Carrier-to-noise ration performance of a ninety-channel FM video optical system employing subcarrier multiplexing and two cascaded traveling-wave laser amplifiers

Abstract

Distribution of multichannel video signals in the subscriber loop by subcarrier multiplexing (SCM)1 has gained increased attention recently, principally because SCM systems have attractive near-term economics. However, due to the low sensitivity of a 50-Ω receiver (−20 to −13 dBm) and limited laser launch power into single-mode fiber (≈ 0 dBm), the power budget of an SCM system is generally inadequate for point-to-multipoint distribution. This limitation can be overcome by employing traveling-wave (TW) laser amplifiers, because their wide bandwidth (40-50 nm) can accommodate all the modes of a multilongitudinal-mode laser, and they have high saturation output power (0-5 dBm). We present both experimental and analytical results of the carrier-to-noise ratio (CNR) performance of an SCM system which carries ninety FM video signals by using a high-speed GaInAsP laser and two cascaded TW amplifiers.