JP2009145110A - Optical gyroscope element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new optical gyroscope element easily manufactured and having low electric power consumption. <P>SOLUTION: An optical gyroscope element determines rotational angular speed on the basis of the frequency difference between laser beams L1 and L2 propagating through a ring-like optical path 50 in the opposite directions. The optical gyroscope element is provided with: an optical waveguide 11 formed in a first substrate 10; a semiconductor optical amplifier 40 formed in a second substrate, an extraction means for extracting part of the laser beams L1 and L2 from the ring-like optical path 50; a photodiode 31 for observing the frequency difference between laser beams L1 and L2; and a mounting substrate 70. The semiconductor optical amplifier 40 includes an optical waveguide 22 at least the part of which is an optical amplifying region. The first substrate 10 and the semiconductor optical amplifier 40 are arranged on the mounting substrate 70 in such a way that two end parts of the optical waveguide 11 and two end parts of the optical waveguide 22 are connected to one another. The optical waveguide 11 and the optical waveguide 22 form the ring-like optical path 50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical gyro element.

  Among the gyros for detecting the rotational angular velocity of the rotating object, the optical gyro has a feature of high accuracy. In the optical gyro, the rotational angular velocity is detected by 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.

Further, as an optical gyro with low power consumption, a gyro using a semiconductor laser element including a triangular ring resonator (active layer) has been proposed (for example, see Patent Document 2). This semiconductor laser gyro includes a light receiving element for observing interference fringes of laser light in addition to the semiconductor laser element.
Japanese Patent Laid-Open No. 11-351881 JP 2000-230831 A

  However, the manufacturing process of the semiconductor laser gyro is complicated, and in particular, if a plurality of elements constituting the semiconductor laser gyro are monolithically formed on one substrate, the manufacturing process becomes extremely complicated.

  In such a situation, an object of the present invention is to provide a novel optical gyro element that is easy to manufacture and consumes less power.

  In order to achieve the above object, an optical gyro element of the present invention is an optical gyro element that obtains a rotational angular velocity from a frequency difference between first and second laser beams that propagate in an annular optical path in opposite directions. A first optical waveguide formed on one substrate, a semiconductor optical amplifier formed on a second substrate, a drawing means for extracting a part of the first and second laser beams from the annular optical path, An observation means for observing a frequency difference between the extracted first and second laser beams and a mounting substrate, and the semiconductor optical amplifier includes a second optical waveguide at least a part of which is an optical amplification region The first and second end portions of the first optical waveguide are present on one side surface of the first substrate, and the first and second end portions of the second optical waveguide are The first light is present on one side surface of the second substrate. The first end of the waveguide and the first end of the second optical waveguide are coupled, and the second end of the first optical waveguide and the second optical waveguide The first substrate and the semiconductor optical amplifier are disposed on the mounting substrate so as to be coupled to the second end, and the first optical waveguide and the second optical waveguide The annular optical path is formed.

  In the optical gyro element of the present invention, an annular optical waveguide can be easily formed by abutting a substrate on which a semiconductor optical amplifier is formed with a substrate on which an optical waveguide is formed. Therefore, manufacture is easy compared with the conventional optical gyro.

  Hereinafter, the present invention will be described with examples. However, the present invention is not limited to the examples described below. In the following description, specific materials and specific numerical values may be exemplified, but other materials and other numerical values may be applied as long as the effect of the present invention is obtained.

[Optical Gyro Element (Optical Gyro)]
The optical gyro element of the present invention is an optical gyro element that obtains the rotational angular velocity from the frequency difference between the first and second laser beams propagating in opposite directions to each other in an annular optical path. The optical gyro element includes a first optical waveguide formed on a first substrate, a semiconductor optical amplifier formed on a second substrate, extraction means, observation means, and a mounting substrate.

  The first optical waveguide is formed on the first substrate. Two end portions (first and second end portions) of the first optical waveguide exist on one side surface side of the first substrate. The first substrate is not limited as long as the first optical waveguide can be formed on the substrate.

