This paper analyzes the amplification of optical single-sideband signals, highlighting the significance of the optical signal bandwidth in determining signal-amplified spontaneous emission (ASE) beat noise. It predicts that an electrical noise figure of one may be realized for single-sideband signals using appropriate optical filtering. It verifies noise figure reduction experimentally, demonstrating an electrical noise figure of 1.1 the spontaneous emission factor of the amplifier, which is 2.6 dB below the limit for conventional intensity-modulated signals.
Robert A. Griffin, P. M. Lane, and J. J. O'Reilly, "Optical Amplifier Noise Figure Reduction for Optical Single-Sideband Signals," J. Lightwave Technol. 17, 1793- (1999)