JPH11234206A - Photoelectric conversion module and optical communication system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to transmit an optical signal in parallel by dividing a white light into an S polarized light and a P polarized light, converting an electric signal into the optical signal, converting the received optical signal into the electric signal and performing transmission and reception of the optical signal with the outside. SOLUTION: An S polarized light transmission filter 8 is arranged on a light path of a white light from a white light source 7, only the S polarized light in a linearly polarized transmits, is reflected by a polarized beam splitter 2, and propagates for a spatial optical modulation element 4. Immediately before this element, a dichroic mirror 3 is arranged in the light. Each color light is modulated into an (S+P) polarized light by a transmission signal generated by reflection type spatial optical modulation elements 4R, 4G and 4B in a spatial optical modulation element driving circuit 10, is reflected, and a color light is synthesized while green is letting the dichronic mirror 3 transmit and red and blue are reflecting it. The (S+P) polarized light has only the P polarized light transmitted by the polarized beam splitter 2, it transmits a lens 6, is compressed into a spot optimal for inputting to a optical fiber, and is outputted to an external optical fiber cable 90.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion module and an optical communication system using the same.

[0002]

2. Description of the Related Art When transmitting digital data to a remote place, a transmission method using light is often used because of its strength against electric noise and the advantage that it can be used over a long distance. In order to convert an electric signal of digital data into an optical signal, a method of turning light on and off corresponding to bits 1 and 0 in a bit unit constituting digital data is generally employed. For example, when transmitting an image, the image is scanned, converted into a one-dimensional electrical signal, and then further converted into a one-dimensional optical signal and transmitted.

[0003]

In such one-dimensional optical signal transmission, there is a problem that the transmission takes a lot of time because the transmission is performed in units of bits. In the case where an imaging device that does not require a scanning function, which is currently being researched at each research institute, that is, an element that transfers all pixels in parallel like the human eye will be put into practical use in the future, this one-dimensional transfer will not be possible. It becomes a bigger neck.

The present invention has been made to solve such a problem, and has as its object to provide a photoelectric conversion module for transmitting optical signals in parallel and an optical communication system using the same.

[0005]

Means for Solving the Problems To solve the above problems,
In the photoelectric conversion module and the optical communication system using the same according to the present invention, the white light input means, the polarized light splitting means for separating white light into S-polarized light and P-polarized light, and the electric signal are transmitted. Transmitting means for converting to an optical signal and transmitting, and receiving means for converting the received optical signal to an electric signal,
The configuration of the photoelectric conversion module 100 including an optical signal transmission unit that transmits and receives the optical signal to and from the outside is provided.

According to the second aspect of the present invention, the white light input means, the polarized light branching means for separating the white light from the white light input means into S-polarized light and P-polarized light, and the destination of the S-polarized light or P-polarized light And modulates and reflects the S-polarized light or the P-polarized light in accordance with a first electric signal given from the outside.
Optical signal generating means for generating the first optical signal, an optical signal transmitting means for transmitting the first optical signal to the outside, and transmitting the second optical signal from the outside to the inside; The photoelectric conversion module 100 includes an electric signal generation unit that converts the second optical signal split into polarized light and P-polarized light into an electric signal.

According to a third aspect of the present invention, in the photoelectric conversion module 100 according to the first or second aspect, the white light input means includes: a white light source 7;
And a linearly polarized light transmitting means for transmitting only polarized light. According to a fourth aspect of the present invention, in the photoelectric conversion module 100 according to the first or second aspect, the polarized light splitting means has a polarization beam splitter 2.

According to a fifth aspect of the present invention, in the photoelectric conversion module according to the first or second aspect, the transmitting means for converting the electric signal into an optical signal and transmitting the optical signal includes a dichroic mirror 3, a spatial light modulator 4, And the receiving means for converting the received optical signal into an electric signal includes the dichroic mirror 3 and the light receiving element 5.