In a typical example, the first optical waveguide includes a core layer and a clad layer that is disposed around the core layer and has a refractive index lower than that of the core layer. Although there is no particular limitation on the width, thickness, and length of the core layer, it is preferable to design the width and thickness of the core layer so that the higher-order mode becomes a suppressed fundamental mode. These values are preferably determined based on the refractive index and the oscillation wavelength. The first optical waveguide is preferably formed of a material with as little loss as possible of the first and second laser beams. In a preferred example of the first optical waveguide, the core layer is made of Ge-doped SiO ₂ and the cladding layer is made of non-doped SiO ₂ .

  The length of the first optical waveguide is not limited as long as the effects of the present invention can be obtained. In one example, the length of the first optical waveguide may be in the range of 1 mm to 100 mm.

  A semiconductor optical amplifier (SOA) is formed on the second substrate. The second substrate is not limited as long as it can form a semiconductor optical amplifier.

  The semiconductor optical amplifier includes an optical waveguide (second optical waveguide) at least part of which is an optical amplification region. The second optical waveguide in the optical amplification region includes an active layer. By injecting current into the active layer, light passing through the second optical waveguide is amplified. When the current injected into the active layer exceeds the threshold value, the laser beam is excited.

  The entire second optical waveguide may be an optical amplification region. Further, a part of the second optical waveguide may not be the optical amplification region. For example, a part of the second optical waveguide may be a passive region that does not amplify light. Further, the two end portions of the second optical waveguide may be a mode field conversion region (spot size conversion region). The second optical waveguide other than the optical amplification region is preferably formed of a material with a small loss of the first and second laser beams.

  The length of the second optical waveguide is not limited as long as the effect of the present invention is obtained. In one example, the length of the second optical waveguide may be in the range of 0.1 mm to 10 mm.

  As long as the effects of the present invention are obtained, the structure of the semiconductor optical amplifier is not particularly limited. The structure of the optical amplification region of the semiconductor optical amplifier is selected according to the first and second laser beams to be excited. For example, a semiconductor optical amplifier including an active layer made of a III-V group compound semiconductor can be used. The wavelengths of the first and second laser beams excited by such a semiconductor optical amplifier are in the range of 0.25 μm to 3 μm, for example. An example of a semiconductor optical amplifier includes two electrodes, two cladding layers disposed between the electrodes, and an active layer disposed between the cladding layers.

  Two end portions (first and second end portions) of the second optical waveguide exist on one side surface side of the second substrate. Then, the first end of the first optical waveguide and the first end of the second optical waveguide are coupled, and the second end of the first optical waveguide and the second optical waveguide The first substrate and the semiconductor optical amplifier (second substrate) are arranged on the mounting substrate so as to be coupled to the second end. An annular optical path is formed by the coupling of these ends. That is, an annular optical path is formed by the first optical waveguide and the second optical waveguide.

  Usually, a light receiving element is also mounted on the mounting substrate. Usually, an electrode pad connected to one electrode of the semiconductor optical amplifier and an electrode pad connected to one electrode of the light receiving element are formed on the surface of the mounting substrate.

  In the optical gyro element of the present invention, the first and second laser beams propagating in opposite directions through the annular optical path formed by the first and second optical waveguides are excited. The shape of the annular optical path is not particularly limited as long as the first and second laser beams are excited. The annular optical path may be annular or may not be annular. The shape of the annular optical path may be, for example, an annular shape in which a portion of the second optical waveguide protrudes outward.

  The extraction means extracts a part of the first and second laser beams from the annular optical path. Specifically, the extraction unit extracts part of the first and second laser beams from the second optical waveguide. The extraction means may include an optical coupler for extracting the first and second laser beams from the second optical waveguide. An example of such a drawing means is an optical waveguide that functions as an optical coupler.

