JP2001280973A - Three-dimensional ring laser device and gyrocompass using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional ring laser used for a gyro, etc., and capable of detecting directions. SOLUTION: Semiconductor ring lasers and electronic circuits in a prescribed pattern are formed on a plurality of crystalline planes crossing each other on a surface of a three-dimensional substrate such as a spherical Si substrate, thus providing a small-sized, three-dimensional ring laser having drive circuits and capable of processing data, and a gyrocompass using the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direction sensor, and more particularly to a three-dimensional ring laser device applied to a measuring instrument such as a gyro compass.

[0002]

2. Description of the Related Art Semiconductor ring laser devices have the potential of being compact and inexpensive to manufacture, and are therefore expected to be applied to measuring instruments, particularly gyro-compasses.

As a semiconductor ring laser, for example, J.
“Unidirectional operation of wavegu” by J. Liang et al.
ide ring lasers ”(Applied Physics Letters, 70 (10),
pp1192-1194 (1997)). FIG. 11 is a schematic diagram thereof. In the figure, 801 is a substrate, 802 is a ridge waveguide, 803 is a corner mirror, and 804 is a cleavage plane for extracting light. Reference numeral 805 denotes a tapered waveguide for giving a loss difference between the two ring laser modes. Here, carriers are injected from an electrode (not shown) on the ridge waveguide 802, and the light emitted from the active layer circulates while receiving the gain, and gives a gain exceeding the loss (increases the carrier injection amount). This causes oscillation in the ring laser mode.

[0004] A gyro compass is important as a key device as a posture control sensor for rotational movement of various structures. Vibratory gyros and gas laser gyros are used in aircraft and artificial satellites, but are expected to be actively used in new areas, such as game machines and medical equipment, as well as automobiles and industrial equipment in the future. .

[0005]

Since this semiconductor ring laser is formed by a so-called semiconductor process, it has advantages in that it is smaller than a general fiber gyro and does not require alignment of optical parts. On the other hand, there are the following problems.

[0006] First, when used as a rotating gyro,
In order to detect three directions, at least two axes in directions different from each other are required, and in order to realize this, it is necessary to mount a substrate constituting a semiconductor ring laser three-dimensionally ( This is a normal rotating gyro,
This is generally the case).

Second, it is necessary to separately provide a circuit for driving and signal processing as a rotating gyro by combining a semiconductor ring laser and each substrate, but in this case, a circuit is formed using a semiconductor process. This reduces the complexity of the process by half, necessitates complicated processes such as integration, circuit connection, and alignment between substrates, and makes it difficult to reduce the size.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a three-dimensional ring laser device in which a plurality of semiconductor ring laser structures are three-dimensionally incorporated into a single substrate, and It is to provide a gyro compass using this.

[0009]

Therefore, in the present invention,
On a plurality of crystal planes (planes) formed on a semiconductor substrate having a three-dimensional surface and intersecting with each other, an electronic circuit for configuring a semiconductor ring laser and driving or signal processing the semiconductor ring laser is provided. It is characterized by being integrated and formed on a semiconductor substrate.

In this case, as an embodiment of the present invention, the semiconductor substrate is made of a sphere, a polyhedron, or Si in a similar form, and the (111) plane and / or the (100) plane is formed on the semiconductor substrate. It is effective that the crystal plane is formed on an equivalent plane, and at least one semiconductor ring laser is formed on the crystal plane.

Further, some of the constituent materials of the semiconductor ring laser include GaNAs, GaInNAs, AlNAs,
III-VN semiconductor materials such as GaInNAsP (of group III and V compound materials,
The use of (a material containing (nitrogen)) is a preferred embodiment.

In the present invention, the gyro-compass constructed by using the above-described three-dimensional ring laser device detects a three-dimensional azimuth by the inclination of the semiconductor ring lasers formed on a plurality of crystal planes. It is configured to be.

As is apparent from the above configuration, the most significant feature of the present invention resides in that a plurality of ring lasers are integrated with an IC on the surface of a Si sphere. For this purpose, it is necessary to stack a compound semiconductor that is lattice-matched on a semiconductor substrate having a three-dimensional surface, for example, a Si spherical surface.

Generally, represented by GaNxAs1-x
The III-VN material lattice-matches with Si at about x = 0.2. In addition, by sequentially decreasing the nitrogen composition,
s can be lattice matched. In this case, the conventional AlGaAs-based semiconductor laser structure and manufacturing method for a flat substrate can be employed as it is.

