JPS61156205A - Photoelectric composite circuit - Google Patents

Abstract

PURPOSE:To suppress light returning to a light emitting source, by providing plural various element on a substrate and means which give light transmitting characteristics unreversible in the transmitting direction between the elements on the substrate and to the light emitting surfaces of elements having laser light emitting functions among the elements of other substrates. CONSTITUTION:Parallel light transmitting signals are converted into parallel electrical signals by means of a photodetector element array 3 and the parallel electric signals are subjected to processes, such as intersignal operation, switching of signal route, etc., at a electronic circuit chip 4. The processed electric signals are inputted in a semiconductor laser array 5 and, after they are converted into optical signals again, sent to an output optical fiber 8. In order to stably operate the individual oscillation of the semiconductor laser array 5 without noises, it is necessary to suppress reflecting lights produced at the connecting point of an optical waveguide 9 which leads the light emitted by the laser array 5 to the optical fiber 8 and the optical fiber 8 and the returning light by reflection from the other end of the optical fiber 8. Since an optical isolator 6 provided at the light outgoing end face of the laser array 5 rotates the polarized light of the above-mentioned reflected returning light by 90 deg., nonoise is induced to the laser array 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an opto-electrical composite circuit in which a large number of optical elements, electronic elements and opto-electrical composite elements are arranged on a single substrate.

(Prior art and its problems) As has become clear with the development of optical communication technology, optical signal transmission is capable of extremely wide-band and high-speed signal transmission, and the thin core of the optical waveguide makes optical signal transmission possible. It has many features such as extremely low crosstalk between lines even when wires are arranged in a high density, waveguides can cross because the light travels in a straight line, and high-density wiring can be expected. ing. By applying this feature to wiring in electrical circuits, we can create multi-channel photodetectors,
An opto-electrical composite device that integrates electronic circuits, light-emitting devices, etc., an optical memory that stores the signal light emitted from the opto-electrical composite device, and the signal light that enters the device as it is, or an optical switch that controls the optical path. Optical elements such as optical gates, electronic elements for electrically controlling these optical elements and the opto-electrical composite element, etc. are arranged on a single substrate, and optical wiring having the above-mentioned characteristics is interposed between these elements. By connecting them together, it is possible to form an optical/electrical composite circuit with high-speed, high-density processing and calculation performance.

Another concept is to have means for receiving signal light on one side of the substrate, and means for emitting light on the opposite side of the substrate, and these form an optical feedback circuit via the substrate. The bistable device with an open planar configuration can have an optical logic operation function by using multiple optical inputs, so these bistable devices with an open planar structure can be arranged in a two-dimensional array on a single board to create an optical logic operation board. A plurality of logic operation boards are connected vertically so that their surfaces overlap, and the output light of any bistable device element on any one board is transmitted between the boards to any bistable device element on the other board. By inserting an optical connection board that has the function of connecting to the input light of a device element, two-dimensional optical signals such as image information can be transmitted in an electrically current one-dimensional column array or temporal series. Two-dimensional optical calculation processing is being considered in which light is processed in parallel at high speed without converting it into a signal and performing sequential calculations and processing.

The light-emitting elements included in optical memory devices, opto-electrical composite devices, etc., are not light-emitting diodes due to their high operating speed.
A semiconductor laser is used.

As is well known, in a semiconductor laser, when a small amount of reflected light from a reflecting surface of a semiconductor laser oscillates to the outside enters the semiconductor laser again, noise induced by the returned light occurs in the oscillated light. This noise hinders high-speed signal transmission and also becomes an obstacle in constructing the opto-electrical composite circuit. In optical transmitting modules in terminal equipment for optical communications, the light possessed by magneto-optic materials is used to block light returning from the light input end of the optical fiber into which the emitted light from the semiconductor laser is injected and the connection end with the connector etc. An optical isolator that uses non-reciprocity of photometric rotation is used.

That is, when a strong magnetic field of about 1000 Gauss is applied to a yttrium iron garnet crystal in the direction of light transmission, the polarized light transmitted through the crystal is rotated due to the Faraday effect. If the length of the crystal is set so that the polarized light undergoes 450 rotations, the reflected light undergoes 900 polarization rotations in a round trip, and the polarization is perpendicular to that of the light emitted from the semiconductor laser. Therefore, the intensity of noise generated even if the light enters the semiconductor laser again is small.

