JP2000193461A - Gyro and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow detecting a different voltage change for the same angular speed using each laser diode by providing a plurality of ring resonator type laser diodes with different sensitivity on a single substrate or in a single case. SOLUTION: Related to a ring resonator laser diode, the light is confined in an active layer and circulates while repeating total reflections on a wall surface, with a wavelength meeting a phase condition after a single circulation while within a gain band of the active layer oscillating under current injection. The fluctuation in voltage change detected by the same rotational motion differs for respective first, second, and third ring resonator type laser diodes 2, 3, and 4. In theory, any change in angular speed is detected with a single diode. However, the frequency component of voltage change is actually detected, so there exist an upper and lower limits for a detected angular speed depending on a circuit performance. Since a different frequency change is caused with a different diode diameter A1 even in the same rotational motion, a wide angular speed range is coped with by using diodes of a plurality of diameters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gyro. More specifically, the present invention relates to a gyro having a wide angular velocity detection range. Furthermore, the present invention relates to a semiconductor device having a ring resonator type laser diode.

[0002]

2. Description of the Related Art Conventionally, as a gyro used for detecting an angular velocity of a moving object, a mechanical gyro having a rotor and a vibrator and an optical gyro are known. In particular, the optical gyro is capable of instantaneous activation and has a wide dynamic range, and is thus bringing about innovation in the gyro technical field. The optical gyro includes a ring resonator type laser gyro, an optical fiber gyro, and a passive type ring resonator type gyro. Of these, the ring resonance type laser gyro using a gas laser was first developed, and has already been put to practical use in aircraft applications and the like. Recently, a compact and high-precision ring-resonant laser gyro has also been proposed.
No. 288556 is disclosed. In such an optical gyro, a semiconductor ring resonator type laser is formed on one substrate, and clockwise and counterclockwise lights output from the ring waveguide are detected by a single photodetector outside the ring resonator. Angular velocity is detected by detecting the beat signal.

FIG. 15 is a plan view of a ring resonator type laser gyro disclosed in Japanese Patent Application Laid-Open No. 5-288556 as viewed from above. 110 is a semiconductor substrate, 111 is a gain waveguide, 112 is a reflection surface, 113 and 114 are output surfaces, 11
Reference numerals 8 and 119 denote lights output from the output surfaces 113 and 114, 1
17 is a photodetector, 122 is an electrode. In the case of the gyro shown in FIG. 15, by injecting a current, laser oscillation light is generated in the gain waveguide 111 having the reflection surface 112, and the clockwise and counterclockwise light wavelengths differ depending on the angular velocity. Two output lights 118 and 119 (corresponding to clockwise and counterclockwise light, respectively) interfere on the detector 117, and the angular velocity is output from the electrode 123 as a voltage change.

[0004]

However, in the above-mentioned conventional example, the clock signal and the counterclockwise light traveling in the ring waveguide are extracted and interfered on the photodetector to detect the beat signal. Therefore, the element size becomes large. Further, there has been a demand for a gyro having higher detection sensitivity or a wider detection range of angular velocity.

[0005] An object of the present invention is to provide a gyro having a wide angular velocity detection range. Another object of the present invention is to provide a gyro that can detect angular velocity with high reliability and can be downsized.

[0006]

A gyro according to the present invention is a gyro having a ring resonator type laser diode and detecting a beat signal generated by rotation, wherein a plurality of the laser diodes are provided on the same substrate. It is characterized by being provided.

Further, the present invention is characterized in that the active layers constituting the laser diode are arranged separately from each other.

Further, the present invention is characterized in that the size of the plurality of laser diodes or the type of the active layer constituting the laser is two or more.

The gyro according to the present invention is characterized in that the plurality of laser diodes are formed on the same surface of the same substrate.

Further, the present invention is characterized in that a beat signal is detected as a voltage applied to the laser diode, or a change in current or impedance flowing through the laser diode. More specifically, it is characterized in that each frequency change is detected.

In the semiconductor device according to the present invention, when driven at a constant current, a ring resonator type laser diode in which a voltage changes between predetermined terminals according to the magnitude of the applied angular velocity is provided in one housing. And a plurality thereof.

Further, in the semiconductor device according to the present invention, when driven at a constant voltage, a ring resonator type laser diode in which a drive current changes in accordance with the magnitude of the applied angular velocity is provided in one housing. , Provided in plurality.

Further, the semiconductor device according to the present invention includes a ring resonator type laser diode which generates a voltage change according to the magnitude of the applied angular velocity when driven at a constant current.
A semiconductor device, wherein a plurality of semiconductor devices are provided over one substrate.

Further, the semiconductor device according to the present invention includes a ring resonator type laser diode in which a driving current changes in accordance with the magnitude of the applied angular velocity when driven at a constant voltage, on one substrate. It is characterized in that a plurality are provided.

