JPH05303123A - Parallel optical data transmitter - Google Patents

Abstract

PURPOSE:To obtain the parallel optical data transmitter which transmits parallel optical data by an optical waveguide circuit. CONSTITUTION:This parallel optical data transmitter has a phase conjugate mirror 8b which can write two-dimensional data of an LED array 7, a laser beam source 4 which drives this phase conjugate mirror, a reference beam waveguide circuit 31 which transmits part of the laser beams emitted by the laser beam source as reference beam to the phase conjugate mirror, a transmitted light waveguide circuit 32 which transmits the rest of the laser beams emitted by the laser beam source as transmitted beams and retransmits a conjugate wave generated by the phase conjugate mirror to carry the two-dimensional data to the side of the laser beam source, read-side optical systems 9c and 10b which image the conjugate wave on a read side, and a photodiode array 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel optical data transmission device capable of transmitting two-dimensional data in parallel by an optical waveguide circuit.

[0002]

2. Description of the Related Art In recent years, with the progress of LSI integration,
Since the number of bits per word of data handled inside the LSI is increasing, the number of pins for exchanging signals with the LSI chip is increasing. Therefore, as for the size of the LSI, the pin foot is required to have a larger area than the chip itself.

In order to solve this problem, an attempt has been made to integrate an optical modulator and a photodetector in an LSI chip and use light for wiring within the LSI chip or between the LSI chips. For example, the literature (JWGoodman, Frederick J. Le
onberger, Sun-Yuan Kung, andRavindra A, Arthale, P
roceedings of the IEEE magazine, Vol. 72, No. 7, 850-
866, 1984) it has been proposed to use holograms as a means of optical addressing. Figure 1 shows the configuration reported in that document. In the figure, 101 is a hologram, 102 is an LSI chip, 103 is a modulator chip, 1
Reference numerals 04A to 104D are optical modulators, and 105A to 105D are photodetectors (photodiodes). Further, the chips 103 and 104 include four blocks A, B, C,
It is divided into D. The laser light source of the reading light is omitted. The outline of the operation of this device is as follows. Logical processing and storage are performed for each block, but communication with other blocks is performed by optical signals. Focusing on the block A, the read light is incident on the optical modulator 104A of the block A. The light from the light source is a fixed light, and the light modulator 10
It is modulated into pulsed light at 4A. Readout light is optical modulator 1
The light is reflected by 04A and enters the hologram 101. The wiring pattern is already stored on the hologram 101,
The light from the light modulator 104A is reflected by the hologram 101 and enters the photodetector 105D on the block D.
This optical signal is photoelectrically converted again by the detector 105D and processed in the block D. On the other hand, the data from the optical modulator 104C of the block C is transmitted to the block A and photoelectrically converted by the photodetector 105A. Such an optical wiring system can be applied not only to wiring within a chip but also to wiring between chips or between boards.

[0004]

However, as can be seen from FIG. 1, in the conventional configuration, the hologram, the reading light source, the LSI chip, and the modulator chip are arranged at a considerable distance from each other. There is a problem in that it is extremely difficult to integrate the LSI placed on the other side with other holograms and the reading light source, and thus it is impossible to reduce the size.

Therefore, it is an object of the present invention to provide a parallel optical data transmission device capable of transmitting parallel data by an optical waveguide circuit and capable of being miniaturized.

[0006]

In order to achieve the above object, the present invention provides a phase conjugate mirror capable of writing two-dimensional data, a laser light source for driving the phase conjugate mirror, and a laser light source for emitting light. A reference light waveguide circuit for transmitting and irradiating a laser light acting as reference light obtained by separating a part of the laser light to the phase conjugate mirror, and the remaining transmission of the laser light emitted from the laser light source. A transmission light waveguide for transmitting and irradiating a laser beam acting as light to the phase conjugate mirror and irradiating the conjugate wave having two-dimensional data generated by the phase conjugate mirror again to the laser light source side. It is characterized by comprising a circuit and a reading side optical system for forming an image of the conjugate wave on the reading side.

As one form of the present invention, the phase conjugate mirror is an optical writing type spatial light modulator using a photoconductive layer and a liquid crystal.

