Abstract
The performance characteristics of 1.5-μm external cavity semiconductor lasers have been investigated. Measurements of phase, frequency, and amplitude stability are presented together with the power and threshold characteristics. Amplitude shift keyed coherent receiver sensitivity measurements gave a receiver sensitivity of -55.7 dBm at 150 Mbit/s equivalent to 137 photon/bit as compared to previous amplitude shift keying results of 520 photon/bit and the shot-noise limit of 36 photon/bit.