JP2014140087A - Multiplexed optical transmission device, transmitter, receiver, and multiplexed optical transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that signals cannot be multiplexed exceeding a given number of wavelengths because signals which can be multiplexed are determined by a spectrum width.SOLUTION: The present invention comprises: an optical transmitter provided with a plurality of light sources emitting rays of light differing in wavelength from each other, a plurality of polarization elements for making a plurality of rays of light from the plurality of light sources into rays of light in two polarized directions, a plurality of optical signal modulators provided corresponding to the plurality of polarization elements and having light and information signal from each polarization element inputted thereto, and a signal multiplexing unit for multiplexing optical signals from the plurality of optical signal modulators; and an optical receiver provided with a signal separation unit for separating the optical signal received from the optical transmitter for each wavelength, and a plurality of polarization controllers for allowing respectively a ray of light in one polarized direction among rays of light in at least two polarized directions among the separated optical signals to pass through.

Description

  The present invention relates to a multiplexed optical transmission apparatus, a transmitter, a receiver, and a multiplexed optical transmission method, and more particularly to a multiplexed optical transmission apparatus, a transmitter, a receiver, and a multiplexed optical transmission method that perform optical transmission by multiplexing signals by wavelength multiplexing. .

  FIG. 1 is a block diagram showing a configuration example of a multiplex optical transmission apparatus as a background art. In FIG. 1, a long-distance optical transmission transmitter 101 converts a signal from the optical transmission apparatus transmitter 1 into an optical signal having a required wavelength (first wavelength) and optical output for long-distance optical communication, and performs signal multiplexing. Output to the unit 103. Similarly, the long-distance optical transmission transmitter 102 converts the signal from the optical transmission apparatus transmitter 2 into an optical signal having a required wavelength (second wavelength) and optical output for long-distance optical communication, and a signal multiplexing unit. To 103.

  The optical signal output from the signal multiplexing unit 103 passes through the optical transmission path 104 and is separated into each wavelength by the signal separation unit 105. The signal of the first wavelength is received by the long-distance optical transmission receiver 106 and transmitted to the optical transmission device receiver 3. Similarly, the signal of the second wavelength is received by the long-distance optical transmission receiver 107 and transmitted to the optical transmission device receiver 4.

  Thus, the long-distance optical communication device is inserted between the optical transmission device transmitter 1 and the optical transmission device receiver 3 and between the optical transmission device transmitter 2 and the optical transmission device receiver 4, so that the section is long distance away. It is generally known that communication on the Internet is possible.

  As a technique related to the multiplexed optical transmission apparatus, Patent Document 1 discloses an optical signal including a first sideband and a first optical carrier wave of the same polarization, and a second sideband and a second optical carrier wave. An optical communication system is described that includes an optical transmitter to generate and an optical receiver that receives an optical signal and converts it to an electrical signal after removing the first or second optical carrier. Patent Document 2 describes a method for determining a discrimination threshold of a received signal input from an optical transmission line.

JP 2010-212835 (paragraphs 0018-0022, 0029, etc.) JP 2002-9699 A (paragraphs 0025-0026, etc.)

  In the above multiplexed optical transmission apparatus, signals are multiplexed by wavelength multiplexing. However, since the signals that can be multiplexed are determined by the width of the spectrum, it is impossible to multiplex more than a predetermined number of wavelengths.

A typical multiple optical transmission apparatus according to the present invention is provided corresponding to a plurality of light sources that emit light having different wavelengths, and the light from the plurality of light sources is transmitted in at least two directions. A plurality of polarization elements having a polarization direction of light, a plurality of optical signal modulators provided corresponding to the plurality of polarization elements, and respectively receiving light from each polarization element and an information signal, and the plurality An optical transmitter comprising: a signal multiplexing unit that multiplexes the optical signal from the optical signal modulator;
A signal separation unit that separates an optical signal received from the optical transmitter for each wavelength; and a light in one polarization direction among the light in the polarization directions in at least two directions among the optical signals that have been separated. An optical receiver comprising a plurality of polarization controllers that pass;
Is a multiplex optical transmission device.