In a gyro in which a plurality of ring resonator type laser diodes are provided on one substrate as in the present invention, the angular velocity detection sensitivity of each laser diode can be different. A gyro having a wider angular velocity detection range than before can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and operation of a gyro according to the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view showing an example of an element constituting a gyro according to the present invention.
A case where a plurality of ring resonator type laser diodes are provided on one substrate is shown. In FIG. 1, reference numeral 1 denotes a semiconductor substrate, and reference numerals 2, 3, and 4 denote first, second, and third diameters formed on the front surface side of the semiconductor substrate 1 (the radius a _i is shown in the drawing). This is a ring resonator type laser diode. The first ring resonator type laser diode 2, the second ring resonator type laser diode 3, and the third ring resonator type laser diode 4 have different diameters. Here, the radii of the respective diodes are a ₁ , a It noted a _2, a _3.
Reference numeral 16 denotes a first electrode provided on the back surface side of the semiconductor substrate 1. Of course, the radii indicated by a ₁ , a ₂ , and a ₃ may be the same, or two or more values may be mixed. FIG. 1 shows three laser diodes, but two or four or more laser diodes may be used.

FIG. 2 is a schematic sectional view for explaining an example of the layer configuration of the ring resonator type laser diode shown in FIG. Each of the ring resonator type laser diodes 2, 3, and 4 in FIG. 1 shows a case where they are formed in the same layer configuration. That is, the configuration shown in FIG. 2 is the configuration of the first, second, and third ring resonator type laser diodes. In FIG. 2, 1 is a semiconductor substrate, 12 is a buffer layer (also serving as a cladding layer) formed on the surface of the semiconductor substrate 1, 13 is an active layer, 14 is a first cladding layer, 15
Is a cap layer, 16 is a first electrode formed on the back surface of the semiconductor substrate 1, and 17 is a second electrode formed on the cap layer 15.
Electrodes.

If a plurality of laser diodes are formed on the same substrate as shown in FIG. 1, the manufacturing process can be simplified.

In particular, in this embodiment, since a laser diode is formed on the same surface of the same substrate, a more simplified process can be constructed.

FIG. 3 is a perspective view showing an example of a gyro using the element shown in FIG. In order to use an element formed by the above-described steps, a current must be injected or a voltage must be applied, and thus, for example, the configuration shown in FIG. 3 is required. Hereinafter, description will be made focusing on the case of constant current driving.

In FIG. 3, reference numeral 20 denotes a stem on which a laser is mounted, 21 denotes a common electrode connected to the stem, 24 denotes a ring resonator type laser diode shown in FIG. 1, and 23 denotes a ring resonator type laser. An electrode 22 corresponding to each element of the diode 24, and a wire 22 connecting the electrode 23 and the ring resonator type laser diode 24.

The substrate side was used as a common electrode and bonded to the stem 21 by soldering, and the electrode on the cap layer side was connected to the electrode 23 by a wire 22. As shown in FIG. 3, the first electrode 16 and the second electrode 1 of each ring resonator type laser diode are connected while allowing current to flow through the element and performing current injection.
The change of the terminal voltage between 7 is detected. In addition, in order to perform current injection and voltage detection with the same electrode, the circuit shown in FIG. 4 including a capacitor and an inductance was used. Of course, the circuit configuration is not limited as long as the voltage can be detected. FIG. 4 shows only the electrical connection to the element, and the stem 20 and the wire 22 shown in FIG.
Etc. are omitted. With such a configuration, a current can be injected through the inductance, and a change in voltage between the first electrode 16 and the second electrode 17 can be detected via the capacitor.

Further, in the above-mentioned configuration, by providing a means for detecting a voltage change while injecting current into the ring resonator type laser diode, the means for detecting the voltage change can provide a terminal for monitoring the voltage change. Therefore, it is possible to easily connect a signal processing circuit to the monitor terminal. Of course, the means for detecting the voltage change may be individually connected to a plurality of ring resonator type laser diodes.

Hereinafter, the actual operation will be described.

In a ring resonator type laser diode,
The light is confined in the active layer 13 and circulates while repeating total reflection on the wall surface (in the present embodiment, the side surface of the cylinder). Wavelength (when current is injected into the active layer,
(Wavelength range indicating amplification) leads to oscillation by current injection.
In the laser diode, light propagates in a counterclockwise circuit. That is, the light circulates clockwise and counterclockwise in the active layer 13 (disk shape). pn
Rotational motion (angular velocity Ωrad / s) in the plane horizontal to the joint
Is added, the optical path length sensed by left-handed light and right-handed light changes, and the wavelength (frequency) of left-handed and right-handed light changes accordingly. Specifically, when subjected to clockwise rotation, the wavelength of clockwise light becomes longer, while the wavelength of counterclockwise light becomes shorter.

That is, in each of the ring resonator type laser diodes of the present embodiment, the angular velocity Ω (rad /
s), the first electrode 16 and the second electrode 1 of each device
7 is a beat frequency (Δ
ω).

Δω _i = (2πa _i / λ _i ) Ω Here, i = 1, 2, and 3. When detecting a voltage change, the current was set to a constant current injection operation, and no voltage change was detected when the angular velocity Ω was 0. If there are three ring resonator type laser diodes and their diameters _ai are different, the oscillation wavelengths will also be different. It should be noted that in the above equation, the wavelength is expressed as λ _i.

The fluctuation of the voltage change detected by the same rotational movement (Ωrad / s) differs between the first, second and third ring resonator type laser diodes 2, 3 and 4.

In principle, if there is one ring resonator type laser diode, any change in angular velocity can be detected.

However, since the frequency component of the voltage change is actually detected, the detected angular velocity has an upper limit and a lower limit depending on the performance of the detection circuit. As described above, even if the rotational motion is the same, if the diameter (a _i ) of the ring resonator type laser diode is different, the frequency changes differently. Therefore, by using a ring resonator type laser diode having a plurality of diameters, In the bandwidth of an electric circuit (a part for detecting a frequency component of a voltage), it is possible to cope with a wider angular velocity range than when detecting with a single ring resonator type laser diode.

