

[0103] Furthermore, a diffraction grating may be provided within the second resonator 12 to convert the polarization state of a laser pulse to be emitted from random polarization to linear polarization. For example, a material such as SiO2 may be formed as a film and polished as an interface for bonding to the photonic crystal structure or a fine groove region of the diffraction grating.

[0104] In the laser element 1g in Fig. 14, the current is injected into the active layer 7 via the electrode of the excitation light source 2 to cause laser oscillation of the first wavelength λ1 in the first resonator 11 and excite the solid-state laser medium 3. Since the saturable absorber 4 is bonded to the solid-state laser medium 3, spontaneous emission light from the solid-state laser medium 3 is absorbed by the saturable absorber 4 at an initial stage of the occurrence of laser oscillation of the first wavelength λ1, whereby no optical feedback from the fourth reflection layer R4 on an emission surface side of the saturable absorber 4 and no Q-switch laser oscillation occurs.

[0105] Then, when the power of the excitation light of the first wavelength λ1 is accumulated in the solid-state laser medium 3 and the solid-state laser medium 3 enters a sufficiently excited state, an output of the spontaneous emission light increases. When the output exceeds a certain threshold, the light absorption rate of the saturable absorber 4 rapidly decreases, and the spontaneous emission light generated by the solid-state laser medium 3 can be transmitted through the saturable absorber 4. Consequently, the light of the first wavelength λ1 is emitted from the first resonator 11 of the solid-state laser medium 3, and the second resonator 12 resonates the light of the second wavelength λ2 between the second reflection layer R2 and the fourth reflection layer R4.Consequently, Q-switch laser oscillation occurs, and a Q-switch laser pulse is reflected via the fourth reflection layer R4 toward a space (a space on the right side in . Fig. 1) emitted.

[0106] As described above, in the laser element 1g according to the eighth embodiment, the TM polarized beam is multiplexed with the TE polarized beam to obtain a light output within the polarization splitting element 10, so that it is possible to increase the light output emitted from the polarization splitting element 10. The first resonator 11 resonates the light of the first resonator λ1 between the first reflection layer R1 disposed on the end surface on the side opposite to the light-emitting surfaces of the first laminated semiconductor region 2a and the second laminated semiconductor region 2b, and the second reflection layer R2 between the solid-state laser medium 3 and the saturable absorber 4.Furthermore, the second resonator 12 resonates the light of the second wavelength λ2 between the third reflection layer R3 between the polarization splitting element 10 and the solid-state laser medium 3 and the fourth reflection layer R4 on the light-emitting surface side of the saturable absorber 4. By sharing the solid-state laser medium 3 between the first resonator 11 and the second resonator 12, it is possible to emit Q-switch pulse laser light with a small pulse width, high peak power, and no jitter. (Ninth Embodiment)

[0107] The laser elements 1 to 1g according to the first to eighth embodiments may be arranged in an array. Fig. 15 is a plan view and a sectional view illustrating a plurality of laser elements 1h arranged in an array.

[0108] As in Fig. As illustrated in Figure 15, the laminated semiconductor layer 2 constituting the excitation light source 2 is divided into a plurality of laminated semiconductor regions 2a and 2b. One of the two adjacent laminated semiconductor regions 2a and 2b is used to emit the TM polarized beam, and the other is used to multiplex the TE polarized beam with the TM polarized beam. Thus, while excitation light is emitted from one mesa A of two light-emitting units corresponding to the two adjacent laminated semiconductor regions 2a and 2b, excitation light is hardly emitted from the other mesa B. Therefore, the light-emitting unit that emits the excitation light can be made larger.

[0109] As described above, according to the ninth embodiment, the plurality of laser elements 1h whose light outputs have been increased by providing the polarization splitting element 10 are arranged in the two-dimensional direction, so that it is possible to implement the laser elements 1h that can achieve a high light output and have a longer service life. (Tenth Embodiment)

[0110] It is also possible to construct a laser amplifying element using the structure of the laser element 1d or 1f described above in Fig. 10 or Fig. 12 to produce.

[0111] Fig. 16A is a sectional view of a laser gain element 50 according to the present disclosure and Fig. 16B is a perspective view of the laser gain element 50 according to the present disclosure. Further, Fig. 16C is a plan view schematically illustrating an optical path of laser light in the laser amplifying element 50.