As another aspect of the present invention, the phase conjugate mirror is a degenerate four-wave mixing optical system made of a photorefractive crystal, a photochromic material, or an optical nonlinear material having third-order nonlinearity.

[0009]

According to the present invention, with the above configuration, two-dimensional data can be transmitted by only two optical waveguide circuits or optical fibers. Therefore, according to the present invention, 100 to 10,000 bits can be transmitted in 1 bit time, as compared with the case where data is transmitted by 1 bit in time series by the conventional optical waveguide. In other words, according to the present invention, since only two optical waveguides can be used for transmission in a device in which a large number of optical waveguides provide parallelism in order to increase the transmission rate, the configuration of the device is significantly simplified. be able to. Furthermore, according to the present invention, image signals of televisions or the like, which have been sent in time series, can be transmitted at a high rate, so that ultra-high-speed image transmission not limited by the frame rate becomes possible.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Prior to the description of a specific embodiment, the principle of parallel data transmission in the present invention will be described with reference to FIG. In the figure, 8a is a phase conjugate mirror capable of writing two-dimensional data, 9a and 9b are beam splitters, 12a and 12b are lenses, 21 is a halogen lamp as a light source for irradiating two-dimensional data, and 22 is two-dimensional data. The laser light sources of the reference light E1 and the transmitted light E3 are omitted, but both are coherent light emitted from one laser light source.

First, the mechanism by which the phase conjugate wave is generated in the right portion from the phase conjugate mirror 8a when the halogen lamp 21 is not illuminated will be described. This FIG. 2 corresponds to two-wave mixing.

The reference light E1 is collimated into parallel light and is incident perpendicularly to the surface of the phase conjugate mirror 8a. The transmitted light E3 is also collimated into parallel light in advance, but after passing through the beam splitter 9b, the parallel light is incident on an aberrator (an object having a phase distribution but no absorption, for example, a molten glass plate or frosted glass) 23. Not be.
This spread light E3 does not return following the same locus even if it is incident on a normal mirror, but if it is incident on the phase conjugate mirror 8a, the conjugate wave E4 thereof travels toward the aberrator 23 again regardless of the presence of the aberrator 23. Follow the same trajectory in the opposite direction,
Further, it returns to the light source (not shown) of the transmitted light E3.

As the phase conjugate mirror 8a of FIG. 2, for example, a photorefractive material, a photochromic material, a third-order optical nonlinear material, an optical writing type spatial light modulator (hereinafter referred to as SL).
A material or element capable of writing interference fringes such as M) may be used. Although an SLM is assumed as the phase conjugate mirror 8a in FIG. 2 and an optical system of two-wave mixing is shown, in general, degenerate four-wave mixing is often used in the case of other materials.

Now, let us consider a case where the halogen lamp 21 irradiates the two-dimensional data 22 on the left side of the phase conjugate mirror 8a, and the transmitted light or reflected light is imaged on the phase conjugate mirror 8a by the lens 12a. Up to this point, the description has been given on the assumption that interference fringes can be recorded anywhere on the phase conjugate mirror 8a. As explained above, since photochromic materials and SLMs are sensitive to light coming from any surface, if two-dimensional data is written from the left with the generation of the phase conjugate wave as shown in FIG.
Of course, it is also exposed to that light. As a result, on the phase conjugate mirror 8a, only the portion of the two-dimensional data image that is not exposed to the irradiation light produces the phase conjugate wave, and the phase conjugate wave acts as the phase conjugate mirror. The phase conjugate wave E4 generated at this time just reproduces the two-dimensional data image on the ablator 23. Therefore,
If the lens 12b is arranged on the reading side so as to form an image-forming relationship with the aberrator 23, the conjugate image can be read without distortion.
In this example, the one that causes image distortion is generally described as the aberrator 23. However, since the multimode optical fiber is also a kind of the aberator, even if the multimode optical fiber is replaced, the data transmission between them can be performed. ..