FIG. 5 is a graph showing the relationship between the angular velocity Ω and the beat frequency Δω, and shows the case where the diameter (a _i ) of the ring resonator type laser diode is different. As can be seen from the above equation, the angular velocity Ω and the beat frequency Δω are in a proportional relationship. For example, when only a ring resonator type laser diode having a diameter of a ₂ is used, the frequency range that can be detected by the detection circuit is A. If there is only one ring resonator type laser diode having a diameter a ₂ , only the angular velocity range B in FIG. 5 can be detected. In contrast, a gyro having a plurality of ring resonator type laser diodes as in the present invention can detect the angular velocity range indicated by C in FIG. A wider angular velocity range can be detected than when a diode is used.

As described above, it is desirable that the gyro is constituted by a plurality of laser diodes having different ratios of the change of the beat frequency to the change of the angular velocity (ie, the inclination shown in FIG. 5). The laser diodes having different inclinations are realized by changing their sizes. The size here refers to, for example, the diameter of a laser diode.

When there are a plurality of ring resonator type laser diodes having the same diameter, it is preferable to improve the reliability of angular velocity detection by averaging the angular velocities detected from the respective laser diodes. .

However, even if the diameter is the same, the type of the active layer is made different and the oscillation frequency is changed, so that the angular velocity can be detected in a wide range as in the case where the laser diodes having different diameters are arranged.

Further, the configurations of the active layers constituting the plurality of ring resonator type laser diodes are made different from each other, and a configuration having different oscillation wavelengths and a configuration having the same oscillation wavelength are set to desired settings. In addition, it can be appropriately manufactured.

When different ring resonator type laser diodes having different active layers have different oscillation wavelengths, ring resonator type laser diodes having different detection sensitivities with different angular velocities on the same substrate. Can be formed. In this case, since the diameters of the individual ring resonator type laser diodes may be the same, manufacturing conditions in, for example, a deposition step and an etching step of a thin film constituting the diode become easy.

When different ring resonator type laser diodes having different active layers have the same oscillation wavelength, the angular velocities can be detected by a plurality of laser diodes, so that a highly reliable optical gyro can be obtained. Can be In this case, by making the diameters of the individual ring resonator type laser diodes different from each other, it is also possible to form ring resonance type laser diodes having detection sensitivities with different angular velocities on the same substrate.

In this embodiment, each ring resonator type laser diode is driven at a constant current, and the voltage applied to the laser diode is detected. However, the current value of the constant current is the same for each element. Or may be different. It is also possible to intentionally adjust the ratio of the frequency change (Δω) of the voltage to the same angular velocity (Ω) (that is, the proportional coefficient) by changing the internal oscillation wavelength as a different injection current amount. Of course, instead of the constant current drive, each element may be separated and configured to be a constant voltage drive, and the beat may be detected by a change in current flowing through the ring laser diode. It is also possible to drive each of the plurality of laser diodes with a different voltage. Further, the angular velocity can be obtained by driving at a constant voltage or a constant current and directly detecting a change in the impedance of the laser diode with an impedance meter.

In the present embodiment, the plurality of laser diodes have been described as having a circular shape as an example. However, a polygon such as a triangle or a quadrangle, or a cylindrical structure as shown in FIG. And a waveguide-type ring laser having the following. FIG. 6 is a view of the laser diode as viewed from above, and FIG. 7 shows the ring laser 100 of FIG.
FIG. 3 shows a cross-sectional view at A ′. In addition, 1 is a substrate,
16 and 17 are electrodes, 15 is a cap layer, 14 and 72
Is a cladding layer, and 73 and 74 are light guide layers, but the configuration of the laser diode is not limited to this.

Although only one laser diode is shown in FIGS. 6 and 7, actually, a gyro is constituted by a plurality of laser diodes, that is, two or more laser diodes, so that the angular velocity detection range can be expanded and the sensitivity can be increased. Improve.

An example of a specific configuration of a ring resonator type laser diode is shown.

In FIG. 1, for example, n-type InP is used as the semiconductor substrate 1, a buffer layer made of n-type InP is provided on the surface thereof, InGaAsP is used as the active layer 13, p-type InP is used as the first cladding layer, and the cap layer 15 is used as the cap layer 15. p-type InGaAs can be used.

Note that changes in terminal voltages may be detected from terminals individually connected to the plurality of laser diodes, and one of the plurality of laser diodes may be driven at a constant current. A voltage change accompanying rotation may be detected, and another may be driven at a constant voltage to detect a current change. Of course, the impedance change may be detected.
Various kinds of change detection means may be combined.

As shown in FIG. 1, the first, second, and third ring resonator type laser diodes 2, 3, and 4 have their active layers constituting the laser diodes separated from each other. . It is preferable to arrange them at intervals so as not to couple light with each other. In this case, to avoid the influence of evanescent light, approximately 5 μm
m or more, more preferably, 15 μm or more. Further, an absorber may be formed between each ring resonator type laser diode. The absorber makes it possible to reduce the mutual influence of leaked light from the ring resonator type laser diode. Note that a shielding film may be used as the absorber.

