JP2006242817A - Semiconductor laser gyroscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser gyroscope capable of precisely and simply detecting rotation by using a semiconductor of novel structure. <P>SOLUTION: The semiconductor laser gyroscope comprises: the semiconductor laser 10 for emitting the first and the second laser beams; the photo detector 72 for detecting the rotation; the photodiode 77 for monitoring wave length; the Fabry Perot etalon 76; and the wave length control means. The semiconductor laser 10 includes the active layers provided with the opposite first and second end faces. The first laser beam is a part of circulating laser light (L1) on the rhombic path in the active layer emitted from the first terminal face, and the 2nd laser beam is a part of circulating laser light (L2) circulating in reverse direction in the rhombic path emitted from the first terminal face. The laser beam emitted from the second terminal face is monitored by the photodiode 77 through the Fabry Perot etalon 76, the wave length of the laser beam is stabilized based on the output. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gyro using a semiconductor laser.

  Among the gyros for detecting the angular velocity of the rotating object, the optical gyro has a feature of high accuracy. In the optical gyro, the angular velocity is detected using a frequency difference between two laser beams traveling in opposite directions along an annular optical path. As such an optical gyro, an optical gyro using a rare gas laser has been proposed (see, for example, Patent Document 1). In these optical gyros, laser beams that circulate in the opposite directions on the same path are extracted to form interference fringes. A general configuration of these optical gyros is shown in FIG. In the optical gyro of FIG. 17, the interference fringes are expressed by the following formula (1).

Here, I ₀ is the light intensity of the laser light, and λ is the wavelength of the laser light. Further, ε is an angle shown in FIG. 17, and χ is a coordinate in the X direction shown in FIG. Δω is a frequency difference between a clockwise mode and a counterclockwise mode when the gyro is rotated, and t is a time. Δω is proportional to the angular velocity Ω of the gyro rotation. That is, Δω = 4 AΩ / (Lλ). Here, A is an area surrounded by a ring shape, and L is an optical path length. φ indicates the initial phase difference between the two laser beams. In this gyro, the rotational speed and direction of the gyro are detected by detecting the movement speed and direction of the interference fringes. However, an optical gyro using a rare gas laser has a problem that a high voltage is required for driving and power consumption is large, and a problem that the apparatus is large and weak against heat.

As a gyro for solving such a problem, a gyro using a semiconductor ring laser having an annular (triangular or square) waveguide has been proposed (for example, see Patent Document 2). The semiconductor laser used in this gyro has an annular waveguide having a substantially constant width. Then, two laser beams that circulate in the opposite directions in the annular waveguide are extracted to detect the interference fringes. However, since the laser light confined using a thin waveguide spreads greatly when emitted to the outside of the waveguide, it is difficult to actually detect the interference fringes with high accuracy. Therefore, in a gyro using a semiconductor laser, a gyro for detecting a beat frequency corresponding to a frequency difference between two laser beams from a voltage change between two electrodes of the semiconductor laser (see, for example, Patent Document 3), or an end face of a resonator A gyro (see, for example, Patent Document 4) that detects beat frequency using evanescent light that oozes out is generally used.
Japanese Patent Laid-Open No. 11-351881 JP 2000-230831 A JP-A-4-174317 JP 2000-121367 A

  However, a gyro that detects the beat frequency requires a special device for detecting the rotational direction.

  Further, the semiconductor laser gyro has a problem that the detected angular velocity changes when the frequency of light emitted from the semiconductor laser changes due to a change with time, a temperature change, or the like. For example, considering that the oscillation wavelength of the semiconductor laser is 850 nm and rotation of 180 ° / second is detected, the detected angular velocity is shifted by 0.21 ° / second when the wavelength is shifted by 1 nm. In order to suppress such detection errors, it is necessary to stabilize the wavelength of the laser light emitted from the semiconductor laser.

  In view of such circumstances, an object of the present invention is to provide a semiconductor laser gyro that can detect rotation more accurately and easily than a conventional gyro using a semiconductor laser by using a semiconductor laser having a novel structure. One.

  The present inventors have found that a special laser beam can be excited by a semiconductor laser having a special structure. In this semiconductor laser, two laser beams traveling in opposite directions along the rhombus path are excited. These two laser beams are emitted from the semiconductor laser to the outside in a well-collimated state, and form clear interference fringes. The present invention is based on this new knowledge.

  The semiconductor laser gyro of the present invention includes a substrate, a semiconductor laser disposed on the substrate and emitting first and second laser beams, a first photodetector for rotation detection, and a second wavelength monitor. And a Fabry-Perot etalon, and a wavelength control means for controlling the wavelengths of the first and second laser beams, wherein the first photodetector is the first photodetector. And the second laser beam is disposed at a position where an interference fringe is formed, the semiconductor laser includes an active layer having first and second end faces facing each other, and the first laser beam is A part of the laser beam (L1) that circulates on the rhombic path in the active layer is a laser beam emitted from the first end surface, and the second laser beam is the laser beam ( L1) orbiting in the opposite direction A part of the laser beam (L2) is a laser beam emitted from the first end surface, and is selected from the laser beam (L1) and the laser beam (L2) emitted from the second end surface At least one laser beam is monitored by the second photodetector via the Fabry-Perot etalon, and the first and second lasers are controlled by the wavelength control unit based on the output of the second photodetector. Stabilize the wavelength of light.

  According to the present invention, a highly accurate and small semiconductor laser gyro can be realized. In the gyro of the present invention, a semiconductor laser having a special structure is used, and from this semiconductor laser, two laser beams traveling in opposite directions along an annular path are emitted in a well-collimated state. Further, in this semiconductor laser, the deterioration of the laser beam at the emission end face is small. Therefore, clear interference fringes are formed by the two laser beams, and the rotational speed (angular speed) can be detected with high accuracy. Further, according to the gyro of the present invention, the rotation speed and the rotation direction can be easily calculated by observing the movement of the interference fringes with two or more light receiving elements. For these detections, a circuit similar to a circuit used in a conventional optical gyro using a rare gas laser can be applied. Therefore, the gyro of the present invention can be easily applied to various devices.

  In addition, the semiconductor laser gyro of the present invention detects the wavelength change using a Fabry-Perot etalon and stabilizes the wavelength by controlling to cancel the detected wavelength change, so that the rotation can be detected with higher accuracy.

  Hereinafter, embodiments of the present invention will be described. A semiconductor laser gyro (semiconductor laser gyro element) described below is an example of the present invention, and the present invention is not limited to the following description. Moreover, in the following description, the same code | symbol may be attached | subjected to the same part and the overlapping description may be abbreviate | omitted.

