Coherent optical waveguide transmission systems are expected to offer improved system performance. Spurious optical radiation outside the signal band can be eliminated homodyning or heterodyning techniques and improvements on the order of 10 - 30 dB 1,2 can be realized depending upon the detection scheme utilized. Polarization mode dispersion (PMD) and cross-coupling between modes may result in waveguide bandwidth-length products that are impractical for coherent telecommunication systems. It is important to determine the measurements and conditions of measurement required to ensure waveguide compatibility with coherent transmission systems.
Anne B. Bussard,
"Measurement Requirements for Coherent Optical Waveguide Communication", Proc. SPIE 0568, Coherent Technology in Fiber Optic Systems I, (31 October 1985); doi: 10.1117/12.949854; https://doi.org/10.1117/12.949854