The active layer 13 may be constituted by a light guide layer and an active region forming a population inversion. The active region has, for example, a quantum well structure (for example, quantum well number 3).
Here, a 6-nm-thick non-doped I
nGaAs is formed on the barrier layer by using InGaAsP having a thickness of 15 nm.
(A wavelength of 1.3 μm corresponding to the band gap) can be used.

In the light guide layer, non-doped InGaAsP (wavelength 1.15 μm corresponding to a band gap) having a thickness of about 0.05 μm is formed on both sides of the active region.
As described above, a configuration in which the active region is sandwiched between the two light guide layers can be adopted.

The element having the above-described layer structure is formed by a conventional technique for forming a semiconductor laser, that is, a crystal growth technique, a film forming technique such as a dielectric material (for example, SiN _x , S
iO ₂ ), semiconductor processing technology (photolithography technology, etching technology, and the like), electrode formation technology, and the like. For example, the manufacturing procedure is as follows.

On a semiconductor substrate, a crystal is grown by an existing crystal growth technique such as MOCVD or MBE so as to have a layer structure shown in FIG. 2 to produce an original wafer.

An etching mask is formed on the original wafer by using a photolithography technique (a resist may be used as a mask, SiN _x may be used as a mask, or both a resist and SiN _x may be used as a mask. May be used together).

Based on this mask, etching (dry etching, wet etching, or
By performing both dry etching and wet etching, the original wafer becomes cylindrical (of course, triangular prism,
A polygonal columnar structure such as a quadrangular prism or hexagonal prism may be used. ) To obtain a substrate processed.

Electrodes are formed on the semiconductor substrate 1 side and the cap layer side.

Thereafter, the electrodes are alloyed by a heat treatment to complete the device shown in FIG. 1 having a plurality of ring resonator type laser diodes having the layer structure of FIG.

The semiconductor substrate 1 used in the above-mentioned manufacturing procedure may be polished as required. Alternatively, reactive ion beam etching using chlorine gas or bromine gas can be used.

Examples of the material of the active layer applicable to the present invention include GaAs, InP, ZnSe, and AlGaAs.
s, InGaAsP, InGaAlP, InGaAs
P, GaAsP, InGaAsSb, AlGaAsS
b, InAsSbP, PbSnTe, GaN, GaAl
N, InGaN, InAlGaN, GaInP, GaI
Examples include nAs and SiGe.

As a combination of the active layer and the cladding layer, for example, PbSnTe (active layer) / PbSeTe
(Cladding layer), PbSnSeTe (active layer) / PbS
eTe (cladding layer), PbEuSeTe (active layer) /
PbEuSeTe, PbEuSeTe (active layer) / Pb
Te (cladding layer), InGaAsSb (active layer) / G
aSb (cladding layer), AlInAsSb (active layer) /
GaSb (cladding layer), InGaAsP (active layer) /
InP (cladding layer), AlGaAs (active layer) / Al
GaAs (cladding layer), AlGaInP (active layer) /
AlGaInP (cladding layer) or the like can be used.

Further, the structure of the semiconductor laser is not limited to the active layer having a bulk structure, but may be a single quantum well structure (SQ).
W) and a multiple quantum well structure (MQW).

When a quantum well laser is used, it is also preferable to adopt a strained quantum well structure. For example, an InGaAsP quantum well 8 having a compression strain of about 1%
The active layer is formed by the layer and the barrier layer of InGaAsP.

Of course, an MIS structure can also be used.

The substrate may be any substrate on which a desired material can be grown.
Compound semiconductors such as nP substrate, GaSb substrate, InAs substrate, PbTe substrate, GaN substrate, ZnSe substrate, ZnS substrate, SiC substrate, 4H-SiC substrate, 6H-S
An iC substrate, a sapphire substrate, a silicon substrate, an SOI substrate, or the like can be used.

For forming an active layer of a semiconductor laser or the like, liquid phase epitaxy (LPE method), molecular beam epitaxy (MB
E method), metal organic chemical vapor deposition (MOCVD, MOVP)
E method), atomic layer growth method (ALE method), metalorganic molecular beam epitaxy (MOMBE), chemical beam epitaxy (CB)
E) can be used.

The anode electrode was made of Cr / A
u, Ti / Pt / Au, AuZn / Ti / Pt / Au or the like can be used. AuG is used as the cathode electrode.
e / Ni / Au or AuSn / Mo / Au can be used.

Although the material of the composition constituting the laser diode and the like have been exemplified, the invention is not limited thereto as long as a gyro capable of exhibiting desired performance can be manufactured.

It is preferable to mount a semiconductor laser chip on a heat radiating material (heat sink) in order to prevent the laser diode from affecting the heat. Cu, Si, Si
C, AlN, diamond and the like can be used.
Of course, it is not limited to these. Further, if necessary, a Peltier element can be used for temperature control.

In order to ensure that the semiconductor laser becomes a total reflection surface or to prevent deterioration, an insulating film (coating film) is provided on the side surface (side surface of the region where light exists) of the semiconductor laser. The formation is also preferable. As the coating material, SiO2, Si
An insulating film such as N, Al2O3, Si3N4, amorphous silicon (α-Si), or the like can be used.

A gyro can be formed by combining the semiconductor device according to the present invention with an optical fiber gyro or a vibrating gyro.

(Second Embodiment) FIG. 8 is a perspective view showing another example of an element constituting a gyro according to the present invention, in which ring resonator type laser diodes having different radii are arranged coaxially. The following shows the case. In FIG. 8, the first, second, and third ring resonator type laser diodes are designated as 31, 32, and 33, respectively, from the smallest ring diameter.