  The semiconductor laser gyro of the present invention includes a substrate, a semiconductor laser disposed on the substrate and emitting first and second laser beams, a first photodetector for rotation detection, and a second wavelength monitor. A photodetector; a Fabry-Perot etalon; and wavelength control means for controlling wavelengths of the first and second laser beams. The first photodetector is disposed at a position where an interference fringe is formed by the first and second laser beams. The semiconductor laser includes an active layer having first and second opposing end faces. The first laser beam is a laser beam in which a part of the laser beam (L1) that circulates on the rhombic path in the active layer is emitted from the first end face, and the second laser beam is on the path. Part of the laser light (L2) that circulates in the direction opposite to the laser light (L1) is the laser light emitted from the first end face. At least one laser beam selected from the laser beam (L1) and the laser beam (L2) emitted from the second end face is monitored by the second photodetector via a Fabry-Perot etalon, and the second light beam Based on the output of the detector, the wavelength control means stabilizes the wavelengths of the first and second laser beams.

  Although the wavelength of laser light emitted from a semiconductor laser changes depending on temperature or the like, in the present invention, a change in wavelength is detected using a Fabry-Perot etalon, and the wavelength is stabilized based on the result. Therefore, according to the gyro of the present invention, rotation can be detected more accurately. The wavelength is stabilized by controlling the magnitude of current injected into the active layer and the substrate temperature. These stabilizations have the same influence on both the first and second laser beams, and thus do not adversely affect the detection of the frequency difference between the first and second laser beams due to rotation.

  The wavelength control means includes a device that controls the substrate temperature and the injection current based on the output of the second photodetector. A known device can be applied to such a device. For example, the substrate temperature can be controlled using a Peltier element or the like.

  The gyro may further include a third photodetector for monitoring the amount of the at least one laser beam emitted from the second end surface. In this case, the wavelengths of the first and second laser beams can be stabilized by the wavelength control means based on the output of the second photodetector and the output of the third photodetector.

  The planar shape of the active layer is a shape that encloses the rhombus so that the corner of the rhombus path is located at the outer edge. When current is injected into the active layer, light is generated. This light is reflected by the end face of the active layer and causes stimulated emission. Then, laser light (L1 and L2) that circulates a specific path stably is excited according to the planar shape of the active layer. That is, the active layer functions as a resonator (cavity). The end face of the active layer that functions as a resonator is formed so that the generated light circulates in a predetermined path. In order to excite the laser light that goes around the rhombus path, end faces (side surfaces) are formed in the active layer at positions corresponding to the four corners of the path (virtual rhombus). The active layer and the clad layer disposed so as to sandwich the active layer are usually uniform layers, and a waveguide having a certain width corresponding to the above-described path is not formed. The shape of the rhombic path can be changed depending on the shape of the active layer.

(Semiconductor laser)
First, a semiconductor laser used in the gyro of the present invention will be described.

  The active layer of the semiconductor laser preferably has a planar shape that is not a polygonal ring. Since the laser light confined in a thin waveguide having a polygonal ring shape such as a triangular ring shape or a quadrangular ring shape is spread when emitted, a clear interference fringe is not formed. Therefore, the planar shape of the active layer is preferably not substantially polygonal. In the semiconductor laser used in the present invention, by injecting carriers into the active layer, a laser beam of a specific mode having an active layer extending in a two-dimensional direction as a resonator, specifically, a laser that circulates in the active layer Light can be obtained. Laser light emitted from such an active layer is well collimated, and the half-value width of the laser light intensity can be set to 10 ° or less (for example, 5 ° or less). Even when the through hole is formed near the center of the active layer, it may be an active layer that is not substantially polygonal, that is, an active layer in which a waveguide having a substantially constant width is not formed in an annular shape. In this specification, the “planar shape” means a shape shown in FIG. 3, that is, a shape perpendicular to the stacking direction of the semiconductor layers.

  In the semiconductor laser used in the present invention, the first corner and the second corner facing each other in the rhombic path are disposed on the first end face and the second end face, respectively. It is preferable that a diagonal line connecting the corner portion and the second corner portion is not parallel to the first and second laser beams.

  The semiconductor laser used in the present invention includes first and second electrodes for injecting current into the active layer. It is preferable that at least one electrode selected from the first and second electrodes and a semiconductor layer constituting the semiconductor laser are in contact with each other along the rhombic path. Current is injected through the contact area. According to this configuration, carriers can be injected into the rhomboid path portion of the active layer, and two laser beams (L1 and L2) that circulate on the rhombus path are easily excited. In a typical example, the at least one electrode is in contact with the semiconductor layer so as to substantially correspond to a diamond-shaped path (diamond-shaped path). In these cases, the at least one electrode and the semiconductor layer may be in annular contact. In this specification, the phrase “so as to substantially correspond to the rhombus route” means 50% or more (preferably 70% or more) of the rhombus route in addition to the case of completely corresponding to the rhombus route. And more preferably 90% or more). In addition, the area of the region corresponding to the rhombus path is usually 50% or less, for example, 30% or less, with respect to the area of the planar shape of the active layer.

  At least one electrode selected from the first and second electrodes may include a first portion that injects a current that generates a gain, and a second portion that injects less current than the first portion. . In the first part, a current necessary for laser oscillation is injected. By injecting a weak current into the second portion so as not to generate a gain, the laser light traveling in a direction other than the rhombus optical path can be attenuated.

  The first to fourth end faces of the active layer exist so as to correspond to the first to fourth corners of the rhombic path. The active layer preferably satisfies the condition that the laser beam (L1) and the laser beam (L2) are totally reflected at the third and fourth end faces. By totally reflecting the laser beam at the third and fourth end faces, the laser oscillation threshold can be lowered.

  The preferred shape of the rhombus path varies depending on the wavelength of the laser light and the material of the active layer, but the distance between the first corner and the second corner (the length of the longer diagonal of the rhombus), the third The ratio of the distance connecting the corners of the second and the fourth corners (the length of the shorter diagonal of the rhombus) is, for example, in the range of 600: 190 to 600: 30. Although the first end surface is a mirror surface, mirror coating treatment or the like is usually not performed so that a part of the laser light circulating in the active layer is emitted to the outside. Note that the first end face may be processed so that the laser light is easily emitted to the outside.

  The first end surface of the active layer is preferably a curved surface. In particular, it is preferable that each of the first and second end surfaces is an outwardly convex curved surface. According to this configuration, it is possible to stably generate the laser light that goes around the rhombus path, and to stably emit the first and second laser lights from the first end face. Each of the two outwardly convex curved surfaces is preferably a part of a cylinder having a center on a diagonal line connecting the first and second corners of the rhombus path.

