Wideband photon counting and homodyne detection.

Homodyne detection has been proposed as a means of detecting squeezed-coherent radiation. Here the response of a balanced homodyne detector to wideband squeezed-coherent states is presented. In order to carry out the analysis the theory of wideband photo detection is reviewed and in order to determine the ultimate performance limits of photomissive detectors small terms of order delta omega/omega((o)micron) that are usually neglected, where omega((o)micron) is the optical carrier frequency and delta omega is the electronics bandwidth, have been kept. It is shown that the ultimate noise reduction that can be achieved in the noise power spectrum of a homodyne detector, detecting squeezed-coherent radiation, is a factor of two worse when photomissive detectors are used instead of power flux detectors.