Signal-Induced Noise in Fiber Links

Abstract

Common sources of noise in fiber-optic links include intrinsic intensity noise in the laser diode output arising from the discrete nature of electrons and photons (commonly known as “RIN”, Relative Intensity Noise, and noises associated with the optical receiver. The latter, being relatively straightforward for an analog transmission system, at least in principle, is briefly reviewed in Appendix B. This chapter is concerned with a quantitative evaluation of yet another source of noise in subcarrier fiber transmission systems, namely, “signal-induced noise,” (which only exists in the presence and in the spectral vicinity of a subcarrier signal). Specifically, one considers high-frequency analog, single-mode fiber-optic links using directly modulated multimode (Fabry–Perot) and single-frequency (DFB) lasers.