JPH04286375A - Optical integrated device - Google Patents

Abstract

PURPOSE:To provide an optical integrated device which is adapted to the transmission of data of large capacity through a short distance, easily aligned, high in operation speed, hardly affected by electrical noises, and high reliability. CONSTITUTION:Light emitting devices l and photodetective devices 2 including at least light emitting device 1 are arranged on a first primary surface out of a first and a second primary surface of a semiconductor substrate 3 opposed to each other, and light reflecting planes 4 processed into slopes are provided to the second primary surface.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical integrated device used for short-distance, large-capacity data transmission.

0002

[Prior Art] Research is progressing on methods for short-distance, large-capacity data transmission using light as a medium due to its advantages of power saving and noise resistance. There is information transmission. As shown in FIG. 4, the conventional method uses a glass flat plate 12, and arranges a microcavity laser 13 and a light receiving element 14 on one side of the plate, and a plurality of diffractive reflecting mirrors 15 on the other side. (Optical Computing Conference, Kobe, 1990, 10B)
4). In FIG. 4, 16 is a spacer, 17 is an optical component forming substrate, and 18 is an electronic circuit integrated substrate. Here, the light from the microcavity laser 13 is transmitted to the glass flat plate 1.
2, and enters the diffractive reflector 15 on the opposite side,
The reflected light from this reflecting mirror propagates through the glass flat plate 12 again and is detected by the light receiving element 14 arranged on the same plane as the microcavity laser 13 . In this way, optical connections between a plurality of optical devices can be realized via the glass flat plate 12. In order to achieve highly efficient optical coupling, it is essential to align multiple optical components, which not only requires advanced alignment technology but also requires a hybrid configuration consisting of multiple components. In this case, assembly and fixation are essential, and there is a concern that reliability may deteriorate due to aging of the bonded parts. In addition, the spacing between devices that can be coupled in the lateral direction is determined by the spread of the beams of the multiple diffractive reflectors used as relay elements. Even if the reflected light is spontaneously emitted light with a large beam spread, there is a drawback that the number of relay elements increases. Furthermore, the poor directivity of spontaneously emitted light makes it difficult to perform precise optical coupling between specific devices.

0003

[Problems to be Solved by the Invention] As described above, in conventional optical integrated devices, it is difficult to perform alignment and high-precision optical connections between specific devices, and as the distance between devices increases, the number of relay optical devices increases. An object of the present invention is to solve these problems and realize an optical integrated device with excellent high speed and high reliability.

0004

[Means for Solving the Problems] According to the present invention, a plurality of optical devices including a surface light emitting device are formed on the side of a semiconductor laminate, and a semiconductor multilayer film with high reflectivity is disposed on the surface light emitting device. This improves the directivity of the output light. The light with a small beam spread emitted to the semiconductor substrate side is reflected by a reflection surface tilted at 45 degrees from the substrate surface provided on the substrate side, changes its course from the vertical direction to the horizontal direction, and propagates to the central axis of the light receiving device. At that point, the light is reflected again by another reflective surface tilted at 45 degrees and is perpendicularly incident on the light receiving element.