  The observation means observes the frequency difference between the first and second laser lights drawn out from the annular optical path. The observation means includes at least one light receiving element for observing the first and second laser beams. A typical example of the observation means is a superposition means for superimposing the first and second laser beams extracted by the extraction means, and a light receiving element for observing the superposed first and second laser lights. including. An optical coupler can be used as the superimposing means. In a typical example of the present invention, an optical waveguide that functions as a drawing unit and an optical waveguide that functions as an overlapping unit are formed on the first substrate. One optical waveguide may also serve as an optical waveguide that functions as a drawing unit and an optical waveguide that functions as a superimposing unit.

  A photodiode or a phototransistor can be used as the light receiving element. The light receiving element is preferably formed on a substrate different from the first and second substrates. Then, it is preferable that the light receiving element and the optical waveguide through which the first and second laser beams are propagated are coupled by abutting the substrate on which the light receiving element is formed with the first substrate. In order to facilitate coupling with the optical waveguide, it is preferable to use a waveguide type photodiode as the light receiving element. In that case, it is preferable that the end face of the waveguide of the photodiode is inclined by several degrees with respect to the optical axis so that the laser light reflected on the end face of the photodiode does not return to the optical waveguide.

  A signal including information on the frequencies of the first and second laser beams is output from the light receiving element of the observation means. Based on this signal, the rotational angular velocity of the gyro is determined. The output signal of the light receiving element is input to a spectrum analyzer, for example, and processed and analyzed.

  There is no limitation on the shape of the surface of the mounting substrate, as long as the first substrate and the semiconductor optical amplifier (and the light receiving element) can be easily mounted at accurate positions. The surface of the mounting substrate may or may not be flat. By using a mounting substrate having a flat surface, the arrangement and replacement of the first substrate and the semiconductor optical amplifier are facilitated. Similarly, accurate arrangement of the light receiving elements is facilitated.

  As long as the effects of the present invention can be obtained, the planar shape of the second optical waveguide is not limited. The planar shape of the second optical waveguide may be U-shaped. The planar shape of the second optical waveguide may be an arc shape.

  In an example of the optical gyro element of the present invention, the observation means includes at least one optical waveguide (third optical waveguide) for superimposing the extracted first and second laser beams, and the superimposed first and second optical waveguides. And a light receiving element for observing the second laser beam. In this example, the third optical waveguide (at least one optical waveguide) is formed on the first substrate, and the light receiving element is disposed on the mounting substrate. A part of the third optical waveguide can function as a drawing means.

  In the optical gyro element of the present invention, a waveguide-type optical element or optical device may be disposed in the middle of the optical waveguide as necessary.

[Optical Gyro Element Manufacturing Method]
Hereinafter, a method for manufacturing the optical gyro element of the present invention will be described. The individual steps of the manufacturing method of the present invention can be carried out using a general method used in a method for manufacturing a semiconductor device.

  The method for manufacturing an optical gyro element includes the following step (i). In step (i), the first substrate and the semiconductor are formed such that the first optical waveguide formed on the first substrate and the second optical waveguide of the semiconductor optical amplifier are combined to form an annular optical path. An optical amplifier is disposed on the mounting substrate. Usually, after the first substrate is disposed on the mounting substrate, the semiconductor optical amplifier is disposed on the mounting substrate. Since the first substrate, the first optical waveguide, the semiconductor optical amplifier, and the mounting substrate have been described above, overlapping descriptions are omitted. Each of these can be formed by a known method.

  Since the two end faces of the first optical waveguide are present on one side of the first substrate, an antireflection film that covers these end faces can be formed at a time. Since the two end faces of the second optical waveguide exist on one side of the second substrate, an antireflection film covering these end faces can be formed at a time.

  The method for manufacturing the optical gyro element may include a step of arranging the light receiving element on the mounting substrate. This step can be performed before, during or after step (i). Usually, after arrange | positioning a 1st board | substrate on a mounting board | substrate, a 1st board | substrate and a light receiving element are arrange | positioned on a mounting board | substrate. Since the light receiving element has been described above, a duplicate description is omitted. The light receiving element is mounted at a position where it can receive the first and second laser light extracted from the annular optical path and superimposed.