Specific examples will be shown below. FIG. 3 shows the configuration of an embodiment of the present invention. In the figure, 1a and 1b are a pair of electronic circuit boards facing each other in parallel, and 2 is an electronic circuit board 1.
Optical circuit board disposed between a and 1b, 3 is a waveguide circuit on the optical circuit board 2, 4 is a laser diode (LD), 5 is a collimator, 6 is a photodiode array, and 7 is a light emitting diode (LED). Array, 8b is a phase conjugate mirror, 9c and 9d are beam splitters (BS), 10a and 1
Reference numeral 0b is a prism, and 12c and 12d are lenses.
Reference numeral 31 is a single-mode waveguide provided on the waveguide circuit 3, and 32 is a multi-mode waveguide provided on the waveguide circuit 3.

In FIG. 3, transmission data propagates from one electronic circuit board 1a to the other electronic circuit board 1b through the multi-mode waveguide 32. The configuration will be described in order from the light source along the propagation of light. A red light emitting LD having a wavelength of 670 nm is used as the LD 4 serving as a light source for the reference light and the transmitted light. A collimator 5 is placed at the emitting end of the LD 4 to collimate the light into substantially parallel light.

This collimated light is beam splitter 9c.
Incident on the multi-mode waveguide 32 on the waveguide circuit 3 as transmitted light, and the transmitted light is reflected on the prism 10b and guided on the single mode on the waveguide circuit 3 as reference light. Enter the waveguide 31. After propagating through the waveguide circuit 3, the respective lights are recombined to form the phase conjugate mirror 8
Enter b. That is, the transmitted light enters the phase conjugate mirror 8b through the prism 10a and the beam splitter 9d, and the reference light is collimated into parallel light by the lens 12d and then passes through the beam splitter 9d to enter the phase conjugate mirror 8b.

GRIN is used as the collimating lens 12d.
A lens (a gradient index lens) is used, and its length is exactly equal to the focal length. As another example of the optical waveguide circuit, a circuit in which the incident end (on the left side in FIG. 3) is a multimode waveguide and a Y-branch is divided into a multimode waveguide and a single mode waveguide on the way can be used. in this case,
The prism 10b can be omitted. Details of the phase conjugate mirror 8b will be described later, and the description will be continued along the flow of light.

The light modulated by the optical data of the LED array 7 on the electronic circuit board 1a passes through the beam splitter 9d, the prism 10a, the multi-mode waveguide 32, the beam splitter 9c, and the lens 12c, and then the photo on the electronic circuit board 1b. It is incident on the diode array 6. Therefore,
The parallel data on the electronic circuit board 1a is the electronic circuit board 1
This means that data has been transmitted in parallel up to b.

In this embodiment, the phase conjugate mirror 8b is realized by a spatial light modulator (SLM). The structure and operating principle of the SLM are as follows. The cross-sectional structure of the SLM is shown in FIG. In the figure, 111a and 111b are quartz substrates, 11
2a and 112b are transparent electrodes of indium tin oxide, 113 is an a-Si: H photoconductive film, 115a and 1
15b is an alignment film, 116 is a ferroelectric liquid crystal (FLC), 1
20 is a pulse power supply.

When the SLM is used as the phase conjugate mirror, the transmitted light and the reference light are incident from the FLC 116 side, and the FLC 11
At the interface between 6 and the photoconductive film 113, the reflected diffracted light is read out as a conjugate wave.

The outline of the operation is as follows. When a positive or negative voltage pulse is applied from the pulse power source 120 to the SLM 8b, most of the voltage is applied to the FLC 116 and the photoconductive film 1.
The pressure is divided during 13. Photoconductive film 11 in SLM
The role of 3 is to convert the intensity of light applied to it into electrical conductivity, whereby the applied voltage to the FLC 116 can be controlled by light. The FLC 116 is an optically birefringent material and can switch the optical axis according to the polarity of the applied voltage. As the FLC 116, for example, a surface-stabilized chiral smectic C phase (thickness 1 μm
The threshold value characteristic can be realized as the light input / output characteristic by using the element of m). By the action of the two layers 116 and 113, the polarization of the reflected read light can be changed by the write light. That is, if the interference fringes generated by the transmission light and the reference light are used as the writing light, a birefringence grating corresponding to the interference fringes is generated in the liquid crystal 116,
The reference light that is the writing light is diffracted, and the first-order diffracted light of the reference light comes out to the transmission light side as a phase conjugate wave.