  A typical optical transmitter according to the present invention is provided corresponding to a plurality of light sources that emit light having different wavelengths, and the light from the plurality of light sources in at least two directions. A plurality of polarizing elements for making light in the polarization direction, a plurality of optical signal modulators provided corresponding to the plurality of polarizing elements, to which an optical signal and an information signal from each polarizing element are respectively input, and the plurality And a signal multiplexing unit that multiplexes optical signals from the optical signal modulator.

  A typical optical receiver according to the present invention includes a signal separation unit that receives an optical signal polarized in at least two polarization directions and multiplexed into a plurality of wavelengths, and separates the optical signal for each wavelength. And a plurality of polarization controllers that respectively pass light of one of the at least two polarization directions of the separated optical signal.

In a typical multiplexed optical transmission method according to the present invention, in an optical transmitter, light having different wavelengths is emitted from a plurality of light sources, and the light from the plurality of light sources is light having at least two polarization directions. And performing signal modulation using polarized light and an information signal, and multiplexing and transmitting a plurality of signal-modulated optical signals,
In the optical receiver, the optical signal received from the optical transmitter is subjected to signal separation for each wavelength, and the optical signal thus separated is set as light having one polarization direction among the light having at least two polarization directions. Multiplex optical transmission method.

According to the present invention, there are typical effects as described below.
The first effect is that the multiplexing density can be increased by utilizing the polarization characteristics of light.
The second effect is that the number of polarization axes can be changed according to the number of multiplexing by controlling the polarization.

It is a block diagram which shows the structural example of the multiplex optical transmission apparatus used as background art. It is a block diagram which shows one Embodiment of the transmitter concerning this invention. It is a block diagram which shows one Embodiment of the receiver concerning this invention. It is a figure which shows one arrangement example of arrangement | positioning of a wavelength and polarized light. 3 is a flowchart showing a multiplexed optical transmission method by the multiplexed optical transmission apparatus according to the present invention.

  Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the drawings.

  The multiplexed optical transmission apparatus according to the present invention can be configured by connecting the receiver shown in FIG. 2 and the transmitter shown in FIG. 3 through an optical transmission line such as an optical fiber. FIG. 5 is a flowchart showing a multiplexed optical transmission method by the multiplexed optical transmission apparatus according to the present invention.

  FIG. 2 is a block diagram showing an embodiment of a transmitter according to the present invention.

  As shown in FIG. 2, an optical signal (CW light) having a specific wavelength λ1 of a laser diode (LD) 11 is input to a polarizing filter (which becomes a polarizing element) 12 (step S211), and polarization characteristics in the y direction (y-polarized light). ) And is input to the optical signal modulator 13 (step S212). The optical signal input to the transmitter is converted into an electrical signal by the optical / electrical signal conversion circuit 14. This electric signal is input to the optical signal modulator 13 (step S212), and an optical modulation signal having y polarization characteristics is output to the signal multiplexing unit (multiplexer) 15 (step S213).

  Further, an optical signal (CW light) having a specific wavelength λ2 of the laser diode (LD) 111 is input to a polarizing filter (which becomes a polarizing element) 112 (step S211), and light having polarization characteristics in the x direction (X-polarized light). A signal (CW light) is converted and input to the optical signal modulator 113 (step S212). Another optical signal input to the transmitter is converted into an electrical signal by the optical / electrical signal conversion circuit 114. This electric signal is input to the optical signal modulator 113 (step S212), and an optical modulation signal having X polarization characteristics is output to the signal multiplexing unit (multiplexer) 15 (step S213).

  FIG. 3 is a block diagram showing an embodiment of a receiver according to the present invention.

  The signal transmitted from the transmitter shown in FIG. 2 and separated for each wavelength by the signal separation unit 50 (step S214) is input to the polarization controller 61, and only the signal of the desired polarization (y-polarized light) is allowed to pass ( Step S215). Thereafter, a signal of desired polarization (y polarization) is input to the coupler 64 (step S216). On the other hand, the local CW light of the specific wavelength λ1 of the laser diode (LD) 62 is also input to the polarization filter 63, and only the desired polarized light (y-polarized light) signal passes through and is input to the coupler 64 (step S216). By superimposing the signal light and the local light by the coupler 64, the optical receiver 65 performs coherent reception (step S217). This signal is input to the frame detector 66, converted into an optical signal by a subsequent optical / electrical converter 69, and output as an optical signal.