FIG. 9 is a schematic cross-sectional view illustrating an example of the layer configuration of a plurality of ring resonator type laser diodes 30 arranged coaxially as shown in FIG. The basic structure is the same as in the first embodiment (FIG. 2). That is, in FIG. 9, 1 is a semiconductor substrate, 12 is a buffer layer (also serving as a cladding layer) formed on the surface of the semiconductor substrate 1, 1.
Reference numeral 3 denotes an active layer, 14 denotes a first cladding layer, 15 denotes a cap layer, 16 denotes a first electrode formed on the back surface of the semiconductor substrate 1, and 17 denotes a second electrode formed on the cap layer 15.

As shown in FIG. 9, it is desirable that the first, second, and third ring resonator type laser diodes 31, 32, and 33 be spaced apart from each other so that light does not couple with each other. Specifically, it is 5 μm or more, preferably 15 μm or more.

The active layer 13 is composed of the light guide layer and the active region forming the population inversion, but is not limited to this.

By electrically connecting the elements having such a configuration in the same manner as in the first embodiment (wiring in FIG. 4),
Each ring resonator type laser diode has an angular velocity Ω (r
ad / s) (the beat signal Δ
ω) can be detected.

The operation of the ring resonator type laser diode is the same as that of the first embodiment, and therefore will be briefly described here.

As shown in the first embodiment, the element itself is driven at a constant current and detects a change in voltage between terminals. In each ring resonator type laser diode, in the steady state, left-handed and right-handed light are independently formed, and both have the same oscillation frequency. Angular velocity (Ωra
d / s), the wavelength of clockwise light and the wavelength of counterclockwise light change as described in the first embodiment, respectively.
The voltage between the terminals is equal to the frequency (Δ
ω). By measuring this frequency, the angular velocity can be known. Of course, constant voltage drive,
A change in current flowing through the laser diode may be detected, or a change in impedance may be directly measured.

In the case of the configuration of the present embodiment (FIGS. 8 and 9), in addition to the features described in the first embodiment (the range of angular velocity that can be detected is widened by the combination with the electric circuit to be detected), furthermore, Further downsizing of the element can be achieved.

In FIG. 9, for example, 1 is an n-type InP substrate, 12 is a buffer layer made of n-type InP, 14 is a first cladding layer made of p-type InP, and 15 is p-type InGaAs.
s can be formed with a cap layer.

The active region has, for example, a quantum well structure (the number of quantum wells is 3). The well layer is made of non-doped InGaAs with a thickness of 6 nm, and the barrier layer is made of InGa with a thickness of 15 nm.
AsP (wavelength 1.3 μm corresponding to the band gap) can also be used. The light guide layer is 0.05 μm thick
A moderately non-doped InGaAsP (wavelength 1.15 μm corresponding to the band gap) is formed on both sides of the active region. The active layer 13 may be configured such that the active region is sandwiched between the two light guide layers. Of course, the structure of this active layer may be bulk.

It goes without saying that the materials shown in the first embodiment can be used for the material of the active layer and the substrate, or for the method of forming the laser diode and the electrodes.

(Third Embodiment) FIG. 10 is a perspective view showing another example of the element constituting the gyro according to the present invention. The configuration shown in FIG. 8 (a ring resonator type laser diode having a different radius) is used. The second embodiment differs from the second embodiment in that an arrangement for reducing optical coupling between ring resonator type laser diodes is incorporated. That is, in the configuration shown in FIG. 10, ring resonator type laser diodes are vertically stacked on the semiconductor substrate 1.

In FIG. 10, 41 is a first ring resonator type laser diode, 42 is a second ring resonator type laser diode, and 43 is a third ring resonator type laser diode. With such a configuration, it is possible to prevent light leakage from the side surface of the ring from being coupled to another ring resonator type laser diode and disturbing the state.

In order to make such a configuration, it is necessary to have a structure that can inject current into each element and detect a voltage change. FIG. 11 is a schematic cross-sectional view illustrating an example of a layer configuration of a plurality of ring resonator type laser diodes arranged coaxially and stacked as shown in FIG.

In FIG. 10, each ring resonator type laser diode has substantially the same layer configuration as the first and second embodiments, but is not limited to this.
The difference is that a reverse bias layer is added to electrically isolate each element.

The basic structure can be the same as in the first and second embodiments. In FIG. 11, 1 is a semiconductor substrate, 121 is a buffer layer (also serving as a cladding layer), 13
1 is an active layer, 141 is a first cladding layer, 151 is a cap layer, and 161, 162 and 163 are formed on portions corresponding to the substrates of the respective ring resonator type laser diodes.
The electrodes 171, 172, 173 are second electrodes formed on the cap layers 151, 152, 153 of each ring resonator type laser diode.

161, 1, 121, 131, 141, 1
51, 171 constitute a first ring resonator type laser diode 41, and 162, 122, 132, 142, 15
2,172, the second ring resonator type laser diode 4
163, 133, 143, 153, 17
3 constitutes a third ring resonator type laser diode 43. Reference numerals 181 and 182 denote first and second reverse bias layers. The semiconductor substrate is n-type InP, the buffer layer is n-type InP, and the first cladding layer is p-type IP.
nP and p-type InGaAs can be used as the cap layer. Of course, those exemplified in the first embodiment can also be used.