  The radius of the cylinder described above, that is, the curvature radius R1 of the first end face and the curvature radius R2 of the second end face are both in the vicinity of half of the distance L between the first corner and the second corner. Or a distance L or more. The upper limit of R1 and R2 is not particularly limited, but is, for example, twice or less the distance L.

  The active layer preferably includes a first region including a rhombic path and a second region adjacent to the first region. In this case, the planar shape of the first region is preferably a substantially rectangular shape, and more specifically, a shape in which the short side of the rectangle is a curved surface convex outward. In this configuration, laser light that travels along the rhombic optical path using the first region as a resonator is excited. Further, according to this configuration, the laser light traveling in a direction other than the rhombus path can be attenuated by the second region.

  The planar shape of the active layer constituted by the first region and the second region is preferably substantially H-shaped (more specifically, a shape obtained by extending H laterally) (see FIG. 3). In this case, four second regions are adjacent to the first region. In this case, the length Ls (μm) of the second region in the direction parallel to the diagonal line connecting the first corner and the second corner, and the distance between the first corner and the second corner L (μm) preferably satisfies L / 4 <Ls. Also, the length Ws (see FIG. 3) of the second region in the direction parallel to the diagonal line connecting the third corner and the fourth corner is, for example, the third corner and the fourth corner. 1 to 3 times the distance W connecting the two.

  There is no particular limitation on the semiconductor and the laminated structure that constitute the semiconductor laser of the present invention, and the semiconductor laser is selected according to the wavelength of the laser beam to be used. The wavelength of the laser light (L1 and L2) is not particularly limited, but the shorter angular wavelength can detect the angular velocity of rotation with higher accuracy. A preferable wavelength is 1550 nm or less, and particularly preferably 900 nm or less. An example of the material of the semiconductor layer is, for example, a III-V compound semiconductor.

  Hereinafter, a preferred example of the semiconductor laser used in the present invention will be described. A perspective view of an example of a semiconductor laser is shown in FIG. 1, and a cross-sectional view taken along line II in FIG. 1 is shown in FIG. Note that the drawings used for explaining the present invention are schematic, and the scale of each part is changed for easy understanding.

  1 includes a substrate 11, a semiconductor layer 20 formed on the substrate 11, an insulating layer 12 and a first electrode 13 formed on the semiconductor layer 20, and the entire back surface of the substrate 11. And a second electrode 14 formed on the substrate.

  Referring to FIG. 2, the semiconductor layer 20 is laminated in order from the substrate 11 side, the buffer layer 21, the buffer layer 22, the graded layer 23, the clad layer 24, the graded layer 25, the active layer 26, and the graded layer. 27, a clad layer 28 and a cap layer 29. On the cap layer 29, the patterned insulating layer 12 is formed. A first electrode 13 is formed on the insulating layer 12. Since the insulating layer 12 has a through hole, the first electrode 13 and the cap layer 29 are in contact with each other in the region 31 in which the through hole is formed.

  3 and 4 show planar shapes when the active layer 26 of the semiconductor laser 10 is viewed from above. In FIG. 4, a portion of a region 31 where the first electrode 13 and the semiconductor layer 20 (cap layer 29) are in contact with each other is indicated by hatching. The semiconductor layer 20 has the same planar shape as the active layer 26.

  Referring to FIG. 3, the active layer 26 is a thin film formed in a planar shape including a rhombic path 32. Of the first to fourth corners 32a to 32d of the path 32, the first and second corners 32a and 32b are smaller in angle than the third and fourth corners 32c and 32d. The active layer 26 has first to fourth end surfaces (mirror surfaces) 26a to 26d arranged so as to include corner portions 32a to 32d. The first end surface 26a and the second end surface 26b are opposed to each other, and are curved surfaces that protrude outward. The third and fourth end faces 26c and 26d are flat planes.

  The active layer 26 includes a first region 26f and four second regions 26s adjacent to the first region. The planar shape of the first region 26f is a shape in which the short side of the rectangle is a curved surface protruding outward. The path 32 is formed in the first region 26f. The active layer 26 constituted by the first region 26f and the second region 26s has a substantially H-shape (more specifically, a shape obtained by horizontally extending the H-shape).

  With reference to FIG. 4, a region 31 in which the first electrode 13 and the semiconductor layer 20 are in contact is formed in a substantially diamond shape so as to correspond to the path 32. The reason why the region 31 does not completely correspond to the path 32 is that when the through hole is formed in the insulating layer 12, there is a limitation in the manufacturing process. Although it is possible to form the region 31 in a diamond shape by a known method so as to completely correspond to the path 32, the manufacturing process becomes complicated.

  When a voltage is applied between the first electrode 13 and the second electrode 14 to inject carriers into the active layer 26, light is emitted from the active layer 26. Since this light is confined by the graded layers 25 and 27, it moves in the active layer 26. Among such lights, the light traveling on the path 32 causes stimulated emission while being reflected by the end faces 26a to 26d. For this reason, the laser beam L1 which goes around the path 32 as an optical path is generated. Similarly, a laser beam L2 that circulates in a direction opposite to the laser beam L1 using the path 32 as an optical path is generated. A part of the laser beams L1 and L2 is emitted from the first corner portion 32a of the first end face 26a and becomes the first and second laser beams 35 and 36 (see FIG. 4).

  The distance L (see FIG. 3) between the first corner 32a and the second corner 32b is 600 μm, and the distance W between the third corner 32c and the fourth corner 32d is 60 μm. It is. In the semiconductor laser 10, the laser beams (L1 and L2) are totally reflected at the end faces 26c and 26d.

  The four second regions 26s are formed in order to suppress a mode generated by the multiple reflection of the laser light generated in the first region 26f on the end surfaces 26c and 26d. In the semiconductor laser 10, the length Ls (see FIG. 3) of the second region 26s in the direction parallel to the diagonal line 32ab connecting the first corner portion 32a and the second corner portion 32b is 160 μm. On the other hand, L / 4 is 150 μm, and since L / 4 <Ls is satisfied, the above mode is particularly suppressed. The length Ws of the second region 26s in the direction of the diagonal line 32cd connecting the third corner portion 32c and the fourth corner portion 32d is 70 μm.

  The shapes of the end surfaces 26a and 26b are each a partial shape of a cylindrical curved surface. Specifically, it has the same shape as a part of a curved surface of a cylinder on the diagonal line 32ab and having a central axis perpendicular to the surface of the active layer 26. The radius of the cylinder, that is, the radius of curvature R1 (see FIG. 3) of the end face 26a is 600 μm, and the radius of curvature R2 (not shown) of the end face 26b is also 600 μm. The planar shape of the active layer 26 is symmetrical with respect to the diagonal line 32ab and the diagonal line 32cd, and the planar shape of the end face 26b is with respect to the diagonal line 32cd connecting the third corner part 32c and the fourth corner part 32d. It is symmetrical with the planar shape of the end face 26a. However, they do not have to be line symmetrical.