The optical isolator described above is extremely effective as an element for suppressing the return light of a semiconductor laser, but it requires a permanent magnet that generates a strong magnetic field of about 10" Gauss, and the shape is 8IrI11 in diameter and 3 to 30cm in length. It is large at 5ff.Also, the optimum light transmission length of the crystal is long at nearly 2.5jff for light with a wavelength of 1.3μm.For this reason, the laser beam is collimated using a lens, transmitted through the crystal, and then used again by the lens. It is necessary to have a configuration in which the light is focused by the optical fiber, which is an optical waveguide, and then input into an optical fiber, which is an optical waveguide.Since such a configuration is large and complicated, it is difficult to install it on the optical printed circuit board mentioned above. It is not suitable for arrayed light sources.

As described above, an opto-electrical composite circuit having a light emitting source on a substrate and having means for suppressing light returning to the light emitting source has not yet been invented.

- (Objective of the Invention) An object of the present invention is to have a means for suppressing the return light to the light emitting sources arranged in a dense manner, which is simply added to the light emitting sources arranged densely, without using the above structure. The object of the present invention is to provide an opto-electrical composite circuit.

(Structure of the Invention) A plurality of optical elements, electric elements, and opto-electrical composite elements are arranged on one substrate, and connections between the elements and another substrate having the same configuration as the substrate are electrically and optically connected. High performance and stability can be achieved by providing a means for imparting irreversible light transmission characteristics in the transmission direction to the light emitting surface of the element having a laser emission function among the elements connected and disposed on the substrate. A photoelectric composite circuit is obtained.

(Function/principle of invention) FIG. 3 is a diagram explaining the principle operation of the present invention.

1 is a striped semiconductor laser chip that forms a laser resonator by cleavage, which is commonly used;
2 is an active region, and the light emitting surface of the semiconductor laser chip includes:
S10. A rare earth iron garnet film 4 is formed with an optical buffer layer 3 interposed therebetween. The thickness of the optical buffer layer 3 is as follows when the garnet film 4 is provided on the cleavage plane of the semiconductor laser chip.
In order to construct a laser resonator, a thickness of, for example, about wavelength b is provided so as to obtain the necessary reflectance. Light oscillated by the semiconductor laser chip and having an electric field component mostly vibrating parallel to the active layer passes through the buffer layer 3 and the rare earth iron garnet film 4 . At this time, the polarization direction is rotated by 450 degrees due to the Faraday effect of the garnet film 4. When the reflected light from the reflective surface existing outside the semiconductor laser passes through the garnet film 4 again, it undergoes a further 45' polarization rotation, and since the direction of polarization is perpendicular to the oscillation light of the semiconductor laser, the light is reflected into the active region 2. Even if it is incident, it does not induce noise in the oscillated light. If an iron garnet film with a high concentration of bismuth atoms is used as the garnet film, the thickness may be about 15 μm for a 0.8 μm laser, and physical processes such as sputtering and molecular beam epitaxy can be used. It can be provided by a film method (PVD method). Furthermore, in a highly concentrated bismuth iron garnet film, the direction of the force perpendicular to the film surface can be set as the axis of easy magnetization, and once a magnetic field 5 of about 200 Gauss is applied after the film is formed, it becomes a single magnetic domain, and even if this magnetic field is removed, Since the magnetic domain structure is maintained, the large magnet for applying the magnetic field described above is not required. Garnet) 9
The composition R, FasO* (R is a rare earth atom), where the oxygen atom is replaced with a sulfur atom, for example, R@F@%S”
With the composition of 1404-6, the Faraday rotation ability further increases, so the film thickness required to rotate polarized light by 450 becomes thinner. Therefore, if an optical waveguide is provided in the immediate vicinity of the surface of the garnet film 4, the oscillation light of the semiconductor laser can be efficiently excited into the optical waveguide without using a coupling lens or the like.

In this way, since components such as magnets and lenses are not required, coupling between the array light source and the array waveguide can be easily realized.