[0112] The laser amplification element 50 in Fig. 16A to Fig. 16C includes an excitation light source 53 arranged on a support substrate 51 with a submount substrate 52 interposed therebetween, a polarization splitting element 60 arranged on the excitation light source 53, and a solid-state laser medium 54 arranged on the polarization splitting element 60 and not provided with the saturable absorber 4. The solid-state laser medium 54 is, for example, Yb:YAG. As described later, the excitation light source 53 and the solid-state laser medium 54 form a first resonator 55, and the light of the first wavelength λ1 is irradiated in an upper / lower direction (lamination direction) in Fig. 16A. More specifically, the first resonator 55 resonates the light of the first wavelength λ1 between the first reflection layer R1 (p-DBR72) in the excitation light source 53 and the second reflection layer R2 in the solid-state laser medium 54. Although the solid-state laser medium 3 in the laser element 1 is Fig. 1 comprises the third reflection layer R3 on the end face opposite the excitation light source 2 and the fourth reflection layer R4 on the end face opposite the saturable absorber 4, the solid-state laser medium 54 in Fig. 16A does not include the reflection layer on the end face opposite to the excitation light source 53 and includes the second reflection layer R2 on the end face on the side opposite to the reflection layer.

[0113] Furthermore, the laser amplification element 50 comprises Fig. 16A to Fig. 16C, the first reflection element 56 and the second reflection element 57 arranged along an opposite first side surface 54S1 and second side surface 54S2 of the solid-state laser medium 54, and the solid-state laser medium 54 serving as a gain medium 83 that causes the light of the second wavelength λ2 to reciprocate a plurality of times between the first reflection element 56 and the second reflection element 57.

[0114] The first reflection element 56 and the second reflection element 57 may comprise flat reflection mirrors or may have reflection mirrors with convex shapes in order to increase the light intensity in an amplification process and avoid damage to the materials.

[0115] Although the first reflection element 56 and the second reflection element 57 are arranged at a distance from the first side surface 54S1 and the second side surface 54S2 of the solid-state laser medium 54 in Fig. 16A, multilayer films formed by laminating at least one of a semiconductor material, a metal material, and a dielectric material on the first side surface 54S1 and the second side surface 54S2 may be formed, and these multilayer films may be used as the reflection mirrors.

[0116] Furthermore, the laser amplification element 50 comprises Fig. 16A to Fig. 16C, a light input unit IN provided along the first side surface 54S1 and a light output unit OUT provided along the second side surface 54S2. The light input unit IN inputs weak light (seed light) of the second wavelength λ2 into the first side surface 54S1. The light of the second wavelength λ2 reciprocates a plurality of times in the gain medium 83 and is emitted from the light output unit OUT.

[0117] Furthermore, the laser amplifying element 50 according to the present embodiment includes the polarization splitting element 60 similar to the polarization splitting element 10 according to the first to ninth embodiments. By providing the polarization splitting element 60, it is possible to increase the light output emitted by the polarization splitting element 10.

[0118] Furthermore, the laser amplification element 50 can be Fig. 16A to Fig. 16C, a cooling element 62 may be included. The cooling element 62 is disposed in the laser amplification element 50. The cooling element 62 is bonded to the side surfaces of the excitation light source 53, the polarization splitting element 60, and the solid-state laser medium 54, and dissipates heat generated by at least one of the excitation light source 53, the polarization splitting element 60, and the solid-state laser medium 54. The cooling element 62 is made, for example, of a metal material such as Cu, which has a high thermal conductivity. The cooling element 62 may be bonded to a housing (not shown) and dissipates heat from the cooling element 62 to the housing.

[0119] The carrier substrate 51 of the laser amplification element 50 in Fig. 16A to Fig. 16C, for example, is a Cu substrate, and the submount substrate 52 is disposed thereon. The submount substrate 52 is, for example, a laminated structure of a SiC layer 64 and an AuSn layer 65, and the p-electrodes 73 and n-electrodes 74 of the excitation light source 53 are electrically insulated from each other and bonded to the AuSn layer 65.

[0120] The excitation light source 53 is the laminated semiconductor layer 2 formed by laminating an n-type contact layer 67, an n-type DBR 68, a cladding layer 69, an active layer 70, a cladding layer 71, and a p-type DBR 72 in sequence on an n-GaAs substrate 66. P-type electrodes 73 and n-type electrodes 74 are alternately arranged on the p-type DBR 72. The p-type electrodes 73 conduct with the p-type DBR 72, and the n-type electrodes 74 conduct with the n-type DBR 68 via a via 75.