According to a sixth aspect of the present invention, in the photoelectric conversion module 100 according to the first or second aspect, the optical signal transmitting means includes a lens 6 and an optical fiber cable 9.
0 is connected to the housing of the photoelectric conversion module 100. In the invention according to claim 7, the white light source 7, a linearly polarized light transmitting means for passing only S-polarized light out of the white light from the white light source 7, and a polarized light for reflecting the S-polarized light transmitted through the linearly polarized light transmitting means. A beam splitter 2, a first dichroic mirror 3 disposed at a destination of the reflected s-polarized light, and separating the s-polarized light into red, green, and blue first color lights; A spatial light modulator 4 that converts each color light and a transmission electric signal given from outside into a transmission light signal for each color light having an S-polarized light component and a P-polarized light component and reflects the same, Optical signal generating means for combining transmission optical signals by the first dichroic mirror 3 and generating a combined optical signal of a color consisting of a second S-polarized light and a first P-polarized light for each color; Only the first P-polarized light of the combined optical signal is a polarized beam. Transmitting P-polarized light generating means for transmitting the transmitting P-polarized light through the splitter 2 and guiding the transmitting P-polarized light to the external optical fiber cable 90 and guiding the received S-polarized light sent from the outside to the inside A signal transmission unit, and a reception S-polarized light transmission unit that reflects the received S-polarized light in a direction different from both the optical signal generation unit and the white light source 7 by a polarization beam splitter to generate a third S-polarized light. , A second dichroic mirror 3 disposed at a destination of the third S-polarized light and separating the third S-polarized light into red, green, and blue second color lights; The configuration of the photoelectric conversion module 100 includes a light receiving element for each color that converts each color light into an electric signal.

According to an eighth aspect of the present invention, in the photoelectric conversion module 100 according to any one of the first to sixth aspects, the photoelectric conversion module 100 further includes a polarization direction switching means for switching the polarization directions of the S-polarized light and the P-polarized light, and the switching means is provided. 200. According to a ninth aspect of the present invention, in the photoelectric conversion module 100 according to the eighth aspect, the polarization direction changing means is
The photoelectric conversion module 200 is characterized by being constituted by a half-wave plate 20.

According to a tenth aspect of the present invention, the white light source 7
Linearly polarized light transmitting means for passing only the S-polarized light (first S-polarized light) of the white light from the white light source 7, and a polarized beam for reflecting the first S-polarized light transmitted through the linearly polarized light transmitting means A splitter 2 and a first dichroic mirror 3 disposed at a destination of the reflected first S-polarized light and separating the first S-polarized light into red, green, and blue first color lights And spatial light modulation for converting and reflecting the separated first color lights and a transmission electric signal given from the outside into transmission light signals for each color light having an S-polarized light component and a P-polarized light component. The element 4 and the transmission light signal for each color light are combined by the first dichroic mirror 3 to generate a combined light signal of the color composed of the second S-polarized light and the first P-polarized light for each color. An optical signal generating means for generating the first P-polarized light of the color-combined optical signal. And transmitting P-polarized light generating means but which has transmitted through the polarization beam splitter 2 transmits P-polarized light is generated,
The transmission P-polarized light is converted into transmission S-polarized light by installing a half-wave plate 20 between the polarization beam splitter 2 and the optical signal transmitting means and exchanging the polarization directions of the S-polarized light and the P-polarized light. Transmission light generation means, and optical signal transmission means for guiding transmission S-polarized light to an external optical fiber cable 90 and guiding reception P-polarized light sent from the outside to the inside;
Received light generating means for converting the received P-polarized light into third S-polarized light by the half-wave plate, and reflection by a polarizing beam splitter in a direction different from both the optical signal generating means and the white light source. Receiving S-polarized light transmitting means for generating the third S-polarized light, and disposed at a destination of the third S-polarized light;
A second dichroic mirror 3 for separating the third S-polarized light into red, green and blue second color lights, and a light receiving element for each color for converting the separated second color lights into electric signals 5).

According to an eleventh aspect of the present invention, in the photoelectric conversion module 100 according to the first to seventh aspects, a plurality of bits are photoelectrically converted simultaneously in parallel. According to a twelfth aspect of the present invention, in the photoelectric conversion module 100 according to any one of the first to seventh aspects, an entire image having a plurality of pixels of halftone density is photoelectrically converted simultaneously and in parallel.

According to the thirteenth aspect of the present invention, the tenth aspect of the present invention provides
In the photoelectric conversion module 200 described above, a plurality of bits are simultaneously subjected to photoelectric conversion in parallel. According to a fourteenth aspect of the present invention, in the photoelectric conversion module 200 according to the eighth to tenth aspects, an entire image having a plurality of pixels of halftone density is photoelectrically converted simultaneously and in parallel.