  On the other hand, the error is detected from the frame detector 66 and is detected by the error detector 67. The polarization controller 68 controls the polarization of the polarization controller 61 so that the error is minimized.

  Similarly, the signal separated at another wavelength by the signal separation unit 50 (step S214) is input to the polarization controller 161, and only the signal of the desired polarization (x-polarized light) is allowed to pass (step S215). Thereafter, a signal of desired polarization (x polarization) is input to the coupler 164 (step S216). On the other hand, the local CW light of the specific wavelength λ2 of the laser diode (LD) 162 is also input to the polarization filter 163, and only the desired polarization (x-polarized) signal passes through and is input to the coupler 164 (step S216). By superimposing the signal light and the local light by the coupler 164, the optical receiver 165 performs coherent reception (step S217). This signal is input to the frame detector 166, converted into an optical signal by the subsequent optical / electrical converter 169, and output as an optical signal.

  On the other hand, the error is transferred from the frame detector 166 to the error detector 167, and the error detector 167 detects the error. The polarization control circuit 168 controls the polarization of the polarization controller 161 so that the error is minimized.

  In this way, only signal light depending on the wavelength and polarization can be received by the transmitter.

  In the above embodiment, only x-polarized light and y-polarized light are used. However, the number of multiplexing may be increased by using polarized light finely. For simplicity, an example in which optical signals with wavelengths λ1 and λ2 are multiplexed has been described. However, a transmitter that multiplexes optical signals with a larger number of wavelengths and a receiver that separates them are configured. Of course, it may be. For example, as shown in FIG. 4, an optical signal having a wavelength of λ1 to λ6 may be multiplexed by a transmitter, and the multiplexed signal may be separated by a receiver. Further, optical signals having wavelengths of λ1 to λ6 or more may be multiplexed and the multiplexed signal may be separated by the receiver.

  Next, an example of arrangement of wavelength and polarization will be described with reference to FIG.

  In FIG. 4, the signals transmitted by the transmitter are (wavelength: polarized light) = (λ1, y polarized light), (λ3, y polarized light), (λ5, y polarized light), (λ2, x polarized light), (λ4, x (Polarized light) and (λ6, x-polarized light).

  λ1, λ3, and λ5 are y-polarized light having a wavelength interval of 50 GHz, and λ2, λ4, and λ6 are x-polarized light having a wavelength interval of 50 GHz.

  Λ1, λ2, λ3, λ4, λ5, and λ6 can be arranged at a wavelength interval of 25 GHz.

  In the case of the background art as shown in FIG. 1, even if the wavelength interval can only be 50 GHz, the density can be doubled by using polarized light.

  In the present embodiment, the signal density that can be multiplexed can be increased by performing multiplexing using wavelength polarization and polarization of light in the long-distance optical transmission apparatus.

  A part or all of the above embodiment can be described as in the following supplementary notes, but is not limited to the following configuration.

(Appendix 1)
A plurality of light sources that emit light having different wavelengths, a plurality of polarizing elements that are provided corresponding to the plurality of light sources, and that use the light from the plurality of light sources as light in at least two polarization directions; A plurality of optical signal modulators provided corresponding to the plurality of polarizing elements, to which light and information signals from the respective polarizing elements are respectively input, and optical signals from the plurality of optical signal modulators are multiplexed. An optical transmitter comprising: a signal multiplexing unit;
A signal separation unit that separates an optical signal received from the optical transmitter for each wavelength; and a light in one polarization direction among the light in the polarization directions in at least two directions among the optical signals that have been separated. An optical receiver comprising a plurality of polarization controllers that pass;
Multiplexed optical transmission apparatus having

(Appendix 2)
In the multiplexed optical transmission apparatus according to appendix 1, an error detector that detects an error in an information signal demodulated from the optical signals of the plurality of polarization controllers, and a polarization control that controls the polarization of the polarization controller so as to suppress the errors A multiple optical transmission device.

(Appendix 3)
A plurality of light sources that emit light having different wavelengths, a plurality of polarizing elements that are provided corresponding to the plurality of light sources, and that use the light from the plurality of light sources as light in at least two polarization directions; A plurality of optical signal modulators provided corresponding to the plurality of polarizing elements, to which optical signals and information signals from the respective polarizing elements are respectively input, and optical signals from the plurality of optical signal modulators are multiplexed. An optical transmitter comprising: a signal multiplexing unit;

(Appendix 4)
Receiving an optical signal polarized in at least two polarization directions and multiplexed into a plurality of wavelengths, and separating the optical signal for each wavelength; and at least the optical signal among the separated optical signals An optical receiver comprising: a plurality of polarization controllers that respectively pass light in one polarization direction out of light in two polarization directions.