In the embodiment of the present invention, since 3 μm thick a-Si: H is used as the photoconductive film 113, the photoconductive film /
The reflectance of the FLC interface is about 20%. As described above, this reflected diffracted light acts as a conjugate wave. SL
20 to 90 between the FLC 116 in the M and the photoconductive film 113.
%, A structure in which a dielectric mirror (not shown) is sandwiched is also possible. In this case, a bright conjugate image can be output although the sensitivity is lowered.

Although the case where the data light is not radiated to the photoconductive film side has been described above, if the photoconductive film 113 is irradiated with light having a sensitivity higher than that of the SLM as data light, the SLM can transmit the reference light and the transmission light. Since the optical response is saturated regardless of the light, interference fringes cannot be recorded, and diffracted light (conjugate wave) does not occur. That is, it becomes possible to write data in the phase conjugate mirror of the SLM with the data light. Where S
The threshold of the sensitivity of LM is 10 as a write pulse.
500 μW / when V, 200 μs pulse is applied
It was cm ² . In accordance with this, the intensity of the reference light and the transmitted light is 250 μW / cm ² , and the intensity of the two-dimensional data is 600 μ.
It was set to W / cm ² .

In the actually manufactured device, the LED array 7 includes 32 × 32 1024 red light emitting diodes.
An array in which the same number of photodiodes are arranged is used for the photodiode array 6 as well. Further, as the waveguides 31 and 32, a ridge type waveguide is formed on the upper part using a quartz substrate.
The single-mode waveguide 31 has a width of 4 μm and a height of 4 μm, and the multi-mode waveguide 32 has a width of 200 μm and a height of 2 μm.
It was set to 00 μm. According to this embodiment, the electronic circuit boards 1a, 1
It was confirmed that the data transmission between b can be performed by optical signals in parallel.

[0027]

As described above, according to the present invention,
Wiring between the electronic circuit boards can be performed with only two optical waveguides. In addition to transmission between circuit boards, the present invention can of course be applied to wiring within the boards. Further, the present invention can be applied not only to the connection between electronic circuits but also to the connection between optical devices such as an optical disk and an optical gate.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conventional configuration example.

FIG. 2 is a configuration diagram showing the principle of parallel optical transmission in the present invention.

FIG. 3 is a perspective view showing the configuration of an embodiment of the present invention.

FIG. 4 is a perspective view showing the structure of the SLM of FIG. 3 according to the present invention.

[Explanation of symbols]

 1a, 1b Electronic circuit board 2 Optical circuit board 3 Waveguide circuit 4 Laser diode 5 Collimator 6 Photodiode array 7 Light emitting diode array 8a, 8b Phase conjugate mirror 9a, 9b Beam splitter 10a, 10b Prism 12a, 12d Lens 21 Light source 22 Two-dimensional data 23 Averator 31 Single mode waveguide 32 Multi mode waveguide 111a, 111b Quartz substrate 112a, 112b Transparent electrode 113 Photoconductive film 115a, 115b Alignment film 116 Ferroelectric liquid crystal 120 Pulse power supply

Claims (3)

[Claims] 1. A phase conjugate mirror capable of writing two-dimensional data, a laser light source for driving the phase conjugate mirror, and a reference light obtained by separating a part of laser light emitted from the laser light source. A reference light waveguide circuit that transmits and irradiates the acting laser light to the phase conjugate mirror, and irradiates the phase conjugate mirror with laser light that acts as the remaining transmission light of the laser light emitted from the laser light source. And a transmission light waveguide circuit that retransmits the conjugate wave carrying the two-dimensional data generated by the phase conjugate mirror to the laser light source side, and a readout side that forms an image of the conjugate wave on the readout side. A parallel optical data transmission device comprising an optical system. 2. The parallel optical data transmission device according to claim 1, wherein the phase conjugate mirror is an optical writing type spatial light modulator using a photoconductive layer and a liquid crystal. 3. The parallel optical data according to claim 1, wherein the phase conjugate mirror is a degenerate four-wave mixing optical system made of a photorefractive crystal, a photochromic material, or an optical nonlinear material having third-order nonlinearity. Transmission equipment.