According to a fifteenth aspect of the present invention, there is provided a photoelectric conversion module according to the third, seventh, and tenth aspects.
0 and 200, the linearly polarized light transmitting means is a polarizing filter. According to a sixteenth aspect, in the photoelectric conversion modules 100 and 200 according to the fifteenth aspect, the polarization filter is an S-polarized light transmission filter 8.

According to a seventeenth aspect of the present invention, there is provided a photoelectric conversion module according to the third, seventh, and tenth aspects.
0 and 200, the linearly polarized light transmission means is a polarization transmission optical system 300 including a polarization beam splitter 310, a mirror 320, and a half-wave plate 330.

According to the eighteenth aspect of the present invention, the first photoelectric conversion module 100 according to the eleventh aspect and the thirteenth aspect are provided.
A second photoelectric conversion module 200 described in
The optical communication system has an optical fiber cable 90 for connecting between the photoelectric conversion module 100 and the second photoelectric conversion module 200. According to the nineteenth aspect, the first photoelectric conversion module 100 according to the twelfth aspect, the second photoelectric conversion module 200 according to the fourteenth aspect, the first photoelectric conversion module 100 and the second An optical communication system having an optical fiber cable 90 connecting between the photoelectric conversion modules 200 was adopted.

In the twentieth aspect, the first photoelectric conversion module 100 uses P-polarized light for transmitting means and uses S-polarized light for receiving means, and receives P-polarized light using S-polarized light for transmitting means. Photoelectric conversion module 20 used for means
0, and an optical communication system including an optical fiber cable 90 connecting between the first photoelectric conversion module 100 and the second photoelectric conversion module 200.

According to a twenty-first aspect of the present invention, in the optical communication system of the eighteenth and nineteenth aspects, a plurality of bits are simultaneously transferred in parallel. In the invention of claim 22, claim 18 and claim 1
9. The optical communication system according to item 9, wherein an entire image having a plurality of pixels of halftone density is simultaneously transferred in parallel.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a P-polarized light transmission / S-polarized light reception photoelectric conversion module 100 according to the present invention, and corresponds to claims 1 to 7, 15, and 16. First, transmission will be described. An S-polarized light transmission filter 8 is arranged on the optical path of the white light emitted from the white light source 7,
Only S-polarized light of the linearly polarized light is transmitted.

Here, the linearly polarized light will be briefly supplemented. Consider a case where light is obliquely incident on a certain surface. Linearly polarized light whose electric vector oscillates in the plane of incidence (the plane created by the normal line and the light beam) is P-polarized light, and linearly polarized light whose electric vector oscillates in the direction perpendicular to the plane of incidence is S-polarized light. Light. That is, the polarization directions of the S-polarized light and the P-polarized light are orthogonal to each other. Incidentally, according to Kozo Ishiguro's "Optics", S of S-polarized light is an acronym of Senkrecht (vertical), and P of P-polarized light is an acronym of Parallel (parallel).

The S-polarized light transmitted through the S-polarized light transmission filter 8 is reflected by the polarization beam splitter 2, bent at a right angle, and travels to the spatial light modulator 4. Immediately before the spatial light modulator 4, the dichroic mirror 3 for separating light into red, green, and blue light is disposed. The dichroic mirror 3 is configured such that a mirror that reflects red and a mirror that reflects blue cross each other, and each color light goes to the reflective spatial light modulators 4R and 4B. The green color light transmitted through the dichroic mirror 3 travels to the reflective spatial light modulator 4G. The respective color lights are (S + P) in each of the reflection type spatial light modulation elements (4R, 4G, 4B) by the transmission signal generated by the spatial light modulation element driving circuit 10.
The light is modulated into polarized light and reflected. The reflected (S + P) -polarized light passes through the dichroic mirror 3 again, and red and blue are reflected while red and blue are reflected to combine color lights. Synthesized (S +
The P-polarized light passes through the lens 6 and is condensed into an optimum spot for input to the optical fiber by passing through the lens 6, and is output to the external optical fiber cable 90.

In this way, the data transmission electric signal is converted into "modulated P-polarized light" and transmitted to the outside.
Next, reception will be described. "S modulated by data transmitted from outside through the optical fiber cable 90"
The “polarized light” is incident on the polarization beam splitter 2 via the lens 6. The S-polarized light reflected here goes to the light receiving element 5. Just before the light receiving element 5, the dichroic mirror 3 is arranged like the spatial light modulation element 4.
Each color light separated by the dichroic mirror 3 is converted into an electric signal by a light receiving element (5R, 5G, 5B) and sent to the outside via a waveform shaping circuit 11.

