JP4692536B2 - Wavelength detection method - Google Patents

Description

  The present invention relates to a method for detecting the number of wavelengths input to a communication device in an optical wavelength division multiplexing communication system.

  In a conventional optical wavelength division multiplexing communication system, an input optical signal is photoelectrically / electrically converted by a photoelectric conversion element in order to detect the number of input wavelengths to a communication device constituting the system, and the current value or voltage value thereof is converted. On the other hand, by setting a fixed threshold value, the absolute value of the presence or absence of the wavelength is determined by comparing the two.

  In addition, as a countermeasure against loss fluctuation when a problem occurs in a transmission path for transmitting multiplexed optical signals, a method of setting a fixed threshold value to be set to a very low value has been adopted.

JP 2002-314486 A

  The input wavelength detection method in the conventional optical wavelength division multiplexing communication system performs wavelength presence / absence determination with a very low threshold value as a countermeasure against loss variation of the optical transmission line as described above. When the input light intensity is detected, the input interruption cannot be detected until the input light intensity drops to a very low value, and the device control corresponding to the input interruption is delayed. In addition, when detecting an input of a certain wavelength, the wavelength of the input light is detected with a very low value, so that the input of the wavelength is detected even though the light intensity is insufficient. It had an effect on communication.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to obtain a wavelength detection method that can increase the threshold and reliably detect the presence or absence of a wavelength.

The wavelength detection method in the present invention includes a coupler that branches an optical signal from a transmission line that transmits the multiplexed optical signal, a wavelength demultiplexer that splits the optical signal branched by the coupler for each wavelength, A plurality of photoelectric conversion elements that are provided for each wavelength of the signal and that convert the optical signal of each wavelength demultiplexed by the wavelength demultiplexer into an electrical signal corresponding to the light intensity, and output each of the plurality of photoelectric conversion elements the output and is compared with a predetermined threshold value with a wavelength existence determination circuit to determine the presence or absence of the optical signal of each wavelength, threshold wavelength existence determination circuit, based on the maximum value of the output of said plurality of photoelectric conversion elements It is constituted so that it is a value.

  According to the present invention, the threshold set in the wavelength presence / absence determination circuit is set to a value based on the maximum value of the output of the photoelectric conversion element. is there.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. An embodiment of an optical wavelength division multiplexing communication apparatus in an optical wavelength division multiplexing communication system according to the present invention is shown in FIG.

  That is, the optical signal is branched by the coupler 2 provided in the optical transmission line 1 for transmitting the wavelength-multiplexed optical signal, and is input to the wavelength demultiplexer 3. The wavelength demultiplexer 3 demultiplexes the input optical signal for each wavelength and inputs the demultiplexed optical signals to the photoelectric conversion elements 4 provided for each wavelength. Each photoelectric conversion element 4 converts the input optical signal having a predetermined wavelength into an electrical signal corresponding to the light intensity, and inputs it to the wavelength presence / absence determination circuit 5.

  The wavelength presence / absence determination circuit 5 determines the number of optical wavelengths input to the optical wavelength division multiplexing apparatus by comparing the level of the electrical signal input from each photoelectric conversion element 4 with a desired threshold value.

  Hereinafter, the determination operation of the wavelength presence / absence determination circuit 5 will be described with reference to FIGS.

  That is, the electrical signal converted by the photoelectric conversion element 4 is compared in the wavelength presence / absence determination circuit 5, and a relative threshold is set with reference to the input light intensity of a wavelength that satisfies a certain condition. Specifically, as shown in FIG. 2, the relative threshold (Threshold) is set with the largest value among the electric signals corresponding to the six wavelengths as a reference. If the input light intensity is equal to or greater than this relative threshold, it is determined that there is a wavelength, and if it is equal to or less than this relative threshold, it is determined that there is no wavelength. In FIG. 2, there is no loss fluctuation in the optical transmission line 1, the light intensity at all wavelengths is large, and the relative threshold value is also large. On the other hand, even if there is some loss fluctuation in the optical transmission line as shown in FIG. 3, the presence or absence of the wavelength can be determined by setting a relatively low relative threshold (Threshold).

  Next, in the above embodiment, the relative threshold value based on the maximum optical signal input by the optical wavelength multiplexing communication apparatus is set in the wavelength presence / absence determination circuit 5, but the relative threshold value based on the average value is set. It may be a thing.

  That is, as shown in FIG. 4, the relative threshold (Threshold) is set with reference to the average value of the electrical signals corresponding to the six wavelengths. If the input light intensity is equal to or greater than this relative threshold, it is determined that there is a wavelength, and if it is equal to or less than this relative threshold, it is determined that there is no wavelength. In FIG. 4, there is no loss fluctuation in the optical transmission line 1, the light intensity at all wavelengths is large, and the relative threshold value is also large. On the other hand, even if there is some loss fluctuation in the optical transmission line as shown in FIG. 5, the presence or absence of the wavelength can be determined by setting a slightly lower relative threshold (Threshold).

  Therefore, the wavelength detection method according to the embodiment of the present invention has an effect that the threshold value can be increased, the word number of the input wavelengths is not detected, and the presence / absence of the wavelength can be reliably detected.

  The present invention can be applied to an apparatus that detects the number of input wavelengths input to an optical wavelength division multiplexing communication apparatus in an optical wavelength division multiplexing communication system.

It is a figure which shows the structure of the optical wavelength division multiplexing apparatus which concerns on embodiment of this invention. It is the figure which showed the relative threshold value setting system by embodiment of this invention. It is the figure which showed the change of the relative threshold when loss fluctuation | variation generate | occur | produces in embodiment of this invention. It is the figure which showed the relative threshold value setting system by another embodiment of this invention. It is the figure which showed the change of the relative threshold when the loss fluctuation | variation generate | occur | produces in another embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Optical transmission line 2 Coupler 3 Wavelength demultiplexer 4 Photoelectric conversion element 5 Wavelength presence determination circuit

Claims (1)

A coupler that branches the optical signal from a transmission path that transmits the multiplexed optical signal, a wavelength demultiplexer that splits the optical signal branched by the coupler for each wavelength, and is provided for each wavelength of the optical signal, A plurality of photoelectric conversion elements that convert and output an optical signal of each wavelength demultiplexed by the wavelength demultiplexer into an electrical signal corresponding to the light intensity, and outputs and a predetermined threshold value of each of the plurality of photoelectric conversion elements characterized by comprising a wavelength presence judgment circuit compared to determine the presence or absence of the optical signal of each wavelength, threshold wavelength existence determination circuit is a value relative to the maximum value of the output of said plurality of photoelectric conversion elements Wavelength detection method.

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