  Table 1 shows materials and film thicknesses of the substrate 11, the semiconductor layer 20, the insulating layer 12, the first electrode 13, and the second electrode 14. In Table 1, for some semiconductor layers, the band gap Eg, majority carriers and their concentrations are also shown.

  In addition, each layer which comprises the 1st electrode 13 and the 2nd electrode 14 may be alloyed by heat processing. Moreover, the structure shown in Table 1 is an example, and is suitably changed according to the characteristic calculated | required by the semiconductor laser.

  The buffer layers 21 and 22 and the graded layer 23 are formed in order to obtain a high-quality III-V compound semiconductor crystal.

  The aluminum composition ratio X of the graded layer 23 gradually increases from the buffer layer 22 side toward the cladding layer 24 side. Specifically, the composition ratio X is 0.2 at the interface with the buffer layer 22 and 0.5 at the interface with the cladding layer 24.

In the graded layer 25, the concentration of Si as a dopant gradually decreases from the cladding layer 24 side toward the active layer 26 side. Specifically, it is about 1 × 10 ¹⁸ cm ⁻³ at the interface with the cladding layer 24 and about 1 × 10 ¹⁷ cm ⁻³ at the interface with the active layer 26. Further, the aluminum composition ratio X of the graded layer 25 also decreases in a parabolic shape from the cladding layer 24 side toward the active layer 26 side. Specifically, the composition ratio X is 0.5 at the interface with the cladding layer 24 and 0.2 at the interface with the active layer 26.

In the graded layer 27, the concentration of Be as a dopant gradually increases from the active layer 26 side toward the cladding layer 28 side. Specifically, it is about 1 × 10 ¹⁷ cm ⁻³ at the interface with the active layer 26 and about 1 × 10 ¹⁸ cm ⁻³ at the interface with the cladding layer 28. Further, the Al composition ratio X of the graded layer 27 also increases in a parabolic shape from the active layer 26 side toward the cladding layer 28 side. Specifically, the composition ratio X is 0.2 at the interface with the active layer 26 and 0.5 at the interface with the cladding layer 28.

  A band gap profile of the semiconductor layer 20 is schematically shown in FIG. The band gap of the graded layer 25 decreases in a parabolic manner from 2.0 eV to 1.7 eV from the cladding layer 24 toward the active layer 26 side. The band gap of the graded layer 27 increases in a parabolic manner from 1.7 eV to 2.0 eV from the active layer 26 toward the cladding layer 28 side.

  The semiconductor laser 10 is a so-called single quantum well type laser. Carriers injected from two electrodes are confined in the active layer 26 and laser oscillation is started with a low threshold current. The active layer 26 may have other forms such as a multiple quantum well type.

  FIG. 6 schematically shows changes in the refractive index from the cladding layer 24 to the cladding layer 28. The clad layer 24, the graded layer 25, the graded layer 27, and the clad layer 28 are made of a material having a refractive index lower than that of the active layer 26 in order to confine light in the active layer 26. Since the refractive index of the active layer 26 is the highest, the light generated in the active layer 26 is confined in the active layer 26 and the vicinity thereof.

  The first electrode 13 of the semiconductor laser 10 may include a first portion that injects a current that generates a gain, and a second portion that injects a smaller current than the first portion.

  In the semiconductor laser 10, single mode oscillation starts when the injected current exceeds the threshold current. As the injected current further increases from the threshold current, the oscillation mode changes in the order of single mode, twin mode, and rocking mode. In the single mode, as shown in FIG. 4, the first and second laser beams 35 and 36 are emitted. In the twin mode, two laser beams are periodically and alternately emitted. In the rocking mode, only one of the two laser beams is emitted. Therefore, in the present invention, the semiconductor laser 10 is normally operated in a single mode. Specifically, for example, the laser may be oscillated by passing a current of 200 mA between the first electrode 13 and the fourth electrode 14. Note that the gyro of the present invention may be provided with a special function by utilizing the fact that the oscillation mode can be changed by the injected current.

(Semiconductor laser gyro)
The gyro of the present invention includes a first photodetector arranged at a position where an interference fringe is formed by the first and second lasers, and a second for measuring the amount of laser light that has passed through the Fabry-Perot etalon. Photo detector. The first photodetector is not particularly limited as long as it can detect the movement of interference fringes, and usually a semiconductor light receiving element such as a photodiode or a phototransistor is used. The first photodetector outputs a signal corresponding to the intensity of the interference fringes. When the interference fringe moves, the amount of light input to the first photodetector changes periodically, so that the movement speed of the interference fringe can be calculated. A known semiconductor element such as a photodiode or a phototransistor can also be applied to the second photodetector. A waveguide type photodiode may be used.

  The first photodetector may include a plurality of light receiving elements. By arranging two or more light receiving elements in the moving direction of the interference fringes, the moving direction of the interference fringes can be detected in addition to the moving speed of the interference fringes. By detecting the moving speed and moving direction of the interference fringes, the rotating direction and rotating speed of the semiconductor laser gyro can be calculated.

  In the gyro of the present invention, the semiconductor laser and the first photodetector (light receiving element) may be formed monolithically. In this case, the semiconductor laser and the first photodetector (for example, a photodiode) may have the same stacked structure. In this configuration, the semiconductor laser and the first photodetector can be simultaneously formed by a series of processes for manufacturing a semiconductor element. Therefore, the manufacturing is easy, and the semiconductor laser and the photodetector can be formed in an accurate arrangement.

  In the semiconductor laser gyro of the present invention, at least one laser beam selected from the laser beam (L1) and the laser beam (L2) emitted from the second end face of the active layer passes through the Fabry-Perot etalon, Monitored by a photo detector. A Fabry-Perot etalon is an element whose transmittance periodically changes with changes in wavelength. A known Fabry-Perot etalon can be used as the Fabry-Perot etalon, and it is preferable to select an etalon whose transmittance changes rapidly in the vicinity of the wavelength of the laser beam used in the present invention.

  The semiconductor laser gyro according to the present invention is formed by bending a laminated portion including first and second layers arranged in order from the substrate side on a substrate, and bending the first and second layers to the second layer side. It may further include two raised portions. In this case, each of the stacked portion and the upright portion includes a plurality of layers having different lattice constants from each other, and the first and second layers are bent by the force generated by the difference in the lattice constant in the plurality of layers. Is formed. The Fabry-Perot etalon may be formed by two upright portions.