  The first substrate, the semiconductor optical amplifier, and the light receiving element need to be accurately arranged so that their relative positions become predetermined positions. A known method used in a semiconductor element mounting technique may be applied to these accurate arrangements. For example, an alignment mark may be formed for each, and alignment may be performed using the alignment mark.

[Example of optical gyro element]
The configuration of an example of the optical gyro element of the present invention is schematically shown in FIG.

  The optical gyro element 100 of FIG. 1 includes a mounting substrate 70, a first substrate 10 mounted on the mounting substrate 70, a semiconductor optical amplifier 40, and a photodiode 31. A first optical waveguide 11 and a third optical waveguide 13 are formed on the first substrate 10. The semiconductor optical amplifier 40 includes a second optical waveguide 22. An annular optical path 50 is formed by the first optical waveguide 11 and the second optical waveguide 22.

  The first optical waveguide 11 and the third optical waveguide 13 are close to each other. This part functions as the optical coupler 51. Further, a part of the third optical waveguide 13 and the other part are close to each other so that their optical axes are parallel to each other. This portion functions as the optical coupler 52.

  The optical coupler 51 is formed so that the laser light traveling in the first optical waveguide 11 propagates to the third optical waveguide 13. In an example optical coupler, a part of the core layer of the third optical waveguide 13 is disposed adjacent to and substantially parallel to a tangent of a part of the core layer of the first optical waveguide 11. In this coupling portion, the shortest distance between the core layer of the first optical waveguide 11 and the core layer of the third optical waveguide 13 is set to a distance of about several times the oscillation wavelength or less, for example. . Similarly, the optical coupler 52 is also formed by arranging a part of the third optical waveguide 13 and another part of the third optical waveguide 13 adjacent to each other in parallel. In this example, the third optical waveguide 13 functions as a laser beam extraction unit and a laser beam superimposing unit.

A sectional view taken along line IIa-IIa in FIG. 1 is shown in FIG. The first substrate 10 is a quartz substrate. A Ge-doped core layer 14 is formed on the first substrate 10. An upper cladding layer 15 made of SiO ₂ is formed so as to cover the first substrate 10 and the core layer 14. The size of the cross section of the core layer 14 is, for example, about 5 μm square. The thickness of the upper cladding layer 15 is, for example, about 20 μm.

  Of the first substrate 10 and the upper cladding layer 15, a portion adjacent to the core layer 14 functions as an optical confinement layer. The core layer 14 and the optical confinement layer adjacent thereto constitute the first optical waveguide 11. The third optical waveguide 13 has the same structure as the first optical waveguide 11. Therefore, the cross-sectional view taken along line II in FIG. 1 is the same as the cross-sectional view shown in FIG. In this example, the case where a part of the first substrate 10 is a light confinement layer is shown, but all the light confinement layers may be formed on the first substrate.

  FIG. 2B shows an end face on the side where the two ends of the first optical waveguide 11 are exposed. The first end portion 11 m and the second end portion 11 n of the first optical waveguide 11 exist on the side surface 10 s side of the first substrate 10.

  The arrangement of the second optical waveguide 22 in the semiconductor optical amplifier 40 is shown in FIG. The planar shape of the second optical waveguide 22 is U-shaped. However, the two end portions and the region 22a in the vicinity thereof slightly expand outward. This is to prevent light reflected by the end face from returning to the optical waveguide.

  A sectional view taken along line IVa-IVa in FIG. 3 is shown in FIG. Referring to FIG. 4A, a semiconductor optical amplifier 40 includes a second substrate 20 and an active layer 41, a p-type cladding layer 42, and a p-type over cladding layer 43 that are stacked on the second substrate 20. , Cap layer 44 and upper electrode 45, and lower electrode 46. Further, the semiconductor optical amplifier 40 includes a p-InP layer 47 and an n-InP layer 48 stacked on the second substrate 20.