The III-VN material can be an active layer that emits light having a wavelength of about 0.03 to about 1.3 μm. Therefore, in a known manufacturing method, a plurality of crystal planes can be formed on a single Si spherical surface on a plane equivalent to the (111) and / or (100) planes, and a plurality of semiconductor ring lasers independent of each other are integrated. Can be formed. In addition, by integrating the driving circuit and the signal processing circuit of the semiconductor ring laser in an empty space of a spherical surface, all the functions of the rotary gyro can be integrated by one three-dimensional semiconductor substrate, for example, a Si sphere. be able to.

It is theoretically possible to form a semiconductor ring laser on two kinds of surfaces equivalent to the (111) plane and the (100) plane on one three-dimensional, for example, spherical semiconductor substrate. It is possible, but in real life recipes, in general,
Since the crystal growth rate greatly differs depending on the crystal plane, it is difficult to grow the crystal all at once. Therefore, it is more preferable to form the semiconductor ring laser on a crystal equivalent, for example, an equivalent plane such as a (111) plane or a (100) plane.

Further, as a laser device, it is effective to provide a structure having a semiconductor ring laser on a silicon spherical surface and a gyro compass using the same.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a schematic diagram showing a first embodiment according to the present invention. In this embodiment, a spherical silicon ball (hereinafter, referred to as a Si sphere) is exemplified as a semiconductor substrate having a three-dimensional surface, and the three-dimensional surface is used to fabricate a semiconductor ring laser. A plane equivalent to the (111) plane is used for a plurality of crystal planes (planes) intersecting each other.

In the figure, 101 is a Si sphere having a diameter of about 1 mm, 102 is a crystal plane equivalent to the (111) plane, 103 and 104 are an optical device (semiconductor ring laser) formed on the crystal plane and An electronic device (such as a CMOS driver).

Reference numeral 105 denotes an electric wiring connecting these devices, and is arranged on the surface of the Si sphere 101. Reference numeral 107 denotes a printed circuit board for mounting the three-dimensional ring laser device of the present invention on a gyro compass.

Hereinafter, the manufacturing process will be described. S
Conventionally known techniques are used for the production of i-spheres. For example, as one of the techniques, granular polycrystalline Si is put into a pipe having an inner diameter of 2 mm and melted to form a substantially spherical single crystal. Thereafter, the surface of the single crystal is polished in the same manner as a ball bearing, and a true sphere having a diameter of 1 mm is formed to form a Si sphere.

Next, an oxidation or diffusion process is performed through a pipe. That is, pattern baking on the surface of the Si sphere (electronic device 104, electric wiring 105, etc.)
Can be realized by a method disclosed in, for example, JP-A-10-294254 or JP-A-11-54406. By the above steps, a Si ball IC for incorporating the semiconductor ring laser is completed (see FIG. 2).

Next, after the process of forming the Si ball IC is almost completed, the above-described optical device 102 is formed on the crystal plane 102. First, the entire sphere is covered with a nitride film 301 or the like, and the formed portion of the optical device 102 is ground, polished and polished to a flat surface (see FIG. 3). Where Si
The reason why the surface of the sphere 101 is covered with the nitride film is to protect the electronic device 104 and the like during fabrication of the optical device (crystal growth) and to use it as a mask for selective growth. Here, a triangular (11) having a side of about 50 μm is used.
1) A plane and an equivalent plane (eight in total) 302 are used.

If necessary, the entire surface of the Si sphere is again covered with a nitride film or the like.
A window may be opened only in the creation area 02. FIG. 4 is a cross-sectional view of the Si sphere (optical device forming region) after the step of forming the optical device forming region.

Next, the crystal growth of the optical device will be described. This is based on the “structure of an optical fusion device and a method of manufacturing the same” proposed by the present inventors (Japanese Patent Application No. 11-136).
No. 515). The point is that in order to grow an optical device on the (100) plane or the (111) plane, a selective growth mask made of a dielectric or the like is formed on a Si substrate. After forming a thin film made of a different first III-VN material, a second III-VN material having a longer lattice constant than the first III-VN material and a lattice constant shorter than the first III-VN material are formed. A multilayer thin film made of a third III-VN material is laminated while compensating for the strain, and during that time, the first III-V is grown laterally on the selective growth mask.
In a crystal plane having a lattice constant equal to that of the N material, the fourth
A film made of a III-VN material is grown, and a required optical device structure is laminated thereon.