[0005]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of an optical integrated device according to a first embodiment of the present invention, in which 1 is a surface light emitting device, 2 is a light receiving element, 3 is a GaAs substrate, 4 is a 45-degree reflective surface, and 5 6 and 7 indicate an electrode, 6 and 7 indicate an LSI circuit chip, and 8 indicates an electrode. This embodiment is an optical integrated device for the purpose of data transmission between two LSI circuit chips 6 and 7, and shows a case where light emitting and receiving devices are coupled one-to-one. The output terminal of the LSI circuit chip 6 is connected to the anode terminal of the surface light emitting device 1, and the input terminal of the LSI circuit chip 7 is connected to the light receiving element 2.
The structure is such that the output terminals of the two are connected to each other. A microcavity laser was used as the surface light emitting device 1, and a PIN photodiode was used as the light receiving element 2. A microcavity laser is a laser that uses an InGaAs superlattice as an active layer and has a cavity length equal to the wavelength λ. The oscillation wavelength is 0.98 μm, and the laser light is hardly absorbed by the GaAs substrate 3. The board thickness is 30
0 μm, the distance between the laser and photodiode is 100 μm.
It is μm. The reflector on the substrate side of the micro-cavity laser 1 is a reflector made of a semiconductor multilayer film made by laminating multiple λ/4 thick semiconductor layers with different refractive indexes, and is made of AlAs/G.
It was fabricated by depositing 20 layers of aAs. Reflectance is approximately 95%
Met. The reflective surface on the front side of the semiconductor stack is made of AlAs
/GaAs is deposited in 28 layers, and the reflectance is approximately 99%.
Met. The structure had a diameter of 20 μm, and the threshold current was 1 mA. The optical output measured through the board when 3 mA current is applied is 0.8 mW, and the full width at half maximum of the far field pattern at this time is:
It was about 2 degrees. A crystal for producing a PIN diode was produced by growing a crystal for laser production, selectively etching it until it reached the substrate, and then growing the crystal a second time. By making full use of heteroepitaxial growth technology, a PIN type photodiode with an InGaAs absorption layer was formed. The diameter of the light receiving area is 30μm,
The capacitance was 0.5 pF. The quantum efficiency for light of 0.98 μm was 70%. 45 onto the board surface
The slope processing was performed by RIE dry etching. By tilting the rotation stage and performing etching twice, two slopes (45-degree reflective surfaces 4) having complementary angles to each other were formed. The etching depth was 10 μm. After forming the reflective surface, the electrode 5 on the substrate side is made of AuGeNi/A
It was formed by vapor depositing u on the entire surface. The cutoff frequency of a small signal down 3 dB was 1.5 GHz in the frequency characteristics measured with a PIN diode after the optical output from the microcavity laser was input and reflected twice on the reflective surface on the substrate side. In data transmission experiments using LSI circuit chips, we were able to confirm a speed of 400 Mbit/s. FIG. 2 is a block diagram of a second embodiment of the present invention, showing the connection state between four LSI circuit chips 9 (A to D). In this embodiment, two optical integrated devices 10 of the present invention are used, and FIG.
The same reference numeral indicates the same thing. Data is transmitted from A and C to B, from B to D, and from D to A. FIG. 3 is a diagram showing a third embodiment of the present invention, and is a perspective view of an optical integration device for optical coupling that branches into 1:4. Polygonal pyramidal reflective surface 1 located under the surface light emitting device 1
1 has a four-sided pyramidal shape with side surfaces having slopes inclined at ±45 degrees from the semiconductor substrate surface. Surface light emitting device 1
The emitted light is divided into four equal parts by a four-sided pyramid having an apex on the central axis, is reflected from each side, propagates in four directions, and is reflected again at the reflective surface 4 below each light-receiving element 2. , the light is received with high efficiency by being incident perpendicularly to the light receiving surface. In this way, the number of elements that can be coupled can basically be increased in proportion to the number of side surfaces of the reflective surface. In the above embodiment, the surface light emitting device is a microcavity laser, but similar effects and actions can be expected with an LED. Further, there is no problem at all even when the microcavity laser is operated in the LED mode. In the above embodiment, a monolithic over-integration case was shown for forming the photodetector, but since the photodetector has a relatively large light-receiving area, a hybrid integration format in which chips fabricated using other substrates are fused is used. is also quite practical. In the above example, the emission wavelength was 0.98 μm.
However, the present invention is not related to the wavelength of light in principle, and as long as the light is transparent to the semiconductor substrate, the light output level of the light emitting device can be lowered, which is advantageous in terms of power saving. It's advantageous. There is no problem even when using a long wavelength band crystal, a heteroepitaxial crystal grown on a silicon substrate, or the like.

As explained above, the optical integrated device of the present invention realizes a transmission path between spatially separated elements on the same plane using a three-dimensional optical path passing through the substrate. By realizing optical transmission, it is possible to realize a device that is easy to align, has excellent high speed, is less affected by electrical noise, and is highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an optical integrated device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the structure of an optical integrated device according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing the structure of an optical integrated device according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the structure of a conventional optical integrated device.

[Explanation of symbols]

1　Surface light emitting device 2 Photo receiving element 3 GaAs substrate 4 45 degree reflective surface 5 Electrode 6 LSI circuit chip 7 LSI circuit chip 8 Electrode 9 LSI circuit chip 10 Optical integrated device 11 Polygonal pyramidal reflective surface 12 Glass flat plate 13 Micro cavity laser 14 Photo receiving element 15 Diffractive reflector 16 Spacer 17 Optical component forming board 18 Electronic circuit integrated board

Claims (5)

[Claims] [Claim 1] A first and a second facing each other on a semiconductor substrate.
A plurality of light emitting/receiving devices including at least one surface light emitting device are arranged on the first main surface of the main surface, and a plurality of sloped light reflecting surfaces are arranged on the second main surface. An optical integrated device characterized in that: 2. A semiconductor integrated circuit chip electrically coupled to a plurality of light emitting devices including the surface light emitting device is disposed on the first main surface. optical integrated device. 3. The optical integrated device according to claim 1, wherein the reflective surface is constituted by a slope inclined at 45 degrees with respect to the second main surface of the semiconductor substrate. . 4. The reflective surface is located on the central axis of the surface light emitting device, and has a polygonal pyramidal shape composed of slopes inclined at ±45 degrees from the semiconductor substrate surface. 3. The optical integrated device according to claim 1 or claim 2. 5. The optical integrated device according to claim 1, wherein the front light emitting device includes a reflective surface made of a semiconductor multilayer film.