[0121] The laser gain element 50 according to the present disclosure includes the first resonator 55 similar to that shown in Fig. 1. The first resonator 55 resonates the light of the first wavelength λ1 between the first reflection layer R1 in the excitation light source 53 and the second reflection layer R2 in the solid-state laser medium 54. The first reflection layer R1 is the p-type DBR 72, and the second reflection layer R2 is arranged, for example, on the upper surface of a heat dissipation element 61. The heat dissipation element 61 can be omitted. The resonant operation of the light of the first wavelength λ1 performed by the first resonator 55 excites the solid-state laser medium 54. Fig. Figure 16A schematically illustrates the resonant operation of the first resonator 55 as a thin line. Amplified light (seed light) of the second wavelength λ2 is caused to be incident on the solid-state laser medium 54 in the excited state in a left direction from the right end in Fig. 16A. Thus, stimulated emission of the amplified light occurs, and the amplified light is subjected to laser amplification.

[0122] Furthermore, when Yb:YAG is used as the gain medium 83 and laser light whose wavelength is 1030 nm is used as the seed light, there is a problem that the laser light is absorbed in a region that is not excited in the gain medium 83 and cannot be sufficiently amplified. Therefore, when Yb:YAG is used as the gain medium 83, seed light that does not cause light absorption even in a non-excited state and whose wavelength is 1050 nm can be used. In this case, light absorption cannot occur even in the non-excited state, and therefore the wavelength of the seed light is not limited to 1050 nm.

[0123] As described above, by providing the solid-state laser medium 54 within the first resonator 55, it is possible to significantly simplify an optical configuration and achieve miniaturization.

[0124] Furthermore, according to the present disclosure, the size of the solid-state laser medium 54 in the laser amplification element 50 is not limited by the absorption length of the excitation light, so it is possible to increase the area of ​​the solid-state laser medium 54 regardless of the absorption length of the excitation light. By increasing the area of ​​the solid-state laser medium 54, it is possible to further improve the gain of the laser amplification element 50.

[0125] Furthermore, the excitation light source 53 formed by the laminated semiconductor layer 2 and the solid-state laser medium 54 can be integrally bonded, and the laser amplifying element 50 according to the present disclosure can be manufactured by a general-purpose semiconductor process, so that it is easy to achieve miniaturization and it is also possible to reduce manufacturing costs. < <anwendungsbeispiel>

[0126] The technology according to the present disclosure is widely applicable to medical imaging systems (hereinafter also referred to as electronic devices), distance measurement systems such as LiDAR (Light Detection and Ranging) devices, light sources for laser processing devices, and the like. Medical imaging systems are medical systems that use imaging technology, and include, for example, an endoscopic system and a microscopic system. [Endoscopic system]

[0127] An example of the endoscopic system is shown with reference to the Fig. 17 and Fig. 18 described. Fig. 17 is a diagram illustrating an example of a schematic configuration of an endoscopic system 5000 to which the technique according to the present disclosure is applicable. Fig. 18 is a diagram illustrating an example of configurations of an endoscope 5001 and a camera control unit (CCU) 5039. Fig. 17 illustrates a state in which a surgeon (doctor) 5067 involved in a surgical operation performs a surgical operation on a patient 5071 on a patient bed 5069 using the endoscopic system 5000. As shown in Fig. As illustrated in Fig. 17, the endoscopic system 5000 includes the endoscope 5001, which is the medical imaging device, the CCU 5039, a light source device 5043, a recording device 5053, an output device 5055, and a support device 5027 that supports the endoscope 5001.

[0128] In an endoscopic surgical procedure, an insertion aid tool called a trocar 5025 is punctured into the patient 5071. Further, an endoscope 5003 and a surgical instrument 5021 connected to the endoscope 5001 are inserted into the body of the patient 5071 through the trocar 5025. Examples of the surgical instrument 5021 include an energy treatment device such as an electric scalpel and forceps.

[0129] A surgical image, which is a medical image showing the inside of the body of the patient 5071 imaged through the endoscope 5001, is displayed on a display device 5041. The surgeon 5067 treats a surgical target using the surgical tool 5021 while viewing the surgical image displayed on the display device 5041. Note that the medical image is not limited to the surgical image and may also be a diagnostic image imaged during diagnosis. (Endoscope)