As the first and fourth III-VN materials, G which is lattice-matched to GaAs (or InP) is used.
a InNAs (or GaInNAsP)
And, as the third III-VN material, GaNAs and AlNAs (or InNAs and InNP) are used, and AlGaAs / GaAs is formed on these crystals.
It is preferable that a multilayer structure composed of (or AlInNAsP / GaInNAsP) is used as a reflection mirror and a laser structure using a fifth III-VN material (or particularly, AlInNAsP) as a main active layer material is laminated.

As a specific example, a gas source MBE method or MOCVD method is used for forming the optical device shown in FIG. Here, GaNxAs1-x is laminated as a buffer layer 501 only in the selected region for producing the optical device. Then, the nitrogen composition X was gradually changed from 0.2 to 0 so as to lattice match with GaAs. Thereafter, the n-AlGaAs cladding layer 502 and the AlGaAs
s / GaAs is formed by an MQW (multiple quantum well) active layer 503;
p-AlGaAs is applied to the cladding layer 504 and further to p-Ga
As is sequentially stacked as a contact layer 505.

Next, as shown in FIG. 7, after a positive electrode 701 is formed, a waveguide mask pattern 702 of a semiconductor ring laser is formed by photolithography. In this embodiment, the resonator has a triangular shape (schematically shown in FIG. 6), and a vertical mirror is arranged at each corner.
The width of the optical waveguide is set to 4 μm so that fundamental transverse mode waveguide can be obtained. A deep UV negative resist was used as a mask material so that a high-definition pattern was obtained. Then, as shown in FIG. 8, etching was performed to a desired depth by dry etching. For the etching here, RIBE (Reacative Iron Beam Etchin
g) and ECR (Electron Cyclotron Resonance)
The power was set to 120 W and the extraction voltage was set to 350 V. Then, the etching depth was set to completely reach the buffer layer.

Subsequently, a negative electrode 703 was formed at a desired position, an unnecessary nitride film was removed, and wiring was performed with an IC electrode.
Here, if necessary, the ball IC and the mounting wiring board 107 are connected via the electrodes 106 and 108.
Connect (see FIG. 1). This connection method may be a method according to a normal flip-flop implementation.

Next, the operation principle of the semiconductor ring laser (the ring resonator 601 shown in FIG. 6) will be described. Reference numeral 602 denotes a corner mirror. The carrier supplied from the electronic device (electronic circuit) 104 is
Injected from the positive electrode 701 and the negative electrode 703 (see FIG. 8), they recombine in the active region, become photons, select a waveguide mode, and propagate. First, in the thickness direction, only the waveguide mode of a normal slab waveguide is selected. In the lateral direction, a lateral mode determined by the waveguide width is selected.

In FIG. 6, there is an axial mode for two oscillation modes, counterclockwise and counterclockwise. If the optical waveguides are completely symmetrical in the counterclockwise and counterclockwise directions, the two modes have the same oscillation threshold and wavelength. In this embodiment, since the light outlet is not provided, the light is
Since it is completely confined in the resonator, it can be operated with low current. If the optical waveguide has an asymmetric tapered region, the oscillation wavelength can be changed clockwise and counterclockwise. For example, Japanese Patent Application No. 12-00389
No. 5 has the description.

The situation in which the ball IC is used as a rotary gyro will be described below with reference to FIG. In the figure, reference numeral 901 denotes an optical device of the present invention formed on one crystal plane of a ball IC, 902 denotes a current source or amplifier, 903 denotes a resistor, and 904 denotes a current-voltage characteristic differentiating circuit. All of these electronic circuits, as described above,
These are integrated on the same Si sphere.

Here, by increasing the current, the resonator becomes
When the oscillation threshold is reached, the two modes oscillate almost simultaneously in the ring laser mode. In this embodiment, the oscillation cannot be confirmed by a normal photodetector because the semiconductor ring laser does not emit light. However, by monitoring the differential resistance, the oscillation threshold can be reduced. Can be monitored. That is, the diode characteristics are normal until oscillation, but after oscillation, since the carrier density in the active layer becomes constant, a kink is generated as the differential resistance, so that the oscillation can be easily determined.