The reverse bias layers 181 and 182 are made of pn
For example, the cap layer 151 of the first ring resonator type laser diode 41 and the buffer layer 122 of the second ring resonator type laser diode 42 are formed.
Between the pn junction of the reverse bias layer 181 and the cap layer 151 of the first ring resonator type laser diode 41 and the second ring resonator type. The current is prevented from flowing between the laser diode 42 and the buffer layer 122.

As described above, the electrical isolation between the ring resonator type laser diodes is achieved by the reverse bias layer 18.
1, 182. Further, in order to inject a current or apply a voltage to each ring resonator type laser diode, a step is provided so that a wire can be connected between an n-type cladding layer and a p-type cap layer.

As shown in this embodiment, by forming a plurality of ring resonator type laser diodes coaxially with each other, the substrate area required for installing the laser diodes can be reduced, so that the size of the device can be reduced. In addition, the power consumption of the ring resonator type laser diode having a large diameter can be reduced.

(Fourth Embodiment) FIG. 12 is a perspective view showing another example of the element constituting the gyro according to the present invention. When a plurality of ring resonator type laser diodes are provided on the same surface of one substrate, an active layer constituting each ring resonator type laser diode is provided with a peak wavelength of gain (a wavelength having the largest gain). The difference from the first embodiment lies in the point that it is formed differently.

In this embodiment, the case where each ring resonator type laser diode has the same ring diameter and a different internal wavelength will be described with reference to FIG. That is, in FIG. 12, reference numeral 1 denotes a semiconductor substrate;
Reference numerals 3 and 54 denote first, second, and third ring resonator type laser diodes formed on the semiconductor substrate 1 and having different ring diameters (a _i , i = 1, 2, 3 shown in the figure). However, in the present embodiment, the first ring resonator type laser diode 52 and the second ring resonator type laser diode 5
3, the third ring resonator type laser diode 54 is used as having the same ring size, here, the radius a ₁
And

FIG. 13 is a schematic sectional view for explaining an example of the layer structure of the ring resonator type laser diode shown in FIG. The ring resonator type laser diodes 52, 53, 54 of FIG. 12 are formed in the same layer configuration except for the active layer, respectively, so that the configuration shown in FIG.
The second and third ring resonator type laser diodes are configured. In FIG. 13, 1 is a semiconductor substrate, 12 is a buffer layer (also serving as a cladding layer) formed on the surface of the semiconductor substrate 1, and 133i is an active layer (i = 1, 2, 3 for the first, second, and third layers, respectively). An active layer corresponding to a ring resonator type laser diode), a first cladding layer, 15
Is a cap layer, 16 is a first electrode formed on the back surface of the semiconductor substrate 1, and 17 is a second electrode formed on the cap layer 15.
Electrodes.

As shown in FIG. 12, first, second and third ring resonator type laser diodes 52, 53 and 54 are
It is desirable to arrange them at intervals so as not to combine light with each other. Further, an absorber may be formed between each ring resonator type laser diode. The absorber makes it possible to reduce the mutual influence of leaked light from the ring resonator type laser diode. For example, n-type InP can be used as a semiconductor substrate, n-type InP can be used as a buffer layer, p-type InP can be used as a first cladding layer, and p-type InGaAs can be used as a cap layer. Of course, other than those described in the first embodiment can be used.

The active layer 133i was constituted by a light guide layer and an active region forming a population inversion. The active area is
For example, a quantum well structure can be used. here,
First, second, and third ring resonator type laser diodes 5
The active layers 133i corresponding to 2, 53 and 54 have gain peak wavelengths of λ ₁ μm, λ ₂ μm and λ ₃ μm, respectively.
Quantum wells such that Where λ ₁ ≠ λ ₂ , λ ₁ ≠
λ ₃ . λ ₁ = 1.55, λ ₂ = 1.4, λ ₃ = 1.3
It is. The light guide layer was formed of non-doped InGaAsP (wavelength corresponding to a band gap of 1.15 μm) having a thickness of about 0.05 μm on both sides of the active region. That is, the configuration in which the active region is sandwiched between the two light guide layers,
In FIG. 11, it is represented as an active layer 133i.

When an element having such a configuration is actually used, the configuration shown in FIG. 3 is used in the first embodiment, and electrical connection is performed using the method shown in FIG.
With this configuration, a constant current is injected through an inductance, and the first electrode 16 is connected through a capacitor.
A change in the voltage between the second electrode 17 and the second electrode 17 can be detected. The operation can be performed by detecting a voltage change under the influence of the angular velocity (Ω), as described in the first embodiment. The change in voltage (Δω) follows the equation described in the first embodiment. As can be seen from this equation, for the same angular velocity (Ω), even if the radius of the ring is different,
Even if the wavelength is different, a different beat frequency (Δω) can be output. That is, since the active layer 133i is different for each ring resonator type laser diode having the same diameter, the same angular velocity (Ω) can be made to correspond to a frequency change (Δω) of a different voltage.

As a result, even when the diameter of the ring resonator type laser diode is limited (the limit may be larger or smaller), the wavelength of each ring resonator type laser diode is adjusted. Thus, the same effect as in the first embodiment can be obtained.