  The semiconductor laser gyro of the present invention may include a lens on the optical path between the second end face and the Fabry-Perot etalon. The lens is arranged to make the laser light emitted from the second end face substantially parallel light. In this case, the gyro is formed by bending the first and second layers to the second layer side, and the stacked portion including the first and second layers arranged in order from the substrate side on the substrate. An upright part may be further included. Each of the stacked portion and the standing portion includes a plurality of layers having different lattice constants, and the first and second layers are bent by the force generated by the difference in the lattice constant in the plurality of layers, so that the standing portions are It is formed and the lens may be formed in the standing part. A Fresnel lens can be formed on the standing part.

  The gyro of the present invention may further include a lens (for example, a spherical lens) or a prism for superimposing the first and second laser beams. These lenses and prisms may be disposed on the substrate on which the semiconductor laser is formed, or may be disposed outside the substrate.

  The principle of the semiconductor laser gyro of the present invention using the Sagnac effect (sagnac effect) will be briefly described with reference to FIG. When the semiconductor laser 10 rotates, the time required to go around the optical path of the path 32 varies between the laser light L1 and the laser light L2. Since the speed of light is constant, when the semiconductor laser 10 rotates, a frequency difference is generated between the laser light L1 and the laser light L2, and the interference fringes move at a speed corresponding to the frequency difference. The movement direction of the interference fringes changes according to the rotation direction of the semiconductor laser 10. Therefore, the rotational speed (angular speed) of the semiconductor laser 10 can be calculated by measuring the moving speed of the interference fringes, and the rotational direction of the semiconductor laser can be detected by detecting the moving direction of the interference fringes. More specifically, the rotation direction and rotation speed in a plane parallel to the surface of the active layer 26 can be calculated. As described above, the principle of such an optical gyro is a known principle, and is used in an optical gyro using a rare gas laser. Therefore, the semiconductor laser gyro of the present invention can be driven by a known driving circuit, and information obtained by the gyro can be processed by a known method. Note that by combining three semiconductor laser gyros of the present invention, the rotation direction and rotation speed in all directions can be calculated.

  Hereinafter, the semiconductor laser gyro of the present invention will be described with examples.

(Embodiment 1)
FIG. 7 shows a top view of the gyro 70a of the first embodiment. The gyro 70a includes the semiconductor laser 10, the prism 71, the rotation detection photodetector 72, the lens 73, the half mirror 74, the power monitor photodiode 75, the Fabry-Perot etalon 76, the wavelength, and the like. And a monitoring photodiode 77. Known optical elements such as optical elements and photodiodes can be used. The semiconductor laser 10 and other optical elements and semiconductor elements may be disposed on the same substrate or may be disposed on different substrates.

  FIG. 8 schematically shows the relationship between the semiconductor laser 10, the prism 71, the photodetector 72, and the two laser beams emitted from the first end face of the semiconductor laser 10. The two laser beams emitted from the semiconductor laser 10 are overlapped by the prism 71 to generate interference fringes. The movement of the interference fringes is observed by the two photodiodes 72a and 72b of the photodetector 72. The interference fringes move in the direction of the arrow at a speed corresponding to the rotational speed of the gyro 70a. The movement direction of the interference fringes changes corresponding to the rotation direction of the gyro 70a.

  The shape of the prism 71 is determined according to conditions such as the angle and interval between the two incident laser beams and the distance from the photodetector 72. In order to increase the period length of the interference fringes, it is preferable that the largest angle of the triangle which is the cross-sectional shape of the prism 71 is slightly larger than 90 ° (0.5π radians). If the angle is (0.5π + ε) radians, ε is preferably 0.5 radians or less.

  As shown in FIG. 7, the laser light emitted from the second end face of the semiconductor laser 10 is made into substantially parallel light by the lens 73 and enters the half mirror 74. The intensity of the laser beam transmitted through the half mirror 74 is measured by a power monitoring photodiode 75. On the other hand, the intensity of the laser beam reflected by the half mirror 74 is measured by a photodiode 77 after passing through a Fabry-Perot etalon 76.

  The Fabry-Perot etalon 76 shows the wavelength dependency of the transmittance as shown in FIG. As the Fabry-Perot etalon 76, an etalon having a large change in transmittance with respect to the wavelength in the vicinity of the typical wavelength 91 of the laser light emitted from the semiconductor laser 10 is selected. For example, when the wavelength of the laser beam is in the vicinity of 850 nm, a crystalline lens having a refractive index of 1.46 and a length in the optical axis direction of 200 nm can be used. In this etalon, the wavelength interval between the transmittance peaks is about 1.24 nm in the vicinity of the wavelength of 850 nm.

  When the wavelength of the semiconductor laser 10 is shifted from the typical wavelength 91 to the wavelength 92 or the wavelength 93, the intensity of the laser beam 76 passing through the Fabry-Perot etalon changes greatly, and the output of the photodiode 77 increases or decreases correspondingly. On the other hand, the intensity of the laser light emitted from the second end face of the semiconductor laser 10 also changes due to temperature, deterioration with time, etc., and affects the output of the photodiode 77. Therefore, a change in the intensity of the laser light emitted from the second end face is detected by the photodiode 75 and emitted from the semiconductor laser 10 based on a change in the ratio of the output of the photodiode 77 to the output of the photodiode 75. A wavelength change of the laser beam is detected. Then, based on the detected wavelength change, control is performed so as to cancel the wavelength change. Specifically, for example, the wavelength is controlled by changing the substrate temperature or the injection current. In this way, the wavelength of the laser light emitted from the semiconductor laser 10 can be stabilized.

  When the gyro is rotated, the wavelength of the laser light that circulates in the rhombic path in the semiconductor laser 10 also changes. This change is a change in the frequency to be detected using a Fabry-Perot etalon, that is, a temperature, It is sufficiently smaller than the change in frequency due to the change in injection current.

(Embodiment 2)
In the second embodiment, an example in which an optical element for wavelength monitoring and a photodetector are formed on the same substrate as the semiconductor laser 10 will be described. A gyro 70b of Embodiment 2 is shown in FIG. Since this gyro differs from the first embodiment only in the method of forming the optical element for wavelength monitoring, the overlapping description is omitted.

  The gyro 70b includes a semiconductor laser 10, a prism 71, a photodetector 72 for detecting rotation, a Fresnel lens 81, a half mirror 82, a photodiode 75 for power monitoring, a Fabry-Perot etalon 83, and a wavelength monitor. And a photodiode 77 for use. The Fabry-Perot etalon 83 is an air gap type etalon in which two half mirrors 83a and 83b are arranged at a constant interval. In order to prevent the light reflected by the surface of the Fresnel lens 81 from entering the semiconductor laser 10, it is preferable that the Fresnel lens 81 is disposed slightly inclined with respect to the optical axis.