[0130] The endoscope 5001 is an imaging unit that images the inside of the body of the patient 5071, and is a camera 5005 that includes, for example, an optical condenser system 50051 that condenses incident light, an optical zoom system 50052 that changes a focal length of the imaging unit and enables optical zooming, an optical focus system 50053 that changes the focal length of the imaging unit and enables focus adjustment, and a light receiving element 50054, as shown in Fig. 18. The endoscope 5001 generates a pixel signal by condensing the light on the light-receiving element 50054 via the connected endoscope 5003 and outputs the pixel signal to the CCU 5039 via a transmission system. Note that the endoscope 5003 is an insertion part that includes an objective lens at the distal end and guides light from the connected light source device 5043 to the inside of the body of the patient 5071. The endoscope 5003 is, for example, a rigid endoscope in a case of a rigid mirror and a flexible endoscope in a case of a flexible mirror. The endoscope 5003 may be a forward-viewing endoscope or an oblique forward-viewing endoscope. Further, the pixel signal may be a signal based on a signal output from a pixel, and is, for example, a RAW signal or an image signal.Furthermore, a memory may be mounted on the transmission system connecting the endoscope 5001 and the CCU 5039, and the memory may be configured to store parameters related to the endoscope 5001 and the CCU 5039. The memory may be arranged, for example, at a connection portion or on a cable of the transmission system. For example, the memory of the transmission system stores parameters at the time of shipping the endoscope 5001 or parameters that change at the time of power distribution, and an operation of the endoscope can be changed based on the parameters read from the memory. Furthermore, a set of the endoscope and the transmission system may be referred to as an endoscope. The light-receiving element 50054 is a sensor that converts received light into a pixel signal and is, for example, a complementary metal-oxide-semiconductor (CMOS) type imaging element.The light-receiving element 50054 is preferably an imaging element that has a Bayer layout and is capable of color photography. Furthermore, the light-receiving element 50054 is preferably an imaging element that has a resolution of 4K (the number of horizontal pixels: 3840 × the number of vertical pixels: 2160), 8K (the number of horizontal pixels: 7680 × the number of vertical pixels: 4320), or square 4K (the number of horizontal pixels: 3840 or more × the number of vertical pixels: 3840 or more). The light-receiving element 50054 may be one sensor chip or may be a plurality of sensor chips. For example, a prism may be provided that splits incident light per predetermined wavelength band, and another light receiving element may be configured to image each wavelength band.Furthermore, a plurality of light-receiving elements for stereoscopic vision may be provided. Furthermore, the light-receiving element 50054 may be a sensor including an arithmetic processing circuit for image processing in a chip structure, and may be a time-of-flight (ToF) sensor. Note that the transmission system may be, for example, a fiber optic cable or wireless transmission. Wireless transmission only needs to enable the transmission of a pixel signal generated by the endoscope 5001. For example, the endoscope 5001 and the CCU 5039 may be wirelessly connected, or the endoscope 5001 and the CCU 5039 may be connected via a base station in an operating room. In this case, the endoscope 5001 may simultaneously transmit not only the pixel signal but also information (e.g., a processing priority of the pixel signal, a synchronization signal, or the like) related to the pixel signal.Note that a configuration may be used in which the endoscope is integrated with the endoscope and the camera, and the light receiving element is provided at a distal end part of the endoscope. [Camera Control Unit (CCU)]

[0131] The CCU 5039 is a control device that integrally controls the connected endoscope 5001 or the light source device 5043, and is, for example, an information processing device including an FPGA 50391, a CPU 50392, a RAM 50393, a ROM 50394, a GPU 50395, and an I / F 50396, as shown in Fig. 18. Further, the CCU 5039 can integrally control the connected display device 5041, the recording device 5053, and the output device 5055. For example, the CCU 5039 controls an irradiation timing, an irradiation intensity, and an irradiation light source type of the light source device 5043. Further, the CCU 5039 performs image processing such as development processing (e.g., demosaicing processing) or correction processing on a pixel signal output from the endoscope 5001, and outputs the processed pixel signal (e.g., image) to an external device such as the display device 5041. Further, the CCU 5039 transmits a control signal to the endoscope 5001 and controls the driving of the endoscope 5001. The control signal is, for example, information related to imaging conditions such as a magnification and a focal length of the imaging unit.Note that the CCU 5039 has an image down-conversion function and may be configured to simultaneously output a high-resolution (e.g., 4K) image to the display device 5041 and a low-resolution (e.g., HD) image to the recording device 5053.

