Abstract

Direct frequency modulation of a distributed-feedback (DFB) semiconductor laser is an attractive technique because it can obtain high modulation depths with low drive powers. For direct-detection systems an optical frequency, discriminator must precede the photodetector. Systems that use optical filters as frequency discriminators are also well suited for wavelength- division-multiplexing (WDM) applications with optical amplifiers.^1,2 Then, the optical filter also reduces the amplified-sponta- neous-emission (ASE) noise and provides wavelength selectivity. In this paper we report the use of a tunable fiber Fabry-Perot (FFP) interferometer as an optical frequency discriminator for a 10-channel FSK-SCM system in the frequency range 2.1-3.9 GHz. We have developed, to our knowledge, the first comprehensive models of the FFP response to an optical FM signal that accurately predict the optimal system parameters and performance.

© 1993 Optical Society of America