Analysis of crosstalk in optical couplers and associated vulnerabilities

As a result of the huge potential bandwidth of optical fibers, optical networks have been established as the enabling technology for long-haul high-speed backbone networks based on Wavelength Division Multiplexing (WDM). Considering physical-layer impairments and vulnerabilities associated with optical components is of utmost importance to ensure successful network operation. Optical couplers, the building blocks of key network components such as multiplexers, demultiplexers and optical cross-connects, are prone to signal leaking and suffer from significant levels of crosstalk. This makes it possible for components of signals routed on different wavelengths to leak into unintended outputs and interfere with each other. Hence, the ratio between the wanted signal and unwanted interference at the output is deteriorated. In this paper, we analyze the effects of crosstalk in optical couplers and at the components, as well as methods which can enable malicious users to exploit the associated vulnerabilities to cause service degradation or eavesdropping.