Characterization of Complex Optical Modulation Formats at 100 Gb/s and Beyond by Coherent Optical Sampling

Optical fiber communication systems are migrating toward the use of sophisticated, nonbinary, modulation formats. It is thus important to develop measurement techniques and solutions capable of unambiguously quantifying such signals and associated hardware. Although one can adapt certain techniques developed for wireless signal characterization, significant differences exist between optical and RF wireless implementations of advanced modulation formats. To meet this measurement demand we present a method for characterizing high symbol rate multilevel modulation optical signals with high fidelity, based on coherent optical sampling, as a complement to the standard real-time electrical sampling approach. The technique enables constellation-and waveform monitoring, bit-error rate and error-vector magnitude analysis, which makes it suitable for transmitter characterization

Simultaneous waveform and bit-error-rate measurements of 66 GBd PDM-16-QAM signals

We demonstrate waveform analysis and BER measurements of a PDM-NRZ-16-QAM signal at a record base symbol rate using asynchronous optical under-sampling. A BER below the FEC limit was achieved at 528 Gbit/s

Time-resolved error vector magnitude for transmitter mask testing in coherent optical transmission systems

We propose a novel transition-sensitive measurement approach for coherent optical systems. The time-resolved error vector magnitude (EVM), combined with mask testing, is a powerful tool for pass/fail testing of transmitters in coherent systems

Optical phase-sensitive sampling for high fidelity capture of advanced, high baud-rate optical waveforms and signals

We discuss all-optical sampling techniques to capture optical waveforms with both high fidelity and time resolution. Different approaches are possible, each with associated performance - complexity trade-offs. We cover not only sampling of intensity waveforms but also complex modulation formats such as QPSK and 16-QAM and also discuss the distinctions between real time sampling and equivalent-time sampling

Optical phase-sensitive sampling for high fidelity capture of advanced, high baud-rate optical waveforms and signals

We discuss all-optical sampling techniques to capture optical waveforms with both high fidelity and time resolution. Different approaches are possible, each with associated performance - complexity trade-offs. We cover not only sampling of intensity waveforms but also complex modulation formats such as QPSK and 16-QAM and also discuss the distinctions between real time sampling and equivalent-time sampling