The "modulated S-polarized light" input from the outside in this manner is converted into an electric signal. FIG. 2 is a diagram showing an S-polarized light transmitting / P-polarized light receiving photoelectric conversion module 200 according to the present invention.
It corresponds to. FIG. 2 shows the configuration of the polarization beam splitter 2.
The configuration is the same as that of FIG. 1 except for the half-wave plate 20 inserted between the lens and the lens 6.

The half-wave plate has the property of changing the direction of linearly polarized light by 90 degrees, and transmits linearly polarized light,
If the linearly polarized light is S-polarized light, the polarization direction can be equal to the P-polarized light, and if the linearly polarized light is P-polarized light, the polarization direction can be equal to the S-polarized light.
By inserting the half-wave plate 20, transmission / reception reverse to that of the photoelectric conversion module of FIG. 1, that is, a photoelectric conversion module of S-polarized light transmission / P-polarized light reception can be realized.

FIG. 3 is a diagram showing an embodiment of a photoelectric conversion module of the present invention and an optical communication system using the same, and corresponds to claims 18 to 22. The photoelectric conversion module 100 does not have the half-wave plate 20, the photoelectric conversion module 200 has the half-wave plate 20, and the optical fiber 90. Thus, the P-polarized light transmission / S-polarized light reception photoelectric conversion module and the S-polarized light transmission /
By using a pair of P-polarized light receiving photoelectric conversion modules, 1
An optical communication system capable of transmitting and receiving by the number of fibers can be realized.

FIG. 4 is a diagram for explaining a unit for sending data in the present invention, and corresponds to claims 11 to 14. The data of the spatial light modulator 4 is transmitted to the light receiving element 5 via the optical fiber 90. FIG. 4A is a diagram showing a minimum unit of transmission. The data of 1 and 0 is represented by the change in density on the entire surface of the spatial light modulator 4. This is one-bit transfer at a time, which is equivalent to conventional optical communication.

FIG. 4B shows two bits, and FIG.
4 shows simultaneous transmission of 4 bits. Two or four bits are sent in parallel. FIG. 4 (d) shows the simultaneous transmission of many bits. In FIG. 4, binary values of 0 or 1 are shown, but each bit (pixel) can be multi-valued. For example,
If one pixel is represented by 8 bits, gradations from 0 to 255 can be represented. By making the values in FIG. 4D multi-valued, the entire frame of the color image represented by the spatial light modulators 4R, 4G, and 4B is simultaneously paralleled. Image transmission system. FIG.
Which of (a) to (d) is to be used may be determined according to the purpose of use and the degree of data deterioration.

By introducing such analog transmission into an optical communication system, an ultra-high-speed communication system becomes possible.
Further, the present invention is more effective if the spatial light modulation element 4 for transmission, the light receiving element 5 for reception and the external device are not one-dimensional electric signals but parallel electric signals. An example of this is an example in which a two-dimensional image is transmitted optically without scanning and two-dimensionally transmitted and displayed as it is at a remote location.

The S-polarized light transmission optical system 300 (FIG. 17) shown in FIG. 5 as a means for transmitting linearly polarized light more efficiently than the S-polarized light transmission filter 8 (corresponding to claim 16) shown in FIGS. Will be described. This S polarized light transmission optical system 3
No. 00 changes the position of the half-wave plate 330 of the system described in the document “Optics, Vol. 25, No. 6, page 303, FIG. 3: Polarization conversion optical system” so that S-polarized light is transmitted instead of P-polarized light. It was made. In FIG. 5, white light (S + P) from the white light source 7 incident from the upper surface of the figure is transmitted through the polarization beam splitter 310 as P-polarized light and reflected as S-polarized light. The reflected S-polarized light travels to the mirror 320, and is further reflected and emitted to the lower surface in the figure. P-polarized light is a half-wave plate 330
Then, the linear polarization direction is rotated by 90 degrees and becomes equal to the polarization direction of the S-polarized light.

As described above, by inserting the S-polarized light transmission optical system 300 instead of the S-polarized light transmission filter 8 at the same position as the S-polarized light transmission filter 8 in FIGS. P-polarized light, which has been absorbed and lost, can also be used, resulting in high efficiency.