Driving the semiconductor ring laser at a low current;
After oscillating, when the ball IC is rotated, clockwise,
In the counterclockwise mode, an optical path difference occurs, which appears as a beat signal in the voltage change. Normally, this beat frequency has a linear relationship with the number of revolutions of the ball IC, so that the number of revolutions can be quantified. When the semiconductor ring laser is driven at a low voltage, a beat signal appears as a change in current.

Further, in the present invention, as shown in FIG. 1, a plurality of semiconductor ring lasers are formed on a crystal plane equivalent to the (111) plane. For example, the crystal planes intersect at about 70 degrees between the (111) plane and the (-111) plane. That is, (111)
The rotation axis on the plane and the rotation axis on the (−111) plane
Since they intersect at an angle of 0 degrees, the two-axis rotating gyros are integrated in one ball IC.
You can know the rotation direction at the same time. In other words, by transferring the signal from each differentiating circuit 904 to another IC (signal processing circuit) on the same Si sphere, it is possible to know the rotational speed and the azimuth at the same time.

The crystal plane equivalent to the (111) plane is:
Semiconductor ring lasers having different structures may be integrated. In particular, since the rotation detection range of the Si sphere depends on the orbital length, it is possible to measure a wide range of rotational angles by integrating semiconductor ring lasers having different orbital lengths. Furthermore, it is of course possible to integrate semiconductor ring lasers having different oscillation wavelengths.

As described above, according to this embodiment, the following effects can be obtained. (1) Since a semiconductor ring laser and an electronic circuit for driving and signal processing the semiconductor ring laser can be simultaneously integrated on a Si sphere, miniaturization is easy.
Low cost. (2) One optical gyro with different rotation axes
Since it can be accumulated on two Si spheres, the rotation direction can be easily known as a gyro compass.

(Second Embodiment) FIG. 10 is a schematic diagram showing a second embodiment according to the present invention. In this embodiment, a spherical silicon ball (hereinafter, referred to as a Si sphere) is exemplified as a semiconductor substrate having a three-dimensional surface, and the three-dimensional surface is used to fabricate a semiconductor ring laser. A plane equivalent to the (100) plane is used for a plurality of crystal planes (planes) intersecting each other. Further, the active layer is made of AlGaAs / Ga as described above.
By changing from As MQW to GaInNAs / GaAs, the oscillation wavelength can be made longer. The shape of the resonator is rectangular. The production of the ball IC may be the same as that of the first embodiment.

Optical device (semiconductor ring laser)
Is a procedure for creating an optical device after the ball IC creation process on the Si sphere is almost completed, as described above. That is, the entire Si sphere is covered with the nitride film 301 or the like, and the optical device forming portion is ground, polished, and polished to a flat surface. Here, a (100) plane and planes equivalent thereto (equivalent planes (100), (010), (-100), (0-
10), a total of four planes) 302 are used.

As in the case of the first embodiment, if necessary, after covering the entire structure again with a nitride film or the like, a window may be opened only in the region where the optical device is to be formed.

For crystal growth, gas source MBE or MOCVD is used. Here, GaNxAs1-x is stacked as the buffer layer 501 only in the selected region. The lattice constant at this time may be appropriately selected according to the conditions of the cladding layer and the active layer. Here, In0.1G
After the nitrogen composition X is gradually changed from 0.2 to 0 so as to lattice-match with a0.9As, InGaAs is further laminated while the composition of In is gradually changed.

Thereafter, the cladding layer 501 of n-InAlGaAs, GaInNAs / InAlGaAs MQW
(Multiple quantum well) Active layer (emission wavelength: 1.3 μm) 50
2. A cladding layer 503 of p-InAlGaAs and a contact layer 504 of p-InGaAs are sequentially formed.
Laminate. Subsequent steps are the same as those in the first embodiment, and the operation principle and the method of use are almost the same.

In this embodiment, the following effects can be obtained. (1) Since the oscillation wavelength is 1.3 μm, it is a transparent wavelength with respect to the band gap of Si, and is not absorbed by Si spheres. It is effective for (2) The oscillation wavelength is 1.3 μm (band gap: 0.9
5 eV), the driving voltage can be reduced, and even a low-voltage driving CMOS (for example, 1.5 V) can be driven sufficiently and can operate with low power consumption. (3) Since the rotation axis is completely shifted by 90 degrees, the rotation direction can be easily known.