  The second substrate 20 is an n-InP substrate. The active layer 41 is made of GaInAsP. The p-type cladding layer 42 is made of p-InP. The p-type overclad layer 43 is made of p-InP. The cap layer 44 is made of p-type GaInAsP. The upper electrode 45 is a laminated film of an AuZnNi layer and an Au layer. The lower electrode 46 is a laminated film of an AuGeNi layer and an Au layer.

  The substrate and the layer around the active layer 41 have a refractive index lower than that of the active layer 41. Therefore, the part adjacent to the active layer 41 among the substrate and the layer functions as an optical confinement layer. The second optical waveguide 22 is constituted by the active layer 41 and the surrounding optical confinement layer. Current is injected into the active layer 41 by the upper electrode 45 and the lower electrode 46. Since the p-InP layer 47 and the n-InP layer 48 are present, current is selectively injected into the active layer 41.

  In this example, the entire second optical waveguide 22 is shown as an optical amplification region. However, a part of the second optical waveguide 22 may not be an optical amplification region.

  FIG. 4B shows the side surface 20s of the side surface of the second substrate 20 where the two end surfaces of the second optical waveguide 22 are exposed. The first end portion 22 m and the second end portion 22 n of the first optical waveguide 22 exist on the side surface 20 s side of the second substrate 20. The side surface 20s is formed by cleaving the substrate on which the semiconductor optical amplifier 40 is formed. An antireflection film (not shown) is formed so as to cover the first end 22m and the second end 22n.

  In the optical gyro element 100, the side surface 10s of the first substrate 10 and the side surface 20s of the second substrate 20 face each other. As a result, the first end portion 11m of the first optical waveguide 11 and the first end portion 22m of the second optical waveguide 22 are brought into contact with each other and coupled. In addition, the second end portion 11n of the first optical waveguide 11 and the second end portion 22n of the second optical waveguide 22 are abutted and coupled to each other. The first optical waveguide 11 and the semiconductor optical amplifier 40 constitute one ring laser.

  FIG. 5 schematically shows the arrangement of the first optical waveguide 11 and the second optical waveguide 22 in the vicinity of the side surface 10s and the side surface 20s. The optical axes at the two ends of the first optical waveguide 11 are inclined by an angle α with respect to the direction perpendicular to the side surface 10s. Further, the optical axes at the two end portions of the second optical waveguide 22 are inclined by an angle β with respect to the direction perpendicular to the side surface 20s. The angles α and β are determined in consideration of the effective refractive indexes of the first optical waveguide 11 and the second optical waveguide 22. When the effective refractive index of the second optical waveguide 22 is larger than the effective refractive index of the first optical waveguide 11, α> β.

  The function of the optical gyro element 100 will be described with reference to FIG. When a current is injected into the active layer of the semiconductor optical amplifier 40, light is generated. The generated light travels clockwise and counterclockwise along the annular optical path 50. This light is amplified in the semiconductor optical amplifier 40. When the current injected into the active layer exceeds the threshold value, the first laser light L1 propagating clockwise in the optical path 50 and the second laser light L2 propagating counterclockwise in the optical path 50 are excited.

  Part of the first laser light L 1 and the second laser light L 2 propagates to the third optical waveguide 13 in the optical coupler 51. In addition, a part of the first laser light L 1 traveling in the third optical waveguide 13 propagates to the adjacent third optical waveguide 13 in the optical coupler 52. As a result, the first laser beam L1 and the second laser beam L2 are superimposed and enter the photodiode 31. When there is a difference between the frequency of the first laser beam L1 and the frequency of the second laser beam L2, the photodiode 31 detects a beat signal based on the frequency difference between the two.

