Optical wavelength division multiplex signal monitoring apparatus

An optical wavelength division multiplexed signal monitoring apparatus comprising:

• optical wavelength division demultiplexing means for carrying out optical wavelength division demultiplexing of an optical wavelength division multiplexed signal including N optical signals with a bit rate f0 (bits/s), which are wavelength multiplexed, where N is an integer greater than one;
• sampling clock generating means for generating a sampling clock signal whose repetition frequency is f1 (Hz) (f1=(n/m)f0+a, where n and m are a natural number, and a is an offset frequency);
• one or N optical gating means for sampling intensities of the optical wavelength division multiplexed signal or the optical wavelength division demultiplexed signals by using the sampling clock signal generated by said sampling clock generating means;
• one or N opto-electric conversion means for receiving optical signals output by said optical gating means, and for converting the optical signals into said electric intensity modulated signals;
• and
• electric signal processing means for carrying out optical signal quality evaluation based on the electric intensity modulated signals output from said one or N opto-electric conversion means,
• wherein said electric signal processing means is a single system, and obtains optical signal intensity distribution from the electric intensity modulated signals output by said one or N opto-electric conversion means, and evaluates an optical signal quality parameter based on the optical signal intensity distribution.

An optical wavelength division multiplexed signal monitoring apparatus comprising:

• optical wavelength division demultiplexing means for carrying out optical wavelength division demultiplexing of an optical wavelength division multiplexed signal including N optical signals with a bit rate f0 (bits/s), which are wavelength multiplexed, where N is an integer greater than one;
• optical sampling pulse train generating means for generating an optical sampling pulse train whose repetition frequency is f1 (Hz) (f1=(n/m)f0+a, where n and m are a natural number, and a is an offset frequency) and whose pulse width is sufficiently narrower than a time slot of the optical signal with the bit rate f0 (bits/s);
• one or N combination of optical combining means and nonlinear optical media, the optical combining means for combining the optical wavelength division multiplexed signal or the optical wavelength division demultiplexed signal with the optical sampling pulse train, and the nonlinear optical media for inducing nonlinear interaction between the optical sampling pulse train and the optical wavelength division multiplexed signal or the optical wavelength division demultiplexed singal combined by said optical combining means;
• one or N opto-electric conversion means for receiving the cross-correlation optical signals generated by the nonlinear interaction in said nonlinear optical media, and for converting the cross-correlation optical signals into electric intensity modulated signals;
• and
• electric signal processing means for carrying out optical signal quality evaluation based on the electric intensity modulated signals output from said one or N opto-electric conversion means,
• wherein said electric signal processing means is a single system, and obtains optical signal intensity distribution from the electric intensity modulated signals output by said one or N opto-electric conversion means, and evaluates an optical signal quality parameter based on the optical signal intensity distribution.