In both of the above embodiments, the semiconductor substrate having a three-dimensional surface is exemplified by a spherical one. In the case of a polyhedron such as icosahedron, or a similar form, a semiconductor ring laser is formed for each of a plurality of required crystal planes crossing each other, and electronic circuits such as a driving circuit and a signal processing circuit thereof are formed. Of course, the circuit may be formed on the semiconductor substrate.

[0045]

According to the present invention, as described in detail above, a semiconductor ring laser is formed on a three-dimensional semiconductor substrate, for example, a Si sphere, with respect to a plurality of crystal planes crossing each other. Since electronic circuits for driving and signal processing of the laser can be integrated at the same time, miniaturization is easy and low cost can be realized. Further, by using this three-dimensional ring laser device, optical gyros having different rotation axes can be integrated on one substrate, so that the rotation direction can be easily known.

Further, if necessary, by selecting the transparent wavelength of Si (for example, 1.3 μm) as the oscillation wavelength, the buffer layer and the cladding layer can be made thin because they are not absorbed by the Si semiconductor substrate, for example, the Si sphere. , Low-voltage operation becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a ball IC on a Si sphere in the same manufacturing process.

FIG. 3 is a schematic plan view showing a crystal plane.

FIG. 4 is also a schematic cross-sectional view of a crystal plane.

FIG. 5 is also a schematic diagram showing a process of forming a resonator (semiconductor ring laser) on a crystal plane.

FIG. 6 is a schematic plan view showing a process of manufacturing the resonator.

FIG. 7 is a schematic cross-sectional view showing a process of manufacturing the resonator.

FIG. 8 is also a schematic cross-sectional view when the fabrication of the resonator is completed.

FIG. 9 is a block diagram of the resonator and its driving and signal processing circuits.

FIG. 10 is a schematic diagram illustrating a second embodiment of the present invention.

FIG. 11 is a schematic view of a resonator on a conventional flat substrate.

[Explanation of symbols]

 101 Si sphere 102 Crystal plane 103 Semiconductor ring laser 103a, 103b, 103c Ring laser 104 Electronic device (electronic circuit) 105 Electric wiring 106 Mounting electrode 107 Printed circuit board 108 Wiring electrode 301 Nitride film (mask) 501 Buffer layer 502 Cladding layer 503 Active layer 505 Contact layer 601 Ring resonator 602 Corner mirror 701 Electrode (positive electrode) 702 Mask 703 Negative electrode 901 Ring laser 902 Amplifier 903 Resistance 904 Voltage differentiation circuit

Claims (8)

[Claims] 1. A semiconductor ring laser is formed on each of a plurality of intersecting crystal planes (planes) formed on a semiconductor substrate having a three-dimensional surface.
An electronic circuit for driving or processing a signal of the semiconductor ring laser is integrated and formed on the semiconductor substrate. 2. The semiconductor substrate according to claim 1, wherein the semiconductor substrate is made of a sphere, a polyhedron, or a Si similar thereto, and the crystal plane is formed on a plane equivalent to the (111) plane. The three-dimensional ring laser device according to claim 1, wherein at least one semiconductor ring laser is formed on the surface. 3. The semiconductor substrate is formed of a sphere, a polyhedron, or a Si similar thereto, and the crystal plane is formed on a plane equivalent to a (100) plane thereof. The three-dimensional ring laser device according to claim 1, wherein at least one semiconductor ring laser is formed on the surface. 4. The semiconductor substrate is made of a sphere, a polyhedron, or a Si similar thereto, and the crystal plane is formed on a plane equivalent to the (111) plane and the (100) plane, respectively. And on the crystal face,
The three-dimensional ring laser device according to claim 1, wherein at least one semiconductor ring laser is formed. 5. The semiconductor ring laser includes, as a part of its constituent material, GaNAs, GaInNAs, AlNA
The three-dimensional ring laser device according to claim 1, wherein a III-VN semiconductor material such as s or GaInNAsP is used. 6. A gyro configured by the three-dimensional ring laser device according to claim 1, wherein the gyro is configured to detect a three-dimensional azimuth by a tilt between semiconductor ring lasers formed on a plurality of crystal planes. ·compass. 7. A laser device having a semiconductor ring laser on a silicon spherical surface. 8. A gyro compass using the laser device according to claim 7.