  The gyro 70b includes a plurality of layers formed on the substrate. And the standing part which stood | started up from the board | substrate is formed by bending a part of those layers. The lens 81 and the half mirrors 82, 83a and 83b are formed on the upright portion.

  As shown in FIG. 11, in the portion where the standing portion is formed, the buffer layer 111, the layer (sacrificial layer) 112, the hinge layer (laminated portion) 113, the etch stop layer 114, and the compensation layer, which are sequentially arranged from the substrate 11 side A multilayer film including 115 and the functional layer 116 is formed. The hinge layer 113 includes a first layer 113a and a second layer 113b arranged in this order from the substrate 11 side.

  The substrate 11 is the substrate described in the description of the semiconductor laser 10. The buffer layer 111 is a layer formed to increase the crystallinity of the layer formed thereon, and the buffer layers 21 and 22 described above can be applied.

  The layer 112 is a layer from which part is selectively removed to form an upright portion (see FIG. 14A). Thus, layer 112 is formed of a material that can be selectively removed.

  The hinge layer 113 is a layer for bending the semiconductor layer by the difference in lattice constant between the plurality of semiconductor layers. Therefore, the first layer 113a is formed using a semiconductor having a larger lattice constant than the semiconductor included in the second layer 113b. For example, a first layer 113a made of InGaAs and a second layer 113b made of GaAs can be used. The angle at which the hinge layer 113 is bent can be adjusted by changing the composition ratio, thickness, and length of the bent portion of these semiconductor layers.

For example, when the bent portion is formed using the first layer 113a made of In _0.2 Ga _0.8 As and the second layer 113b made of GaAs, the radius of curvature R of the bent portion is usually expressed by the following equation. Is done.
R = (a / Δa) · {(t1 + t2) / 2}
Here, a is the lattice constant of the second layer 113b (GaAs layer). Δa is the difference between the lattice constant of the first layer 113a (In _0.2 Ga _0.8 As layer) and the lattice constant of the second layer 113b (GaAs layer). Further, t1 is the thickness (unit: angstrom) of the first layer 113a, and t2 is the thickness (unit: angstrom) of the second layer 113b.

  The hinge layer may be composed of three or more layers. For example, when the layer A having a large lattice constant and the layer B having a small lattice constant are laminated such as thick layer A / layer B / thin layer A, the stress applied to the layer B by the thick layer A is thinner. Is larger than the stress exerted on the layer B, so that a total stress that tends to bend on the thin layer A side is generated. Similarly, in the laminated film of thick layer B / layer A / thin layer B, a stress that tends to bend toward the thick layer B is generated in total. By utilizing such a relationship, a plurality of stacked layers can be bent in a predetermined direction.

  The functional layer 116 is a layer that exhibits a function as an optical element. In the case of forming a Fresnel lens, the lens is formed by etching the functional layer 116. In the case of forming a half mirror, the functional layer 116 forms a half mirror, or a layer that functions as a half mirror is further formed on the compensation layer 115. The compensation layer 115 is a layer for canceling the stress generated by the hinge layer 113. Note that when the deformation by the hinge layer 113 can be prevented by the functional layer 116, the compensation layer 115 can be omitted.

  Hereinafter, a method of forming the standing portion including the Fresnel lens 81 will be described with reference to FIG. 12B, 12D, and 12F are top views. FIGS. 12A, 12C, and 12E are cross-sectional views of FIGS. 12B, 12D, and 12F, respectively.

  First, as shown in FIG. 12A, the buffer layer 111, the layer 112, the first layer 113a, the second layer 113b, the etch stop layer 114, the compensation layer 115, and the functional layer 116 are formed on the substrate 11. To do. These layers can be formed by a known method, for example, an MBE (Molecular Beam Epitaxy) method or a CVD (Chemical Vapor Deposition) method. 2 may be stacked on the buffer layer 22 after the part of the multilayer film in FIG. 2 is etched to the surface of the buffer layer 22.

  When forming the Fresnel lens 81, the functional layer 116 can be formed of, for example, acrylic resin, polycarbonate, or photoresist. A pattern of the Fresnel lens 81 is formed on the functional layer 116. FIG. 13A shows a plan view and FIG. 13B shows a cross-sectional view of an example of the Fresnel lens pattern. Such a pattern can be formed by forming a large number of stepped steps so as to correspond to the slopes forming the Fresnel lens. Such a stepped step can be formed by repeating photolithography and etching. An antireflection film may be formed on the surface of the Fresnel lens in order to reduce the reflection loss when the laser beam is incident.

  Next, as shown in FIGS. 12C and 12D, a groove 121 reaching the surface of the second layer 113b, a groove 122 reaching the layer 112, and a groove 123 deeper than the surface of the substrate 11 Form. These can be formed by a known etching method depending on the material of each layer. The groove 121 includes two groove parts 121a and 121b arranged so as to be orthogonal to each other. These grooves are formed in a portion that becomes a bent portion. The groove 122 is formed in a portion that is cut off from the multilayer film on the substrate 11 when the standing portion is formed. The groove 123 is a groove having a substantially V-shaped cross section. The groove 123 is formed at a position where the Fresnel lens is disposed.

  Next, as shown in FIGS. 12E and 12F, the layer 112 located under the portion surrounded by the groove 121a, the groove 122, and the groove 123 is selectively removed by wet etching. As an etchant for wet etching, for example, hydrofluoric acid can be used.

  When the layer 112 is removed, only the first layer 113a made of InGaAs and the second layer 113b made of GaAs exist in the groove 121a (first bent portion). Since InGaAs has a larger lattice constant than GaAs, in the groove 121a, the first layer 113a and the second layer 113b are bent toward the second layer 113b, and the first bent portion 141 (FIG. 14). (See (a)) is formed. Thereby, a part of the multilayer film (the first layer 113a to the functional layer 116) rises from the substrate 11, and an upright portion is formed. Similarly, also in the groove 121b, the first layer 113a and the second layer 113b are bent toward the second layer 113b, and the second bent portion 142 (see FIG. 14A) is formed.

  FIGS. 14A and 14B are a perspective view and a cross-sectional view schematically showing the structure of the upright portion 140, respectively. When the hinge layer is bent at a substantially right angle at the two bent portions 141 and 142, the upright portion 140 includes a first flat surface portion 140a and a second flat surface portion 140b arranged to be orthogonal to each other. A part of the second flat surface portion 140 b is fitted in the groove 123, and the second flat surface portion 140 b rises substantially perpendicular to the surface of the substrate 11. In this method, the upright portion 140 can be easily arranged by embedding a part of the second flat surface portion 140b in the groove 123. Further, in this method, a Fresnel lens can be arranged near the surface of the substrate 11. This makes it possible to collect laser light that moves near the surface of the substrate 11.