[0031]

As described above, according to the present invention, since data can be transmitted in parallel, high-speed communication can be performed as compared with a conventional optical communication system which is one-dimensional optical signal transmission. If the present invention is used for image transmission, a high-speed image transmission system that transmits the entire image frame in parallel can be realized.
Further, by using the S-polarized light transmission optical system for the linearly polarized light transmission means, a system with high energy efficiency can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a P-wave transmission / S-wave reception photoelectric conversion module of the present invention.

FIG. 2 is a block diagram of an S-wave transmission / P-wave reception photoelectric conversion module according to the present invention.

FIG. 3 is a block diagram of an optical communication system according to the present invention.

FIG. 4 is a diagram illustrating a unit for sending data.

FIG. 5 is a sectional view of a polarization conversion optical system.

[Explanation of symbols]

Reference Signs List 2 polarizing beam splitter 3 dichroic mirror 4 spatial light modulator 5 light receiving element 6 lens 7 white light source 8 S polarized light transmission filter 10 spatial light modulator driving circuit 11 waveform shaping circuit (electric data receiver) 20 1/2 wavelength plate 90 Optical fiber cable 91 Connector 100 P-polarized light transmission / S-polarized light reception photoelectric conversion module 200 S-polarized light transmission / P-polarized light reception photoelectric conversion module 300 S-polarized light transmission optical system 310 Polarized beam splitter 320 Mirror 330 1/2 wavelength plate

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 7/22

Claims (22)

