Chapter 11 - Optical performance monitoring based on nonlinear optical techniques

Abstract

Nonlinear optics provides a toolbox of diagnostic measurements with potential for use in optical performance monitoring (OPM) applications. Advanced functionality combined with wide bandwidth and almost unlimited bit rate scalability is the primary advantage of nonlinear approaches. In some cases, the ability to directly manipulate the optical signal provides capabilities or performance not achievable using electronic processing following photodetection. Targeting OPM opportunities in which electronic processing falls short is a promising route to commercialization. Often, however, OPM applications require simple, low-cost solutions and the higher performance is not required. On the other hand, test and measurement applications tend to place more of a premium on performance and need to handle lab signals not found in deployed systems. As a result, nonlinear optics can be expected to continue to find value in the laboratory, particularly as bit rates and the complexity of optical transmission systems increase. Optical monitoring devices have historically found utility in the test lab before being embraced in systems. For example, optical spectrometers were widely used in labs and for system maintenance, but were only recently deployed in systems. Greater use of photonic integration likely will lead to new applications for nonlinear optics. In electronics, monitoring is frequently implemented with little additional processing or cost. A similar argument can be made in the case of using nonlinear optics with other photonic integrated chip devices because additional packaging may not be required and many of the photonic components may be readily available on chips. While the role of nonlinear optics in OPM applications is still unclear, the promise due to the capabilities that are offered and the increased potential due to advances in transmission functionality and capacity remain strong.