JPH05300125A - Optical information transmitter - Google Patents

Abstract

PURPOSE:To provide an optical transmission system which can simultaneously transmit the three kinds of information or more while adopting a polarizing plane multiplexing system. CONSTITUTION:This optical information transmitter for transmitting the plural kinds of digital signal information as the light intensity changed of the plural kinds of linearly polarized beams having respectively different polarizing planes is provided with an optical transmitting member 14 for transmitting plural linearly polarized beams, detector 16 to divide the plural kinds of linearly polarized beams transmitted through the optical transmitting member 14 into bidirectional polarized components orthogonal each other and to respectively detect the light intensity of the bidirectional polarized components, an arithmetic unit 18 to restore the plural kinds of digital signal information based on the detected information of the detector 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for transmitting information by light, and more particularly to an optical information transmission device for multiplexing information by dividing a plane of polarization.

[0002]

2. Description of the Related Art In optical communication using an optical fiber line, in addition to electrical signal multiplexing for expanding transmission capacity,
Various multiplex transmission systems utilizing the property of light have been devised. An optical wavelength division multiplexing method is known as a typical example. In this system, a plurality of lights each having a different wavelength are transmitted by one optical fiber, and signals are separated by using an optical multiplexer / demultiplexer. As another method, there is known a method of multiplexing and transmitting information by changing the polarization plane of light. This method utilizes the fact that linearly polarized light whose polarization planes differ from each other by 90 degrees does not interfere with each other and transmits different information on two linearly polarized lights of the same wavelength, which are transmitted through one optical fiber. As an optical communication technology for automobiles, the one disclosed in Japanese Patent Laid-Open No. 2-104141 is known.

[0003]

However, of the two methods described above, in the optical wavelength division multiplexing method using light of different wavelengths, the optical fiber has the property that the magnitude of loss changes depending on the wavelength of the light. Therefore, there is a problem in that the degree of loss of each transmitted signal is different. That is, with respect to the signal transmitted by the light of the optimum wavelength, the degree of loss of other signals becomes large, and the transmissible distance and speed are limited by the wavelength having the larger loss.

Further, in the polarization plane multiplexing system, except for two light components whose polarization planes are orthogonal to each other, they interfere with each other. Therefore, it is not possible to separate lights other than those orthogonal to each other. Only heavy multiplexing can be realized. Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to transmit optical information such that three or more types of information can be transmitted at the same time while adopting a polarization plane multiplexing method. To provide a method.

[0005]

In order to solve the above-mentioned problems and to achieve the object, an optical information transmission device of the present invention comprises a plurality of types of linearly polarized light having a plurality of different types of digital signal information and different polarization planes. An optical information transmission device for transmitting as light intensity change of light, comprising a photoconductive member for transmitting the plurality of linearly polarized light, and the plurality of types of linearly polarized light transmitted through the photoconductive member. Detection means for dividing light into polarization components in two directions orthogonal to each other and detecting the light intensities of the polarization components in the two directions respectively, and restoring the plurality of types of digital signal information based on the detection information of the detection means It is characterized by comprising a calculation means for

Further, in the optical information transmission device according to the present invention, the plurality of types of linearly polarized light are four types of linearly polarized light, and the polarization planes of the three types of polarized light are:
The polarization plane of the remaining one polarized light is 30 degrees, 60 degrees, and 9 degrees, respectively.
It is characterized by forming an angle of 0 degree. In addition, in the optical information transmission device according to the present invention, the plurality of types of linearly polarized light are three types of linearly polarized light, and the polarization planes of the two types of polarized light are the remaining one polarized light. It is characterized in that they make an angle of 45 degrees and 90 degrees with the plane of polarization of, respectively.

[0007]

As described above, since the optical information transmission device according to the present invention is configured, the light intensity of each polarized light is separated into the components in two directions orthogonal to each other, and the combination of the light intensity of these components is combined. By calculating, it becomes possible to separate three or more types of digital signals.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an optical information transmission device according to an embodiment. In FIG. 1, a plurality of types of information signals to be transmitted are output from the information source 12 as optical signals having different polarization planes. As shown in FIG. 2, these optical signals are output from the information source 12 as digital signals due to changes in light intensity, and transmitted to the destination via the optical fiber 14. A detector 16 is connected to the tip of the optical fiber 14 to separate optical signals having different polarization planes into polarized light components in two directions orthogonal to each other and detect the light intensities in the two directions. The detection device 16 further includes the detection device 1
An arithmetic unit 18 for separating a plurality of types of information signals from the light intensities of the polarization components in the two directions detected by 6 is connected.

