Showing papers by "Jeffrey H. Shapiro published in 1980"

Optical communication with two-photon coherent states--Part III: Quantum measurements realizable with photoemissive detectors

Abstract: In Part I of this three-part study it was shown that the use of two-photon coherent state (TCS) radiation may yield siginificant performance gains in free-space optical communicatinn if the receiver makes a quantum measurement of a single field quadrature In Part II it was shown that homodyne detection achieves the same signal-to-noise ratio as the quantum field quadrature measurement, thus providing a receiver which realizes the linear modulation TCS performance gain found in Part I Furthermore, it was shown in Part il that ff homodyne detection does exactly correspond to the field quadrature measurement, then a large binary communication performance gain is afforded by homodyne detection of antipodal TCS signals The full equivalence of honmdyne detection and single-quadrature field measurement, as well as that of heterodyne detection and two-quadrature field measurement, is established Furthermore, a heterodyne configuration which uses a TCS image-band oscillator in addition to the usual coherent state local oscillator is studied This coafiguration termed TCS heterodyne detection is shown to realize all the quantum measurements described by arbitrary TCS The foregoing results are obtained by means of a representation theorem which shows that photoemissive detection realizes the photon flux density measurement

Optical waveguide tap with infinitesimal insertion loss.

Abstract: The novel fluctuation characteristics predicted for two-photon coherent-state radiation make possible high signal-to-noise ratio detection from a directional coupler that is very weakly linked to an information-bearing optical waveguide.