Technology for flexibly monitoring optical signal quality in transparent optical communications [Invited

Abstract

Feature Issue on Transmission in Optically Transparent Core NetworksThis is a review of our previous work about an optical signal quality monitoring method that uses asynchronous sampling, which is a sampling technique that does not use timing extraction. The use of high-speed asynchronous sampling and the adjustment of the sampling rate enable simple open eye-diagram monitoring and the evaluation of a fixed-timing Q factor (Qt) at the maximum eye-opening timing phase. This method was experimentally verified using an optical signal quality monitoring circuit. We obtained a good relationship between the measured Qt and Q [which is the Q factor calculated from the bit error rate (BER)], indicating that the BER was estimated by the measured Qt with good accuracy. Moreover, as an easier method, we also introduce an averaged Q factor (Qavg) evaluation method, which measures the Qavg value from an asynchronous eye diagram (timing drifted eye diagram). Standardization of our optical signal quality monitoring technology is in progress in the IEC (International Electrotechnical Commission).