  Note that the third optical waveguide 13 may be replaced with two optical waveguides. FIG. 7 shows an arrangement of optical waveguides for an example of such an optical gyro element. The optical gyro element shown in FIG. 7 includes optical waveguides 71 and 72 formed on the first substrate 10. A part of the optical waveguide 71 is close to the first optical waveguide 11. A portion where the optical waveguide 71 and the first optical waveguide 11 are close to each other functions as an optical coupler 71a. A part of the optical waveguide 72 is close to the first optical waveguide 11. A portion where the optical waveguide 72 and the first optical waveguide 11 are close to each other functions as an optical coupler 72a. Further, a part of the optical waveguide 71 and a part of the optical waveguide 72 are close to each other so as to be parallel to each other. This portion functions as the optical coupler 71b. In the optical coupler 71a, a part of the first laser light L1 propagates to the optical waveguide 71. In the optical coupler 72 a, part of the second laser light L <b> 2 moves to the optical waveguide 72. In the optical coupler 71 b, a part of the second laser light L <b> 2 moves to the optical waveguide 71. As a result, the first laser beam L1 and the second laser beam L2 are superimposed and received by the photodiode 31.

  An example of a method for manufacturing the optical gyro element 100 will be described below. In the optical gyro element 100, the semiconductor optical amplifier 40, the first optical waveguide 11, and the photodiode 31 are formed on different substrates. Therefore, after forming each of these, it is necessary to arrange them accurately on the mounting substrate.

  First, as shown in FIG. 8A, a mounting substrate 70 on which pad electrodes 81 and 82 are formed is prepared. The mounting substrate 70 is preferably a substrate made of a material having a thermal expansion coefficient close to that of the semiconductor optical amplifier 40. Examples of the mounting substrate 70 include an AlN substrate, a quartz substrate, and a silicon substrate. Can be used.

  Next, the first substrate 10 on which the first and third optical waveguides 11 and 13 are formed is formed. As shown in FIG. 9, the first substrate 10 is formed by forming the first and third optical waveguides 11 and 13 longer and then polishing the side surfaces to the lines AA and BB. It is preferable to do. At this time, alignment marks 91 and 93 for aligning the semiconductor optical amplifier 40 and the photodiode 31 are formed on the surface of the upper clad layer 15. Also, the semiconductor optical amplifier 40 and the photodiode 31 are formed.

  Next, as shown in FIG. 8B, the first substrate 10 on which the first and third optical waveguides 11 and 13 are formed is bonded onto the mounting substrate 70. The first substrate 10 is bonded to the mounting substrate 70 with, for example, a UV curable adhesive for optical components.

  Next, as shown in FIG. 8C, the semiconductor optical amplifier 40 is bonded onto the mounting substrate 70. The semiconductor optical amplifier 40 is positioned accurately on the mounting substrate 70 so that the two ends of the second optical waveguide 22 and the two ends of the first optical waveguide 11 are optically coupled. Glued. At this time, the pad electrode 81 on the mounting substrate 70 and the lower electrode 46 of the semiconductor optical amplifier 40 are connected. For example, the semiconductor optical amplifier 40 is mounted on the mounting substrate 70 using a gold-tin bonding technique.

  An alignment mark is used to accurately position and mount the semiconductor optical amplifier 40. Specifically, as shown in FIG. 10, an alignment mark 91 is formed on the surface of the upper cladding layer 15 on the first substrate 10, and an alignment mark 92 is formed on the surface of the upper electrode 45 of the semiconductor optical amplifier 40. . By arranging the semiconductor optical amplifier 40 so that the alignment marks coincide with each other, the semiconductor optical amplifier can be accurately mounted in the horizontal direction. In addition, accurate vertical arrangement can be performed by adjusting the thickness of the pad electrode, the thickness of the substrate, the thickness of each layer constituting the optical waveguide, and the like.