  When forming a half mirror, the functional layer 116 can be formed, for example, by combining a layer of the same material as the Fresnel lens and a semiconductor layer. Unlike Fresnel lenses, the surface of these mirrors is flat. When forming a Fabry-Perot etalon, it is only necessary to form two upright portions that function as half mirrors at a predetermined distance apart.

  As shown in FIG. 14, these optical elements can be formed on an upright portion that is partially fitted in the groove. However, optical elements that do not need to be formed on the standing part need not be formed on the standing part.

  The laser beam may be condensed using a concave mirror (Fresnel mirror) instead of the Fresnel lens 81. An example of a gyro using a Fresnel mirror is shown in FIG. 15 includes a semiconductor laser 10, a prism 71, a rotation detection photodetector 72, a Fresnel mirror 151, a half mirror 82, a power monitoring photodiode 75, and a Fabry-Perot etalon 83. And a photodiode 77 for wavelength monitoring. About parts other than the Fresnel mirror 151, it is the same as that of the gyro 70b.

  The Fresnel mirror 151 is a mirror that functions as a concave mirror. The Fresnel mirror 151 has, for example, a surface shape obtained by inverting the surface shape of the Fresnel lens 81, and the surface is coated with a metal film. The Fresnel mirror 151 can be formed by depositing a metal film after etching the functional layer 116 into a predetermined shape in the same manner as the Fresnel lens 81.

  In the gyro 70c, the laser light emitted from the second end face of the semiconductor laser 10 is made substantially parallel light by the Fresnel mirror and enters the half mirror 82. The light quantity of the laser light reflected by the half mirror 82 is measured by the photodiode 75. On the other hand, the laser beam that has passed through the half mirror 82 enters the Fabry-Perot etalon 83, and the amount of light after passing through it is measured by the photodiode 77. In the gyro 70c, the wavelength of the laser beam can be stabilized as in the gyro 70b.

(Manufacturing method of semiconductor laser gyro)
There is no limitation in the manufacturing method of the semiconductor laser used with the gyro of this invention, It can manufacture with a well-known semiconductor manufacturing technique. The gyro of the present invention can be easily manufactured by assembling a semiconductor laser and other members by a known technique. Hereinafter, an example of a method for manufacturing the semiconductor laser 10 will be described.

  16A to 16H schematically show the manufacturing process. 16A to 16H, the surface of the insulating layer 12 is hatched to facilitate understanding of the formation state of the insulating layer 12.

First, as shown in FIG. 16A, a semiconductor layer 20a composed of a plurality of semiconductor layers and an insulating layer 12a having a thickness of 0.4 μm are formed on a substrate 11. The semiconductor layer 20a is a layer that becomes the semiconductor layer 20 (see FIG. 2 and Table 1) by etching. Each layer constituting the semiconductor layer 20a can be formed by a general method, for example, an MBE (Molecular Beam Epitaxy) method or a CVD (Chemical Vapor Deposition) method. The insulating layer 12a is made of, for example, Si ₃ N ₄ or SiO ₂ . The insulating layer 12a can be formed by a method such as sputtering or CVD.

  Next, as shown in FIG. 16B, a patterned resist film 161 is formed on the insulating layer 12a. The resist film 161 is patterned into the shape of the active layer 26 shown in FIG.

  Next, as shown in FIG. 16C, the resist film 161 is used as a mask to etch the insulating layer 12a, the semiconductor layer 20a, and part of the substrate 11, and then the resist film 161 is removed. Etching is performed by RIE (Reactive Ion Etching), and etching is performed to at least the depth of the cladding layer 24. The insulating layer 12 and the semiconductor layer 20 having a predetermined shape are formed by etching. Etching is performed under conditions such that the verticality and smoothness of the side surfaces of the semiconductor layer 20 are high. Such conditions are commonly employed in semiconductor manufacturing processes. By etching, the planar shape of all the semiconductor layers constituting the semiconductor layer 20 becomes substantially the same as the planar shape of the active layer 26 shown in FIG. Further, the side surface of the semiconductor layer 20 functions as a mirror surface.

  Next, as shown in FIG. 16D, a substantially diamond-shaped through hole 12h is formed in the insulating layer 12 so as to correspond to the region 31 (see FIGS. 2 and 4). The through hole 12h can be formed by a general photolithography / etching process.

  Next, as illustrated in FIG. 16E, a resist film 162 is formed so as to cover the entire surface of the substrate 11. At this time, in order to fill a step between the surface of the substrate 11 and the surface of the insulating layer 12, the resist film 162 is preferably formed of two layers, a resist layer 162a and a resist layer 162b. The resist film 162 can be formed by applying the resist layer 162b after applying the resist layer 162a to the entire surface of the substrate 11 to fill the steps. According to this method, the resist film 162 with high surface flatness can be formed.

  Next, as illustrated in FIG. 16F, the resist film 162 is patterned to form a through hole 162 h in the resist film 162. The through hole 162h is formed in a shape corresponding to a region where the first electrode 13 is formed. After the through-hole 162h is formed, the surface of the semiconductor layer 20 (cap layer 29) in the through-hole 162h so that good contact can be obtained between the semiconductor layer 20 (cap layer 29) and the first electrode 13. Is etched about 0.01 μm to 0.02 μm.

  Next, as shown in FIG. 16G, the first electrode 13 is formed. The first electrode 13 can be formed by a lift-off method. Specifically, first, using the resist film 162 as a mask, a plurality of metal layers constituting the first electrode 13 are sequentially formed by an electron beam method. Thereafter, the resist film 162 is removed with acetone. In this way, the first electrode 13 having a predetermined shape can be formed. The first electrode 13 is in contact with the semiconductor layer 20 (cap layer 29) through the through hole 12h formed in the insulating layer 12.

  When a large number of semiconductor lasers are formed using a single substrate 11 (wafer), the back surface of the substrate 11 is polished so that the thickness of the substrate 11 becomes 100 to 150 μm in order to facilitate cleavage of the substrate 11. It is preferable.

  Next, as shown in FIG. 16H, a plurality of metal layers are sequentially formed on the back surface side of the substrate 11 by vapor deposition to form the second electrode 14. Then, in order to alloy the metal layer which comprises the 1st electrode 13 and the 2nd electrode 14, it heat-processes at 400-450 degreeC. Finally, the substrate 11 is cleaved for each semiconductor laser as necessary.