(Fifth Embodiment) In the fourth embodiment, an example was shown in which the inside wavelength was made different with the same ring diameter in the element configuration shown in FIGS. 12 and 13. The same effect can be obtained even if the gyro is constituted by a plurality of ring resonator type laser diodes having the same wavelength and different ring diameters.

In this case, it can be realized by changing the orbital distance of the ring at an integer multiple of the wavelength, changing the current injection condition for each ring resonator type laser diode, or changing the operating temperature of the element.

Such a configuration has two variables that affect the proportional coefficient between the angular velocity (Ω) and the change in voltage (Δω) shown in the first embodiment, that is, one of the wavelength and the ring diameter. Means that only one of them is changed, and there is an effect that the frequency component (Δω) of the voltage change obtained from the predetermined angular velocity (Ω) can be fixed at the time of manufacturing the element. If such control is not performed, the relationship between the angular velocity (Ω) and the beat frequency (Δω) can be known before the device is operated, even when an element whose wavelength and ring diameter are changed at once is manufactured.

(Sixth Embodiment) FIG. 14 is a perspective view showing an example of an optical gyro according to the present invention. When the optical gyro is driven at a constant current, a predetermined value is set according to the magnitude of the applied angular velocity. A case where a plurality of ring resonator type laser diodes in which a voltage change occurs between terminals is provided in one housing is shown.

In FIG. 14, reference numeral 20 denotes a stem used as a housing, 21 denotes a common electrode connected to the stem 20, 6
1, 62 and 63 are ring resonator type laser diodes having different ring diameters, 23 is an electrode corresponding to each element of the ring resonator type laser diodes 61, 62 and 63, and 22 is each electrode 23 and the ring resonator type. These wires connect the laser diodes 61, 62, and 63.

Here, the individual configurations of the ring resonator type laser diodes 61, 62 and 63 having different ring diameters are as follows.
The same configuration (FIG. 2) as the ring resonator type laser diode shown in the first embodiment can be used.

In the above configuration, the substrate side of each of the ring resonator type laser diodes 61, 62 and 63 is used as a common electrode and individually bonded to the stem 20 by soldering.
The electrodes on the cap layer side of each of the ring resonance type laser diodes 61, 62, 63 are connected to individual electrodes 23 by respective wires 22.

As shown in FIG. 14, the elements are connected so that a current can flow, and a change in voltage between the electrodes of each ring resonator type laser diode is detected while current is injected. Since the current injection and the voltage detection are performed by the same electrode, a device including a capacitor and an inductance as shown in FIG. 4 can be used.

The operation is the same as in the first embodiment.
That is, each ring resonator type laser diode is driven by constant current, and the frequency (wavelength) of clockwise light and counterclockwise light slightly changes in the element according to the angular velocity (Ω). The voltage changes. By detecting this voltage change, the magnitude of the angular velocity can be measured.

According to the above configuration, a plurality of ring resonator type laser diodes are connected to one housing (for example, a stem,
Case) can be implemented in a hybrid manner. At this time, since each ring resonator type laser diode has a different ring diameter, for example, it is possible to have different detection sensitivities of angular velocity,
A gyro having a wider detection sensitivity than before can be obtained.

In the above description, the case where the stem is used as the housing is exemplified. However, the housing according to the present invention may have any form as long as a plurality of ring resonator type laser diodes can be hybrid-mounted. However, for example, a case or the like may be used.

In the above description, the ring resonator type laser diodes having different ring diameters have been described. However, as described above, the configuration of the active layer of each ring resonator type laser diode is different from each other, and It goes without saying that the same effect can be expected even if the oscillation wavelength is the same.

In the above-described five embodiments, an example in which an InP-based material is used as a material for forming a laser diode has been described. However, any other material that can form a semiconductor laser such as GaAs can be used. May be.

Further, in the first and third to fifth embodiments, the disk resonator type laser diode is shown as a disk-shaped laser diode, but it is needless to say that the ring-shaped laser diode shown in the second embodiment is used. May be applied. Furthermore, the route does not have to be within the circle as long as it is orbiting.

In the above-described embodiment, the case where the constant current drive is performed to detect a voltage change according to the angular velocity applied to the element has been described. However, in the present element, the element impedance changes according to the angular velocity applied to the element during driving. Can be treated as something. Therefore, for example, by applying a constant voltage operation and detecting a change in current, a change in angular velocity can be detected,
In addition, it is possible to know the impedance change by a method capable of knowing the impedance change, and also to know the angular velocity change.

The method of driving the plurality of ring resonator type laser diodes and detecting the angular velocity are not limited to any one type, but may be different from each other.

[0110]

As described above, according to the present invention,
By providing a plurality of ring resonator type laser diodes with different sensitivities on one substrate or in one housing, different voltage changes can be obtained for the same angular velocity using each ring resonator type laser diode. Since it is possible to detect the gyro, it is possible to provide a gyro having a wider angular velocity detection range as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an element constituting a gyro according to the present invention.

FIG. 2 is a schematic sectional view illustrating an example of a layer configuration of the ring resonator type laser diode shown in FIG.

FIG. 3 is a perspective view showing an example of a gyro using the element shown in FIG.

FIG. 4 is a diagram showing a circuit composed of a capacitor and an inductance, which is used for performing current injection and voltage detection on the same electrode.

FIG. 5 is a graph showing a relationship between an angular velocity Ω and a beat frequency Δω.

FIG. 6 is a top view of an example of a laser diode constituting the gyro according to the present invention.

