Abstract

The effect of a beam splitter on the quantum EM field is central to the treatment of many quantum optics situations, and two distinct approaches may be found in the literature. In the first the beam splitter is described via its true modest In the second it is regarded as a device that couples light modes. A unitary operator that transforms the annihilation operator for an incident mode into a linear combination of such operators for transmitted and reflected modes is introduced to describe its behaviour. The first approach is readily obtained by applying the true mode theory³ of macroscopic canonical quantization. It is shown in this paper that the second approach can be derived from the quasi-mode theory⁴.

© 1998 IEEE