  In this way, the semiconductor laser 10 is formed. When a photodiode having the same stacked structure as that of the semiconductor laser 10 is formed monolithically, the resist films 161 and 162 are patterned so as to correspond to a portion where the semiconductor laser is formed and a portion where the photodiode is formed. That's fine. Similarly, in the case of forming a prism having the same stacked structure as the semiconductor layer of the semiconductor laser, the resist film 161 may be patterned so as to correspond to the portion where the semiconductor laser is formed and the portion where the prism is formed.

  Note that other optical elements and electronic components other than the photodetector and the prism may be formed on the substrate 11. For example, a driving circuit for driving the semiconductor laser or a circuit for processing a signal output from the photodetector may be formed. Moreover, you may further apply the well-known technique used for the conventional gyro to the semiconductor laser gyro of this invention.

  The embodiments of the present invention have been described above by way of examples, but the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.

  For example, in the above embodiment, the method of stabilizing the wavelength using only one laser beam out of the two laser beams emitted from the second end face has been described, but both may be used.

  The semiconductor laser gyro of the present invention can be applied to various devices that need to detect the rotation of an object. As a typical example, it can be used for an attitude control device, a navigation device, and a camera shake correction device. Specifically, the gyro of the present invention can be used for moving means such as aircraft such as rockets and airplanes, automobiles and motorcycles. Further, the gyro of the present invention can be used for a portable information terminal such as a mobile phone or a small personal computer, a toy, a camera, etc. by taking advantage of being ultra-small and easy to handle.

It is a perspective view which shows typically an example of the semiconductor laser used for the semiconductor laser gyro of this invention. It is sectional drawing which shows the semiconductor laser shown in FIG. 1 typically. It is a figure which shows typically the planar shape of the active layer of the semiconductor laser shown in FIG. It is a figure explaining the function of the semiconductor laser shown in FIG. It is a figure which shows typically the band gap profile of the semiconductor layer of the semiconductor laser shown in FIG. It is a figure which shows typically the refractive index of the active layer vicinity of the semiconductor laser shown in FIG. It is a top view which shows typically the structure of an example of the semiconductor laser gyro of this invention. It is a schematic diagram which shows the optical path of a part of laser beam in the semiconductor laser gyro shown in FIG. It is a graph which shows typically the function of a Fabry-Perot etalon. It is a top view which shows typically the structure of another example of the semiconductor laser gyro of this invention. It is sectional drawing which shows typically an example of the laminated structure of the multilayer film in the part which forms an upright part. It is process drawing which shows typically an example of the formation method of the standing part containing a Fresnel lens. It is (a) front view and (b) sectional drawing which show an example of a Fresnel lens typically. It is (a) perspective view and (b) sectional view showing typically an example of a standing part containing a Fresnel lens. It is a top view which shows typically the structure of another example of the semiconductor laser gyro of this invention. It is a perspective view which shows typically an example of the manufacturing process of the semiconductor laser used with the semiconductor laser gyro of this invention. It is a figure which shows typically the structure of the conventional optical gyroscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor laser 11 Board | substrate 12 Insulating layer 12h Through-hole 13 1st electrode 14 2nd electrode 20 Semiconductor layer 21, 22, 111 Buffer layer 23 Graded layer 24 Cladding layer 25 Graded layer 26 Active layer 26a-26d (1st 1st to 4th) end face 26f first region 26s second region 27 graded layer 28 cladding layer 29 cap layer 32 rhombic path 32a to 32d (first to fourth) corner 35 first laser light 36 2nd laser beam 70a, 70b, 70c Semiconductor laser gyro 71 Prism 72 Photo detector (first photo detector)
72a, 72b Photodiode 73 Lens 74, 82, 83a, 83b Half mirror 75 Photodiode (third photodetector)
76, 83 Fabry-Perot etalon 77 Photodiode (second photodetector)
81 Fresnel lens 113 Hinge layer (lamination part)
113a First layer 113b Second layer 115 Compensation layer 116 Functional layer 140 Standing portion 141, 142 Bending portion 151 Fresnel mirror 161, 162 Resist film L1, L2 Laser light

Claims (7)

A substrate, a semiconductor laser disposed on the substrate and emitting first and second laser beams, a first photodetector for rotation detection, a second photodetector for wavelength monitoring, and a Fabry-Perot A semiconductor laser gyro comprising an etalon and wavelength control means for controlling the wavelengths of the first and second laser beams,
The first photodetector is arranged at a position where an interference fringe is formed by the first and second laser beams,
The semiconductor laser includes an active layer having first and second end faces facing each other,
The first laser beam is a laser beam in which a part of the laser beam (L1) that circulates on the rhombic path in the active layer is emitted from the first end face,
The second laser beam is a laser beam in which a part of the laser beam (L2) that circulates in the direction opposite to the laser beam (L1) on the path is emitted from the first end surface,
At least one laser beam selected from the laser beam (L1) and the laser beam (L2) emitted from the second end face is monitored by the second photodetector via the Fabry-Perot etalon. A semiconductor laser gyro that stabilizes the wavelengths of the first and second laser beams by the wavelength control unit based on the output of the second photodetector. A third photodetector for monitoring the amount of the at least one laser beam emitted from the second end face;
2. The wavelength of the first and second laser beams is stabilized by the wavelength control unit based on the output of the second photodetector and the output of the third photodetector. 3. Semiconductor laser gyro.   3. The semiconductor laser gyro according to claim 1, wherein each of the first and second end surfaces is an outwardly convex curved surface.   The semiconductor laser gyro according to claim 1, wherein the first photodetector includes a plurality of light receiving elements. A laminated portion including first and second layers disposed in order from the substrate side on the substrate; and two formed by bending the first and second layers to the second layer side And a standing part,
Each of the stacked portion and the standing portion includes a plurality of layers having different lattice constants from each other,
The first and second layers are bent by a force generated by a difference in lattice constant in the plurality of layers to form the upright portion;
3. The semiconductor laser gyro according to claim 1, wherein the Fabry-Perot etalon is formed by the two upright portions.   3. The semiconductor laser gyro according to claim 1, further comprising a lens on an optical path between the second end face and the Fabry-Perot etalon. A laminated portion including first and second layers arranged in order from the substrate side on the substrate, and an upright portion formed by bending the first and second layers to the second layer side And further including
Each of the stacked portion and the standing portion includes a plurality of layers having different lattice constants from each other,
The first and second layers are bent by a force generated by a difference in lattice constant in the plurality of layers to form the upright portion;
The semiconductor laser gyro according to claim 6, wherein the lens is formed on the upright portion.