[0132] Furthermore, the CCU 5039 may be connected to an external device (e.g., a recording device, a display device, an output device, or a support device) via an IP converter that converts a signal into a predetermined communication protocol (e.g., Internet Protocol (IP)). The connection of the IP converter and the external device may be configured through a wired network, or part or all of a network may be constructed as a wireless network. For example, the IP converter on a CCU 5039 side has a wireless communication function and can transmit a received video to an IP switch or an output-side IP converter via a wireless communication network such as the fifth-generation (5G) mobile communication system or the sixth-generation (6G) mobile communication system. [Light source device]

[0133] The light source device 5043 is a device that can emit light of 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 includes LED light sources each assigned to, for example, the three primary colors R, G, and B, and emits white light by controlling an output intensity or output timing of each light source. Further, the light source device 5043 may include a light source that can emit special light used for special light observation, in addition to a light source that emits normal light used for normal light observation.Special light is light of a predetermined wavelength band different from the normal light used for normal light observation, such as near-infrared light (light with a wavelength of 760 nm or more), infrared light, blue light, and ultraviolet light. Normal light is, for example, white light or green light. In narrow-band light observation, which is a type of special light observation, it is possible to image predetermined tissues such as blood vessels of a mucous membrane surface layer with high contrast by utilizing a wavelength dependence of light absorption in body tissues by alternately irradiating blue light and green light.Furthermore, in fluorescence observation, which is a type of special light observation, the surgeon can easily visually inspect body tissues or the like that are difficult for the surgeon to visually inspect using ordinary light by radiating excitation light to excite a drug injected into the body tissues, receiving fluorescence emitted by the drug that is affecting the body tissues or a target, and obtaining a fluorescence image. For example, in fluorescence observation using infrared light, it is possible to easily visually inspect the structure or an affected part of the body tissues by radiating infrared light having an excitation wavelength band onto a drug such as indocyanine green (ICG) injected into the body tissues and receiving the fluorescence of the drug. Furthermore, in fluorescence observation, a drug (e.g.,5-ALA), which is excited by special light in a blue wavelength band and emits fluorescence of a red wavelength band, may be used. Note that one type of irradiation light is set to the light source device 5043 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. At this time, information based on a pixel signal obtained by special light observation is preferably superimposed on a pixel signal obtained by normal light observation. Further, special light observation may be infrared light observation for radiating infrared light and observing the depth beyond an organ anterior surface, or multispectral observation using hyperspectral spectroscopy.Furthermore, photodynamic therapy can be used in combination. [Recording device]

[0134] The recording device 5053 is a device that records a pixel signal (e.g., image) acquired by the CCU 5039 and is, for example, a recorder. The recording device 5053 records the image acquired by the CCU 5039 on an HDD, an SDD, or an optical disk. The recording device 5053 can be connected to a network in a hospital and accessible from a device outside an operating room. Furthermore, the recording device 5053 can have an image downconversion or upconversion function. [Display device]

[0135] The display device 5041 is, for example, a device capable of displaying images, such as a display monitor. The display device 5041 displays a display image based on the pixel signal acquired by the CCU 5039. Note that the display device 5041 includes a camera and a microphone to function as an input device that enables line-of-sight recognition, voice recognition, and instruction input using a gesture. [Output device]

[0136] The output device 5055 is a device that outputs information acquired by the CCU 5039 and is, for example, a printer. The output device 5055 prints a print image on paper based on the pixel signal acquired by the CCU 5039. [Support device]

[0137] The support device 5027 is an articulated arm including a base part 5029 including an arm control device 5045, an arm part 5031 extending from the base part 5029, and a holding part 5032 attached to the distal end of the arm part 5031. The arm control device 5045 includes a processor such as a CPU and controls the driving of the arm part 5031 by operating according to a predetermined program. The support device 5027 controls parameters such as the length of each link 5035 constituting the arm part 5031 and a rotation angle and torque of each joint 5033 using the arm control device 5045 to control, for example, a position and posture of the endoscope 5001 held by the holding part 5032. Consequently, it is possible to change the endoscope 5001 to a desired position or posture, insert the endoscope 5003 into the patient 5071, and change an observation area in the body.The support device 5027 functions as an endoscope support arm that supports the endoscope 5001 during a surgical operation. Thus, the support device 5027 can play the role of an endoscope operator, who is an assistant who holds the endoscope 5001. Furthermore, the support device 5027 can be a device that supports a microscope device 5301 to be described later, and can also be referred to as a medical support arm. Note that the control of the support device 5027 can be an autonomous control scheme using the arm control device 5045, or a control scheme controlled by the arm control device 5045 based on user input.For example, the control scheme may be a master / slave scheme that controls the support device 5027, which is a slave device (replica device), such as a patient cart, based on the movement of a master device (primary device), which is a surgical console on the user's hand. Furthermore, the control of the support device 5027 may be capable of being remotely controlled from outside the operating room.