FIG. 7 is a sectional view of the laser diode shown in FIG. 6;

FIG. 8 is a perspective view showing another example of the element constituting the gyro according to the present invention.

9 is a schematic cross-sectional view illustrating an example of a layer configuration of a plurality of ring resonator type laser diodes arranged coaxially as shown in FIG.

FIG. 10 is a perspective view showing another example of the element constituting the gyro according to the present invention.

11 is a schematic cross-sectional view illustrating an example of a layer configuration of a plurality of ring resonator type laser diodes arranged coaxially and stacked as shown in FIG.

FIG. 12 is a perspective view showing another example of the element constituting the gyro according to the present invention.

13 is a schematic sectional view illustrating an example of a layer configuration of the ring resonator type laser diode illustrated in FIG.

FIG. 14 is a perspective view showing another example of the gyro according to the present invention, and when a constant current drive is performed, a voltage change occurs between predetermined terminals according to the magnitude of the applied angular velocity, and ring resonance is performed. The case where a plurality of container laser diodes are provided in one housing is shown.

FIG. 15 shows a conventional ring resonator type laser gyro;
It is the top view seen from above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 1st ring resonator type laser diode 3 2nd ring resonator type laser diode 4 3rd ring resonator type laser diode 12 Buffer layer (also clad layer) 13 Active layer, 14 1st clad layer 15 Cap layer Reference Signs List 16 first electrode 17 second electrode 20 stem 21 common electrode 22 wire 23 electrode 24 ring resonator type laser diode 31 first ring resonator type laser diode 32 second ring resonator type laser diode 33 third ring resonator type laser Diode 41 First ring resonator type laser diode 42 Second ring resonator type laser diode 43 Third ring resonator type laser diode 52 First ring resonator type laser diode 53 Second ring resonator type laser diode 54 Third phosphorus Light 122 electrode 123 electrode outputted from the laser beam 117 photodetector 118 119 output face 113,114 of the cavity laser diode 110 semiconductor substrate 111 gain waveguide 112 reflecting surfaces 113,114 of the light output surface 115 clockwise laser beam 116 counterclockwise

Claims (25)

[Claims] 1. A gyro having a ring resonator type laser diode and detecting a beat signal generated by rotation, wherein a plurality of the ring resonator type laser diodes are provided on the same substrate. A gyro that features. 2. The gyro according to claim 1, wherein the active layers constituting the ring resonator type laser diode are arranged separately from each other. 3. The gyro according to claim 1, wherein the ring resonator type laser diode is of a ring resonator type in which light propagates in a reciprocating circular shape. 4. The gyro according to claim 1, wherein the beat signal is detected as a change in a current flowing through the laser diode, a voltage applied to the laser diode, or a change in impedance of the laser diode. 5. The laser device according to claim 1, wherein the beat signal is detected as a frequency change of a terminal voltage provided in the laser diode, a frequency change of a current flowing through the terminal, or a frequency change of an impedance of the laser diode. Gyro. 6. The gyro according to claim 1, wherein the gyro is an optical gyro having the ring resonator type laser diode. 7. The gyro according to claim 1, wherein the plurality of laser diodes have two or more sizes. 8. The gyro according to claim 1, wherein the plurality of laser diodes have different sizes. 9. The gyro according to claim 1, wherein the plurality of laser diodes have two or more kinds of oscillation wavelengths. 10. The gyro according to claim 1, wherein the plurality of laser diodes are formed on the same surface of the same substrate. 11. The gyro according to claim 1, wherein the plurality of laser diodes are formed coaxially with each other. 12. The gyro according to claim 1, wherein the detection detects a frequency change of each terminal voltage from terminals individually connected to the plurality of laser diodes. 13. The gyro according to claim 1, wherein the active layers constituting the plurality of laser diodes have different compositions. 14. The gyro according to claim 1, wherein the active layers constituting the plurality of laser diodes have the same composition. 15. The gyro according to claim 1, wherein the plurality of laser diodes have different oscillation wavelengths. 16. A gyro according to claim 1, wherein the active layers constituting the plurality of laser diodes have different compositions and have different oscillation wavelengths. 17. The gyro according to claim 1, wherein the active layers constituting the plurality of laser diodes have different compositions and have the same oscillation wavelength. 18. The gyro according to claim 1, wherein the laser diodes have the same ring diameter. 19. The gyro according to claim 1, wherein the plurality of laser diodes are arranged at a distance of at least 15 μm. 20. A semiconductor device comprising: a plurality of ring resonator type laser diodes in which a voltage change occurs in accordance with the magnitude of an applied angular velocity when driven at a constant current; apparatus. 21. A plurality of ring-resonant laser diodes in which a drive current changes in accordance with the magnitude of an applied angular velocity when driven at a constant voltage, is provided in a single housing. Semiconductor device. 22. A plurality of ring resonator type laser diodes, on which voltage changes according to the magnitude of the applied angular velocity when driven at a constant current, are provided on a single substrate. Semiconductor device. 23. A single substrate is provided with a plurality of ring resonator type laser diodes in which a drive current changes in accordance with the magnitude of an applied angular velocity when driven at a constant voltage. Semiconductor device. 24. The ring resonator type laser diode is provided on the same surface of one substrate.
Alternatively, the semiconductor device according to item 23. 25. The semiconductor device according to claim 20, wherein the active layers constituting the ring resonator type laser diode are arranged separately from each other.