On the performance of optical phase-shift-keying with preamplify-feedforward-homodyne reception (comment and reply)

Recently K. Kikuchi (ibid., vol.4, p.195-7, 1992) proposed preamplify-feedforward-homodyne detection as a technique for realizing subshot-noise sensitivity in binary phase-shift keyed optical communication. It is demonstrated that this system does not yield subshot-noise performance in small-angle analog phase modulation, and it offers no error-probability reduction in binary phase-shift keying. In both cases, preamplify-feedforward-homodyne detection requires twice as many signal-beam photons as ordinary homodyne detection to achieve the same communication performance. K. Kikuchi responds to this letter and another letter challenging the bit-error-rate performance of the receiver he proposed (ibid., vol.4, p.195-7, Feb. 1992) and defends his results.<
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