(Example 1) FIG. 1 is an example of an optical printed board constructed using the principle operation of the present invention described above. 1 is a silicon substrate for mounting electronic circuit chips, light emitting/receiving elements, optical switches, etc., 2
An input optical fiber 3 to which parallel optical signals are transmitted is a photodetector array that receives the input parallel optical signals through an optical waveguide 9 provided on a silicon substrate 1, and 4 is an electric signal that is photoelectrically converted by the photodetector array 3. An electronic circuit chip that performs arithmetic processing on signals; 5 is a semiconductor laser array that converts the arithmetic output signal of the electronic circuit chip 4 into light; 6 is a semiconductor laser 5;
An optical isolator 8 provided on the end face of the semiconductor laser array 5 is an output optical fiber for outputting and transmitting parallel output optical signals output from the semiconductor laser array 5. In addition, 10.11 is an input optical fiber and an output optical fiber for transmitting high-speed time-multiplexed optical signals, and 12 is for switching the time-multiplexed optical signals transmitted through the input optical fibers to four optical memory arrays every time slot. 13 is an optical switch that multiplexes the optical output signals of the four optical memory arrays into one time-multiplexed signal and sends it to the output optical fiber, and 15 is an electronic circuit chip that controls the optical switch. 16 is an optical isolator provided on the light emitting end surface of the optical memory array.

e- The parallel optical transmission signal is converted into a parallel electrical signal by the photodetector array 3, and this parallel electrical signal is processed by the electronic circuit chip 4, such as calculations between the signals or signal path switching, and then processed by the semiconductor laser array 5. is applied to the optical fiber 8, is converted into an optical signal again, and is sent to the output optical fiber 8. In order for each oscillation operation of the semiconductor laser array 5 to operate smoothly and stably, the reflected light generated at the connection point between the optical waveguide 9 that guides the emitted light of the semiconductor laser array 5 to the output optical fiber 8 and the output optical fiber 8 is required. It is also necessary to suppress reflected return light from the other end of the output optical fiber 8. Semiconductor laser array 5
As described above, the optical isolator 6 provided on the light emitting end face of
Since the rotation is zero, no noise is induced in the semiconductor laser array 5.

Further, the opto-electrical composite circuit formed in the lower part of the silicon substrate 1 in FIG. 1 operates as follows.

The high speed time multiplexed optical signals are coupled into the opto-electrical composite circuit by 100 input optical fibers. The input optical signal is route-switched for each signal time slot by the optical switch 12 under the control of the electronic circuit 15 that controls the optical switch 12, and is written into different optical memories of the optical memory array 14. The light emitted from the optical memory array 14 is reassembled into a time-sequenced signal order by the optical switch 13, which operates under the control of the electronic circuit 16 that controls the optical switch 13, and is sent out again to the output fiber 11 as a time-multiplexed optical signal. Ru. This entire optical circuit functions as an optical time switch. In this circuit system as well, the light-emitting surface of the optical memory array 14, which is a light-emitting element, is equipped with the optical isolator 17 as described in the above-mentioned operation principle.

This prevents the light reflected from the connection part between the optical memory array 14 and the optical waveguide, the joint part between the optical waveguide and the optical switch 13, the optical fiber entrance surface, etc., from entering the optical memory again, thereby reducing noise in the optical memory array 14. Stable operation without any problems is ensured.

Such a photoelectric composite circuit can be manufactured as follows. Necessary optical waveguides and electrical lines are formed in advance on a well-polished silicon substrate using quartz, a light-transparent resin-metal thin film, etc., to form photodetector arrays, electronic circuit chips, semiconductor laser arrays, optical switches, etc. is installed on a silicon substrate using a technique such as solder fusion. Thereafter, necessary electrical connections between each chip are made using wire bonding or the like. Garnet films with excellent Faraday rotation performance are applied to the light-emitting surfaces of chips with light-emitting functions, such as semiconductor laser arrays and optical memory arrays, using the PVD method (physical paper deposition method) as described in the section on principle of operation. , these chips are formed before being fused onto a silicon substrate. When the entire optical printed board has been assembled, a strong permanent magnet is brought close to the chip having a light emitting function, or the optical printed board is inserted into an electromagnetic coil to align the direction of the spontaneous magnetization of the optical isolator. Of course, the permanent magnet may remain fixed near the chip of the light emitting device.

