Optical performance monitoring techniques based on pilot tones for WDM network applications

Abstract

Feature Issue on Optical Performance Monitoring (OPM). We report on the pilot-tone-based optical performance monitoring techniques for use in the wavelength-division multiplexing (WDM) network. We first described the operating principle of the pilot-tone-based monitoring technique and estimated its scalability by analyzing potential problems. We then reviewed the techniques proposed for monitoring various optical parameters of WDM signals--such as optical power, wavelength, optical path, and cross talk--using pilot tones. We also presented examples of various network elements using the pilot-tone-based monitoring technique. In addition, we reviewed the pilot-tone-based monitoring techniques used in adaptive compensators for chromatic dispersion and polarization-mode dispersion, and we discussed their limitations and possible solutions. For example, we demonstrated a simple technique for monitoring the chromatic dispersion and polarization-mode dispersion simultaneously, without their affecting each other, by scrambling the state of polarization of the optical signal.