A polarization diversity receiver system for yielding multiple heterodyne optical output signals from an incident optical beam having a p-polarized component and an s-polarized component comprises first and second sequentially-arrayed polarizing beamsplitters, and three photodetectors, eac h of which receives a heterodyne optical signal. The polarization diversity receiver system tracks the largest of these three signals, and uses only thi s largest one for subsequent signal processing. There is a minimum for this largest signal that is dependent on the input polarizations of the two optic al fields whose beat note is the heterodyne signal. Thus, the object is to maximize the minimum of this largest of the three heterodyne signals. The first polarizing beamsplitter ideally splits the incident beam into a transm itted beam portion including approximately 100% of the p-polarized component and approximately 33% of the s-polarized component, and a reflected beam portion including approximately 0% of the p-polarized component and approximately 67% of the s-polarized component. The reflected beam portion exits from the first polarizing beamsplitter as a first heterodyne optical o utput signal, and impinges on a first photodetector. The transmitted beam portion exits from the first beamsplitter, and then undergoes an effective 45O rotat ion of its polarization eigenstates around its axis of propagation, either prior to or during its passage through the second polarizing beamsplitter. The second beamsplitter splits the rotated transmitted beam portion into second and thi rd heterodyne optical output signals, which respectively impinge upon second an d third photodetectors.
HIGH EFFICIENCY POLARIZATION DIVERSITY RECEIVER SYSTEM