[0138] An example of the endoscopic system 5000 to which the technique according to the present disclosure is applicable has been described above. For example, the technique according to the present disclosure can be applied to the microscopic system. (Microscopic system)

[0139] Fig. 19 is a diagram illustrating an example of a schematic configuration of a microsurgical system to which the technique according to the present disclosure is applicable. Note that in the following description, the same components as those of the endoscopic system 5000 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0140] Fig. Fig. 19 schematically illustrates a state in which the surgeon 5067 performs a surgical procedure on the patient 5071 on the patient bed 5069 using the microsurgical system 5300. It should be noted that in Fig. 19, for the sake of simplicity, an illustration of a trolley 5037 of the configuration of the microsurgical system 5300 is omitted, and the microscope device 5301 is simplified and illustrated instead of the endoscope 5001. In this regard, the microscope device 5301 in the description may indicate a microscope unit 5303 provided at the distal end of the link 5035, or may indicate the entire configuration including the microscope unit 5303 and the support device 5027.

[0141] As in Fig. As illustrated in Figure 19, using the microsurgical system 5300, during a surgical procedure, an image of a part to be operated, imaged by the microscope device 5301, is displayed as an enlarged image on the display device 5041 installed in the operating room. The display device 5041 is installed facing the surgeon 5067. The surgeon 5067 performs various operations, such as resection of an affected part, on the part to be operated while observing a state of the part to be operated through a video shown on the display device 5041. The microsurgical system is used for, for example, eye surgery and brain surgery.

[0142] The example of the endoscopic system 5000 and the microsurgical system 5300 to which the technique according to the present disclosure is applicable has been described above. Note that systems to which the technique according to the present disclosure is applicable are not limited to such an example. For example, the support device 5027 may also support another observation device or another surgical tool instead of the endoscope 5001 or the microscope unit 5303 at the distal end. The other observation device may be, for example, forceps, tweezers, a pneumoperitoneum tube for pneumoperitoneum, or an energy treatment instrument for incising tissues and sealing a blood vessel by cauterization.The observation device and surgical instruments are supported by the support device, allowing the positions to be fixed with greater stability and reducing the workload of the medical personnel compared to manual support by the medical personnel. The technique according to the present disclosure can be applied to such a support device that supports configurations other than a microscope unit.

[0143] The technique according to the present disclosure can be suitably applied to the surgical tool 5021 in the above-described configuration. Specifically, by irradiating an affected part of a patient with a laser pulse of a short pulse from the laser element 1 according to the present embodiment, it is possible to treat the affected part more safely and reliably.