Next, a method of separating a plurality of types of information signals from the optical signals transmitted with the polarization planes different from each other as described above will be described. FIG. 3 is a diagram for explaining the principle of separating this information signal. 3 is 4
A case is shown in which various types of information signals are transmitted as optical signals A, B, C, and D having linear polarization states with different polarization planes. The polarization planes of the linearly polarized light of the optical signal A and the optical signal D are orthogonal to each other, and the polarization plane of the optical signal B forms an angle of 30 ° with the polarization plane of the optical signal A. The plane of polarization of the signal C also makes an angle of 60 ° with the plane of polarization of the optical signal A.

Here, the transmitted optical signals A, B, C, D
Is a digital signal composed of "1" each having a specific amplitude I and "0" having an amplitude 0. In this case, two polarization planes orthogonal to each other (in this embodiment, two polarization planes orthogonal to each other are referred to as a polarization plane of the optical signal A and an optical signal D).
Amplitude component (light intensity component)
When the optical signals do not interfere with each other, the amplitude component I ₀ I ₀ = [A] I + [B] Icos 30 ° + [C] of the optical signal A in the polarization plane direction (polarization angle 0 ° direction). Icos60 ° Amplitude component I ₉₀ I ₉₀ = + [B] Isin30 ° + [C] Isin60 ° + [D] I in the polarization plane direction (polarization angle 90 ° direction) of the optical signal D. However, [A], [B], [C], and [D] are digital signal components of the optical signals A, B, C, and D, that is, "1", respectively.
Or "0".

Combination of these signal amplitudes (I _0, I ₉₀ )
, The information of the optical signals A, B, C, D can be separated. For example, if (I _0, I ₉₀ ) = (1 / 2,1 + sin60 °), as shown in FIG. 3, the digital signal component of each optical signal is A: “0”, B: "0", C: "1", D:
It is "1". There is a one-to-one correspondence between the amplitude and the transmission content, and the transmission content can be uniquely determined. In order to prevent interference of optical signals, the light sources may be independent.

As described above, according to the optical information transmitting apparatus of this embodiment, a plurality of information to be transmitted is transmitted as a digital signal by using linearly polarized light having different polarization planes,
By detecting the light intensity of each optical signal as a combination of the light intensity components in two directions orthogonal to each other, even if three or more pieces of information are transmitted at one time by one optical transmission line, a plurality of pieces of information can be detected. It becomes possible to separate.

The present invention can be applied to modifications and variations of the above embodiments without departing from the spirit of the present invention. For example, in the above embodiment, the angles formed by the polarization planes of the four optical signals are 0 °, 30 °, 60 ° and 9 °, respectively.
Although set to 0 °, in addition to this, the angles formed by the polarization planes of the three optical signals are 0 °, 45 °, and 90 °.
It may be set to. Even in this case, there is a one-to-one correspondence between the amplitude of the optical signal and the transmission content, and the transmission content can be uniquely determined. Further, other combinations are possible as long as the combination of the amplitude of the optical signal and the transmission content is in a one-to-one correspondence.

[0014]

As described above, according to the optical information transmission device of the present invention, the light intensity of each polarized light is separated into the components in two directions orthogonal to each other, and the combination of the light intensities of these components is calculated. By doing so, it becomes possible to separate three or more types of digital signals.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an optical response transmission device according to an embodiment.

FIG. 2 is a diagram showing a transmitted digital signal.

FIG. 3 is a diagram for explaining the principle of separating this information signal.

[Explanation of symbols]

 12 information source 14 optical fiber 16 detector 18 arithmetic unit

Claims (3)

[Claims] 1. An optical information transmitting device for transmitting a plurality of types of digital signal information as a change in the light intensity of a plurality of types of linearly polarized light having different polarization planes, and transmitting the plurality of linearly polarized light. And a plurality of kinds of linearly polarized light transmitted through the photoconductive member are divided into polarization components in two directions orthogonal to each other, and the light intensities of the polarization components in the two directions are respectively detected. An optical information transmission device, comprising: a detection unit that performs the above-described detection; and a calculation unit that restores the plurality of types of digital signal information based on the detection information of the detection unit. 2. The plurality of types of linearly polarized light are four types of linearly polarized light, and the polarization planes of the three types of polarized light are 30 degrees and the polarization plane of the remaining one polarized light, respectively. , 60
The optical information transmission device according to claim 1, wherein the optical information transmission device forms an angle of 90 degrees. 3. The plurality of types of linearly polarized light are three types of linearly polarized light, and the polarization planes of the two types of polarized light are 45 degrees and the polarization planes of the remaining one polarized light, respectively. , 90
The optical information transmission device according to claim 1, wherein the optical information transmission device forms an angle of degrees.