FDMA-FSK 1 Gb/s Star Network Using LD-Pumped Erbium-Doped Fiber Preamplifiers with Optimal Noise Filtering

A key advantage of a frequency-division-multiple-access (FDMA) optical star network is high-speed simultaneous distribution of information to many users. An attractive implementation [1,2] is to frequency-shift-key (FSK) modulate N laser transmitters (Tx) and use direct-detection receivers (Rx), each consisting of a fiber Fabry-Perot [3] demodulator/demultiplexer. One disadvantage of this simple scheme is the limitation placed on the number of network users due to the inherent (1/N) power splitting losses of the N×N star coupler. These splitting losses as well as substantial component insertion losses can be compensated for by including an Erbium-doped fiber amplifier (EDFA) [4-6] in each receiver [1]. Such amplifiers have the advantages of being compatible with a fiber-based system, providing high gain and output saturation power, and being insensitive to polarization and crosstalk effects.