[0144] The present technique can also take the following configurations. (1) A laser element comprises: a laminated semiconductor layer comprising a first reflection layer used for light of a first wavelength and an active layer performing surface light emission at the first wavelength; a second reflection layer disposed closer to a light-emitting surface side than the laminated semiconductor layer and used for the light of the first wavelength; and a polarization splitting element that individually resonates and multiplexes each of the orthogonally polarized rays contained in the light emitted from the laminated semiconductor layer between the first reflection layer and the second reflection layer. (2) In the laser element described in (1), the laminated semiconductor layer comprises a plurality of laminated semiconductor regions associated with the orthogonally polarized beams, and the polarization splitting element resonates and multiplexes a corresponding polarized beam between the first reflection layer and the second reflection layer for each of the plurality of laminated semiconductor regions individually. (3) In the laser element described in (1) or (2), the polarization splitting element includes a first surface in contact with a light emitting surface of the laminated semiconductor layer, and a second surface disposed on an opposite side to the first surface and between the first reflection layer and the second reflection layer. (4) In the laser element described in any one of (1) to (3), the orthogonally polarized beams comprise orthogonally polarized beams of different wavelengths, wherein the polarization splitting element individually resonates and multiplexes each of the orthogonally polarized beams comprising the orthogonally polarized beams of the different wavelengths between the first reflection layer and the second reflection layer. (5) In the laser element described in (4), the orthogonally polarized beams include a transverse magnetic (TM) polarized beam and a transverse electric (TE) polarized beam, wherein the polarization splitting element individually resonates and multiplexes each of the TE polarized beam and the TM polarized beam between the first reflection layer and the second reflection layer. (6) In the laser element described in (5), the polarization splitting element multiplexes the TE polarized beam with the TM polarized beam within the polarization splitting element. (7) In the laser element described in any one of (1) to (6), the polarization splitting element comprises a laminated body obtained by alternately laminating a plurality of polarization splitting films and a plurality of reflection films with a distance from each other, the laminated body has a cross-sectional area obtained by cutting the laminated body in a direction of 45 degrees in a normal direction of a lamination surface, and the polarization splitting element is arranged so that the normal direction of the cross-sectional area is parallel to a normal direction of the laminated semiconductor layer. (8) In the laser element described in any one of (1) to (6), the polarization splitting element comprises a birefringent material for splitting the light emitted from the laminated semiconductor layer into the orthogonally polarized rays. (9) The laser element described in any one of (1) to (8) further comprises a laser medium that is arranged closer to the light emission surface side than the polarization splitting element and oscillates at a second wavelength different from the first wavelength. (10) The laser element described in (9) comprises: a third reflection layer disposed on a first end face of the laser medium on one side of the polarization splitting element and used for light of the second wavelength; and a fourth reflection layer disposed on a second end face of the laser medium on a side opposite to the first end face and used for the light of the second wavelength. (11) In the laser element described in (10), the third reflection layer is arranged closer to the light emission surface side than the second reflection layer. (12) In the laser element described in (10), the third reflection layer is arranged between the polarization splitting element and the second reflection layer. (13) In the laser element described in (12), the third reflection layer is in contact with an end surface of the polarization splitting element. (14) In the laser element described in any one of (10) to (13), the fourth reflection layer is in contact with the second reflection layer or is arranged closer to the light emission surface side than the second reflection layer. (15) The laser element described in (9) further comprises a saturable absorber arranged closer to the light-emitting surface side than the laser medium. (16) The laser element described in (15) further comprises: a third reflection layer disposed on an end face of the laser medium on a side opposite to the polarization splitting element and used for light of the second wavelength; and a fourth reflection layer arranged on the light-emitting surface side of the saturable absorber and used for the light of the second wavelength. (17) In the laser element described in (16), the third reflection layer is arranged closer to the light emission surface side than the second reflection layer. (18) In the laser element described in (16), the second reflection layer is arranged between the third reflection layer and the fourth reflection layer. (19) In the laser element described in any one of (15) to (18), each of the laminated semiconductor layer, the polarization splitting element, the laser medium, and the saturable absorber is divided into a plurality of regions arranged at a predetermined pitch in association with a plurality of light-emitting units that emit pulse laser light of the second wavelength. (20) An imaging device comprises: a laser element; and a control unit that performs control to emit light from the laser element, and the laser element includes: a laminated semiconductor layer comprising a first reflection layer used for light of a first wavelength and an active layer performing surface light emission at the first wavelength, a second reflection layer arranged closer to a light-emitting surface side than the laminated semiconductor layer and used for the light of the first wavelength, and a polarization splitting element that individually resonates and multiplexes each of a plurality of polarized rays included in the light emitted from the laminated semiconductor layer between the first reflection layer and the second reflection layer.

[0145] Aspects of the present disclosure are not limited to the above-mentioned individual embodiments and include various modifications that can be achieved by those skilled in the art, and the effects of the present disclosure are also not limited to the details described above. In other words, various additions, modifications, and partial deletions can be made without departing from the conceptual spirit and gist of the present disclosure, which can be derived from the details defined in the claims and the equivalents thereof. [List of reference symbols] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h laser element 2 Excitation light source (laminated semiconductor layer) 2a First laminated semiconductor region 2b Second laminated semiconductor region 3 Solid-state laser medium 4 Saturable absorber 5 n-GaAs substrate 6 Sheath layer 7 Active layer 8 Sheath layer 10 Polarization splitting element 11 First resonator 12 Second resonator 13 First optical element 14 Second optical element 15 material layers 16 Polarization splitting film 17 Reflection film 17a First reflection film 17b Second reflection film 20 light emission unit 21 Base material layer 22 First substrate 23 Base material layer 24 Second substrate 25 Laminated body 31 Pre-oxidation layer 32 Post-oxidation layer (e.g. Al2O3 layer) 33 Contact layer 34 Insulating film 35 Conductive material 50 laser amplification element 51 Carrier substrate 52 submount substrate 53 Excitation light source 54 Solid-state laser medium 55 First Resonator 56 First reflection element 57 Second reflection element 60 polarization splitting element 61 Heat dissipation element 62 cooling element 64 SiC layer 65 AuSn layer 66 n-GaAs substrate 67 Contact layer 69 Mantle layer 70 active layer 71 Mantle layer 73 p-electrode 74 n-electrode 75 Via 83 Gain medium 100 laser elements QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2021 / 106757 A1