(Appendix 5)
In the optical receiver according to appendix 4, an error detector that detects an error of an information signal demodulated from the optical signals of the plurality of polarization controllers, and a polarization controller that controls the polarization of the polarization controller so as to suppress the errors And an optical receiver.

(Appendix 6)
In an optical transmitter, light having different wavelengths is emitted from a plurality of light sources, the plurality of lights from the plurality of light sources are set as light in at least two polarization directions, and the polarized light and the information signal are used. Performs signal modulation, multiplexes and transmits a plurality of optical signals each modulated,
In the optical receiver, the optical signal received from the optical transmitter is subjected to signal separation for each wavelength, and the optical signal thus separated is set as light having one polarization direction among the light having at least two polarization directions. Multiplex optical transmission method.

  The present invention is used for a multiplexed optical transmission apparatus, a transmitter, a receiver, and a multiplexed optical transmission method for multiplexing and transmitting signals and separating received multiplexed signals for optical communication.

11, 111 Laser diode (LD)
DESCRIPTION OF SYMBOLS 12, 112 Polarization filter 13, 113 Optical signal modulator 14, 114 Optical / electrical signal conversion circuit 15 Signal multiplexing part 50 Signal separation part 61, 161 Polarization controller 62, 161 Laser diode (LD)
63, 163 Polarization filter 64, 164 Coupler 65, 165 Optical receiver 66, 166 Frame detector 67, 167 Error detector 68, 168 Polarization control circuit 69, 169 Optical / electrical converter

Claims (6)

A plurality of light sources that emit light having different wavelengths, a plurality of polarizing elements that are provided corresponding to the plurality of light sources, and that use the light from the plurality of light sources as light in at least two polarization directions; A plurality of optical signal modulators provided corresponding to the plurality of polarizing elements, to which light and information signals from the respective polarizing elements are respectively input, and optical signals from the plurality of optical signal modulators are multiplexed. An optical transmitter comprising: a signal multiplexing unit;
A signal separation unit that separates an optical signal received from the optical transmitter for each wavelength; and a light in one polarization direction among the light in the polarization directions in at least two directions among the optical signals that have been separated. An optical receiver comprising a plurality of polarization controllers that pass;
Multiplexed optical transmission apparatus having   2. The multiplex optical transmission apparatus according to claim 1, wherein an error detector for detecting an error of an information signal demodulated from the optical signals of the plurality of polarization controllers, and the polarization of the polarization controller to suppress the errors are controlled. And a polarization control unit.   A plurality of light sources that emit light having different wavelengths, a plurality of polarizing elements that are provided corresponding to the plurality of light sources, and that use the light from the plurality of light sources as light in at least two polarization directions; A plurality of optical signal modulators provided corresponding to the plurality of polarizing elements, to which optical signals and information signals from the respective polarizing elements are respectively input, and optical signals from the plurality of optical signal modulators are multiplexed. An optical transmitter comprising: a signal multiplexing unit;   Receiving an optical signal polarized in at least two polarization directions and multiplexed into a plurality of wavelengths, and separating the optical signal for each wavelength; and at least the optical signal among the separated optical signals An optical receiver comprising: a plurality of polarization controllers that respectively pass light in one polarization direction out of light in two polarization directions.   5. The optical receiver according to claim 4, wherein an error detector for detecting an error of an information signal demodulated from the optical signals of the plurality of polarization controllers, and the polarization of the polarization controller to suppress the errors are controlled. An optical receiver having a polarization controller. In an optical transmitter, light having different wavelengths is emitted from a plurality of light sources, the plurality of lights from the plurality of light sources are set as light in at least two polarization directions, and the polarized light and the information signal are used. Performs signal modulation, multiplexes and transmits a plurality of optical signals each modulated,
In the optical receiver, the optical signal received from the optical transmitter is subjected to signal separation for each wavelength, and the optical signal thus separated is set as light having one polarization direction among the light having at least two polarization directions. Multiplex optical transmission method.

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