(Embodiment 2) Figure 2 is a configuration diagram of another embodiment of the present invention.
, 102 is an electronic circuit chip 103 and a surface emitting laser 104
．． The light receiving element 105 is mounted by fusion bonding or the like, and is a silicon substrate forming a printed board substrate on which electrical wiring is provided between the circuit chips and between the electronic circuit chip and the surface emitting laser and the light receiving element. The signals processed by the electronic circuit mounted on the silicon substrate 101 are supplied not only to the electrical connection 106 between the printed boards but also to the surface emitting laser array 104, and then transmitted via light waves to the silicon substrate 102, which is another printed board. The light is transmitted through the silicon substrate to a light receiving element 105 provided in the silicon substrate.

By using this method of connection between surfaces using light, electrical signals are propagated from one end of the board to the other, and electrical connections 10
6 to another board, and the signal is transmitted between the boards at high speed without undergoing a signal delay such that the signal is transmitted further to the end of the board.

In this case as well, the emitted light to the surface emitting laser 104 is reflected from the surface of the silicon substrate 1020 and enters back again, causing the aforementioned instability of oscillation and increase in laser oscillation noise.

For this reason, in this embodiment, for each laser of the surface emitting laser array, a garnet film 203 is provided on the light emitting surface of the surface emitting laser chip 2010 with a buffer layer 202 interposed therebetween, as shown in FIG.

It is empirically known that the oscillation light of a surface emitting laser is linearly polarized light. Therefore, similar to the striped semiconductor laser in which the resonator is formed by ordinary cleavage shown in FIG. 3, this structure can suppress the generation of noise induced by the returning light.

In FIG. 2, the light emitting surface of the surface emitting laser 104 is shown to be in direct contact with the air, but the surface emitting laser 104 may be emitted through the substrate. In other words, in FIG. The light emitting surface of the surface emitting laser is in contact with the silicon substrate, and the light is transmitted through this to emit all of the light. A case has been described in which the electrical circuit is provided by solder welding on a silicon substrate on which no pattern of an electrical circuit is formed. In recent years, new stacking process techniques have been developed to realize two-layer LSIs. In other words, metal is opened only at the connection points of the single-layer chip, the rest is covered with a dielectric material such as polyimide, and the flattened batten forming surfaces are stacked and thermocompressed, and the two are connected via vertical metal wiring at the connection points. It realizes a layered circuit.

Using this technology, it is possible to attach each element to a microcontroller board on which a circuit pattern is formed, and then attach a chip formed in a composite two-layer structure using the above method to a silicon substrate, increasing the packaging density and wiring. Speed-up can be achieved by reducing the length.

(Effect of the invention) As described above, according to the present invention, a large number of optical elements.

It is possible to realize an opto-electrical composite circuit in which an electric element and an opto-electrical composite element are mounted on a single substrate, and the optical connection function between the elements operates stably.

[Brief explanation of drawings]

1 and 2 are diagrams showing embodiments of the present invention, 1...
Silicon substrate, 3... Light receiving element array, 4... Electronic circuit chip, 5... Semiconductor laser array, 12°13
... Optical switch, 14 ... Optical memory array, 103
-11 is a sub-circuit chip, 104... surface-emitting laser array, 105-... light receiving element array, FIGS. 3 and 4 are diagrams showing the structure of a light emitting element equipped with an optical isolator. , Yaso Rutoben! shi varus shoulder 1・゛4, force - net single side

Claims (2)

[Claims] (1) A plurality of optical elements, electric elements, and opto-electrical composite elements are arranged on one substrate, and the elements and other substrates having the same configuration as the substrate are electrically and optically connected. , and further comprising means for imparting irreversible light transmission characteristics in the transmission direction to the light emitting surface of the element having a laser emission function among the elements disposed on the substrate. circuit. (2) Optical connections between substrates on which multiple optical elements, electric elements, and opto-electrical composite elements are arranged can be made by connecting the light waves emitted from one substrate to the other substrate and connecting to the other substrate. 2. The opto-electrical composite circuit according to item 1 above, wherein the opto-electrical composite circuit is constructed by transmitting either one or both of them.