[0003] < / anwendungsbeispiel>

Claims

[1] Laser element, comprising: a laminated semiconductor layer comprising a first reflection layer used for light of a first wavelength and an active layer performing surface light emission at the first wavelength; a second reflection layer disposed closer to a light-emitting surface side than the laminated semiconductor layer and used for the light of the first wavelength; and a polarization splitting element that individually resonates and multiplexes each of the orthogonally polarized rays contained in the light emitted from the laminated semiconductor layer between the first reflection layer and the second reflection layer. [2] The laser element according to claim 1, wherein the laminated semiconductor layer comprises a plurality of laminated semiconductor regions associated with the orthogonally polarized beam, and the polarization splitting element resonates and multiplexes a corresponding polarized beam between the first reflection layer and the second reflection layer for each of the plurality of laminated semiconductor regions individually. [3] The laser element according to claim 1, wherein the polarization splitting element comprises a first surface in contact with a light emitting surface of the laminated semiconductor layer, and a second surface disposed on an opposite side to the first surface and between the first reflection layer and the second reflection layer. [4] Laser element according to claim 1, wherein the orthogonally polarized rays comprise orthogonally polarized rays of different wavelengths, and the polarization splitting element individually resonates and multiplexes each of the orthogonally polarized beams comprising the orthogonally polarized beams of different wavelengths between the first reflection layer and the second reflection layer. [5] Laser element according to claim 4, wherein the orthogonally polarized beams comprise a transversely magnetic (TM) polarized beam and a transversely electric (TE) polarized beam, and the polarization splitting element individually resonates and multiplexes each of the TE polarized beam and the TM polarized beam between the first reflection layer and the second reflection layer. [6] The laser element according to claim 5, wherein the polarization splitting element multiplexes the TE polarized beam with the TM polarized beam within the polarization splitting element. [7] Laser element according to claim 1, wherein the polarization splitting element comprises a laminated body obtained by alternately laminating a plurality of polarization splitting films and a plurality of reflection films at a distance from each other, the laminated body has a cross-sectional area obtained by cutting the laminated body in a direction of 45 degrees in a normal direction of a lamination surface, and the polarization splitting element is arranged such that the normal direction of the cross-sectional area is parallel to a normal direction of the laminated semiconductor layer. [8] The laser element according to claim 1, wherein the polarization splitting element comprises a birefringent material for splitting the light emitted from the laminated semiconductor layer into the orthogonally polarized beams. [9] The laser element according to claim 1, further comprising a laser medium disposed closer to the light emission surface side than the polarization splitting element and oscillating at a second wavelength different from the first wavelength. [10] Laser element according to claim 9, further comprising: a third reflection layer disposed on a first end face of the laser medium on one side of the polarization splitting element and used for light of the second wavelength; and a fourth reflection layer disposed on a second end face of the laser medium on a side opposite to the first end face and used for the light of the second wavelength. [11] The laser element according to claim 10, wherein the third reflection layer is arranged closer to the light emission surface side than the second reflection layer. [12] The laser element according to claim 10, wherein the third reflection layer is disposed between the polarization splitting element and the second reflection layer. [13] The laser element according to claim 12, wherein the third reflection layer is in contact with an end surface of the polarization splitting element. [14] The laser element according to claim 10, wherein the fourth reflection layer is in contact with the second reflection layer or is arranged closer to the light emission surface side than the second reflection layer. [15] The laser element according to claim 9, further comprising a saturable absorber arranged closer to the light emission surface side than the laser medium. [16] Laser element according to claim 15, further comprising: a third reflection layer disposed on an end surface of the laser medium on a side opposite to the polarization splitting element and used for light of the second wavelength; and a fourth reflection layer disposed on the light-emitting surface side of the saturable absorber and used for the light of the second wavelength. [17] The laser element according to claim 16, wherein the third reflection layer is arranged closer to the light emission surface side than the second reflection layer. [18] The laser element according to claim 16, wherein the second reflection layer is disposed between the third reflection layer and the fourth reflection layer. [19] A laser element according to claim 15, wherein each of the laminated semiconductor layer, the polarization splitting element, the laser medium and the saturable absorber is divided into a plurality of regions arranged at a predetermined interval in association with a plurality of light-emitting units that emit pulse laser light of the second wavelength. [20] Electronic device comprising: a laser element; and a control unit that performs control to emit light from the laser element, wherein the laser element includes: a laminated semiconductor layer comprising a first reflection layer used for light of a first wavelength and an active layer performing surface light emission at the first wavelength, a second reflection layer arranged closer to a light-emitting surface side than the laminated semiconductor layer and used for the light of the first wavelength, and a polarization splitting element that individually resonates and multiplexes each of the orthogonally polarized rays contained in the light emitted from the laminated semiconductor layer between the first reflection layer and the second reflection layer.

Images