  Next, as illustrated in FIG. 8D, the photodiode 31 is mounted on the mounting substrate 70. The photodiode 31 is mounted so that the pad electrode 82 and the lower electrode of the photodiode 31 are connected. The photodiode 31 is mounted with accurate positioning so that the laser beam emitted from the third optical waveguide 13 can be received. The photodiode 31 is also positioned using the alignment mark. Specifically, as shown in FIG. 10, an alignment mark 93 is formed on the surface of the upper cladding layer 15, and an alignment mark 94 is formed on the surface of the photodiode 31. Then, by arranging the photodiodes 31 so that the alignment marks coincide with each other, the photodiodes 31 can be mounted accurately in the horizontal direction. Note that accurate vertical arrangement can be performed by adjusting the thickness of the pad electrode, the thickness of the substrate, the thickness of each layer constituting the optical waveguide and the photodiode, and the like.

  The present invention can be applied to an optical gyro. The optical gyro element of the present invention can be applied to various electronic devices that require detection of 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 optical gyro element 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 takes advantage of the small size and low power consumption, and can be used for a portable information terminal such as a mobile phone and a small personal computer, a toy, a camera, and the like.

It is a figure which shows typically the structure of an example about the optical gyro element of this invention. (A) Sectional drawing of 1st optical waveguide, (b) It is a figure which shows the side surface of the 1st board | substrate which the edge part of the 1st optical waveguide has exposed. It is a top view which shows arrangement | positioning of the 2nd optical waveguide contained in a semiconductor optical amplifier. (A) Partial sectional view of a semiconductor optical amplifier, and (b) A side view of a second substrate where an end of a second optical waveguide is exposed. It is a figure which shows typically the state of the coupling | bonding of a 1st optical waveguide and a 2nd optical waveguide. It is a figure which shows the function of the optical gyro element of this invention. It is a figure which shows typically the structure of an example about another example of the optical gyro element of this invention. It is process drawing which shows an example of the manufacturing method of the optical gyro element of this invention. It is a figure which shows an example of the method of forming an optical waveguide on the 1st board | substrate. It is a figure which shows typically an example of the method of arrangement | positioning of a semiconductor optical amplifier and a photodiode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical gyro element 10 1st board | substrate 10s Side surface of 1st board | substrate 11 1st optical waveguide 11m 1st edge part of 1st optical waveguide 11n 2nd edge part of 1st optical waveguide 13 3rd Optical waveguide 14 Core layer 15 Upper cladding layer 20 Second substrate 22 Second optical waveguide 22m First end 22n of second optical waveguide 22n Second end 20s of second optical waveguide 20s of second substrate Side 31 Photodiode (observation means)
40 Semiconductor optical amplifier 50 Annular optical path 51 Optical coupler (drawing means)
52 Optical coupler (superposition means: observation means)
70 mounting substrate 71, 72 optical waveguide (third optical waveguide)
91, 92, 93, 94 Alignment mark L1, L2 Laser light

Claims (3)

An optical gyro element for obtaining a rotational angular velocity from a frequency difference between first and second laser beams propagating in opposite directions along an annular optical path,
A first optical waveguide formed on the first substrate; a semiconductor optical amplifier formed on the second substrate; and a drawing means for extracting a part of the first and second laser beams from the annular optical path; An observation means for observing a frequency difference between the extracted first and second laser beams, and a mounting substrate,
The semiconductor optical amplifier includes a second optical waveguide, at least a part of which is an optical amplification region,
The first and second ends of the first optical waveguide are present on one side of the first substrate;
The first and second ends of the second optical waveguide are on one side of the second substrate;
The first end of the first optical waveguide and the first end of the second optical waveguide are coupled, and the second end of the first optical waveguide and the first end The first substrate and the semiconductor optical amplifier are arranged on the mounting substrate such that the second end of the second optical waveguide is coupled to the second optical waveguide;
An optical gyro element in which the annular optical path is formed by the first optical waveguide and the second optical waveguide.   The optical gyro element according to claim 1, wherein a surface of the mounting substrate is flat. The observation means includes at least one optical waveguide for superimposing the extracted first and second laser beams, and a light receiving element for observing the superimposed first and second laser beams,
The at least one optical waveguide is formed on the first substrate;
The optical gyro element according to claim 1, wherein the light receiving element is disposed on the mounting substrate.

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