[Claims] 1. A white light input means, which outputs white light to S-polarized light and P light.
Polarized light splitting means for splitting polarized light into light, transmitting means for converting an electric signal into an optical signal for transmission, receiving means for converting a received optical signal into an electric signal, and optical signal transmission for transmitting / receiving the optical signal to / from the outside Means, and a photoelectric conversion module comprising: 2. A white light input means, a polarized light splitting means for splitting white light from the white light input means into S-polarized light and P-polarized light, and arranged at a destination of the S-polarized light or P-polarized light. An optical signal generating means for modulating and reflecting the S-polarized light or P-polarized light to generate a first optical signal in accordance with a first electric signal supplied from outside; And an optical signal transmitting means for transmitting a second optical signal from the outside to the inside, and the second optical signal split into S-polarized light and P-polarized light by the polarized light branching means, A photoelectric conversion module comprising: an electric signal generation unit that converts the electric signal into an electric signal. 3. The photoelectric conversion module according to claim 1, wherein said white light input means comprises a white light source and a linearly polarized light transmitting means for passing only S-polarized light or P-polarized light. A photoelectric conversion module characterized by being performed. 4. The photoelectric conversion module according to claim 1, wherein said polarized light splitting means is constituted by a polarized beam splitter. 5. The photoelectric conversion module according to claim 1, wherein said transmitting means for converting said electric signal into an optical signal and transmitting said optical signal comprises a dichroic mirror and a spatial light modulator, and A photoelectric conversion module, wherein the receiving means for converting the converted optical signal into an electric signal includes a dichroic mirror and a light receiving element. 6. The photoelectric conversion module according to claim 1, wherein said optical signal transmission means comprises a lens and a connector for connecting an optical fiber cable to a housing of the photoelectric conversion module. A photoelectric conversion module characterized by the above-mentioned. 7. A white light source, linearly polarized light transmitting means for passing only S-polarized light (first S-polarized light) of white light from the white light source, and transmitting the linearly polarized light transmitting means. A polarizing beam splitter that reflects the first S-polarized light and a destination of the reflected first S-polarized light, and converts the first S-polarized light into red, green, and blue first light. A first dichroic mirror that separates each color light into a first color light and a transmission electric signal supplied from the outside to input a first dichroic mirror to separate each color light having an S-polarized light component and a P-polarized light component. A spatial light modulator that converts the light into a transmission light signal and reflects the light,
The transmission light signal for each color light is synthesized by the first dichroic mirror, and the second S-polarized light for each color and the first P
An optical signal generating means for generating an optical signal composed of a color composed of polarized light, and a first P among the optical signals composed of the colors;
A transmission P-polarized light generating means for generating transmission P-polarized light by transmitting only polarized light through the polarization beam splitter;
Reception S that guides polarized light to the outside and is sent from outside
An optical signal transmitting means for guiding the polarized light inside, and the received S-polarized light reflected by the polarizing beam splitter in a direction different from that of the optical signal generating means and the white light source to form a third S-polarized light Receiving S-polarized light transmitting means for generating the third S-polarized light;
A second dichroic mirror that separates the S-polarized light into red, green, and blue second color lights, and a light receiving element for each color that converts the separated second color lights into electric signals. A photoelectric conversion module, comprising: 8. The photoelectric conversion module according to claim 1, further comprising a polarization direction switching means for switching the polarization directions of the S-polarized light and the P-polarized light. 9. The photoelectric conversion module according to claim 8, wherein said polarization direction switching means comprises a half-wave plate. 10. A white light source, linearly polarized light transmitting means for passing only S-polarized light (first S-polarized light) of white light from the white light source, and said linearly polarized light transmitting means. A polarizing beam splitter that reflects the first s-polarized light, and a polarizing beam splitter that is disposed at a destination of the reflected first s-polarized light and converts the first s-polarized light into red, green, and blue first colors A first dichroic mirror that separates light into light, and a transmission light for each color light having an S-polarized light component and a P-polarized light component by inputting the separated first color light and a transmission electric signal given from outside. A spatial light modulator that converts the signal into a signal and reflects the signal,
The transmission light signal for each color light is synthesized by the first dichroic mirror, and the second S-polarized light for each color and the first P
An optical signal generating means for generating an optical signal composed of a color composed of polarized light, and a first P among the optical signals composed of the colors;
Transmitting P-polarized light generating means in which only polarized light is transmitted through the polarizing beam splitter to generate transmitting P-polarized light, and a half-wave plate provided between the polarizing beam splitter and the optical signal transmitting means to provide S-polarized light And a transmission light generating means for converting the transmission P-polarized light into transmission S-polarized light by exchanging the polarization direction of the P-polarized light with the transmission light. The transmission S-polarized light is guided to an external optical fiber cable, and sent from the outside. An optical signal transmitting means for guiding incoming P-polarized light to the inside, a received light generating means for converting the received P-polarized light into a third S-polarized light by the half-wave plate, and a polarization beam splitter. , A receiving S which is reflected in a direction different from both the optical signal generating means and the white light source to generate third S-polarized light.
Polarized light transmitting means, and a second dichroic mirror disposed at a destination of the third S-polarized light and separating the third S-polarized light into red, green, and blue second color lights, A light-receiving element for each color that converts the separated second color light into an electric signal. 11. The photoelectric conversion module according to claim 1, wherein a plurality of bits are simultaneously subjected to photoelectric conversion in parallel. 12. A photoelectric conversion module according to claim 1, wherein an entire image having a plurality of pixels of halftone density is photoelectrically converted in parallel at the same time. 13. A photoelectric conversion module according to claim 8, wherein a plurality of bits are simultaneously subjected to photoelectric conversion in parallel. 14. The photoelectric conversion module according to claim 8, wherein an entire image having a plurality of pixels of halftone density is photoelectrically converted in parallel at the same time. 15. The third, seventh and tenth aspects of the present invention.
3. The photoelectric conversion module according to claim 1, wherein the linearly polarized light transmitting means is a polarizing filter. 16. The photoelectric conversion module according to claim 15, wherein said polarization filter is an S-polarized light transmission filter. 17. The method of claim 3, 7, or
3. The photoelectric conversion module according to claim 1, wherein the linearly polarized light transmitting means is a polarized light transmission optical system including a polarizing beam splitter, a mirror, and a half-wave plate. 18. A first photoelectric conversion module according to claim 11, a second photoelectric conversion module according to claim 13, the first photoelectric conversion module, and the second photoelectric conversion module. And an optical fiber cable connecting between the two. 19. The first photoelectric conversion module according to claim 12, the second photoelectric conversion module according to claim 14, the first photoelectric conversion module, and the second photoelectric conversion module. And an optical fiber cable connecting between the two. 20. A first photoelectric conversion module that uses P-polarized light for transmitting means and uses S-polarized light for receiving means, and a second photoelectric conversion module that uses S-polarized light for transmitting means and uses P-polarized light for receiving means.
An optical communication system comprising: a photoelectric conversion module according to (1), and an optical fiber cable connecting between the first photoelectric conversion module and the second photoelectric conversion module. 21. The optical communication system according to claim 18, wherein a plurality of bits are simultaneously transferred in parallel. 22. The optical communication system according to claim 18, wherein an entire image having a plurality of pixels of halftone density is simultaneously transferred in parallel.