Patent ID: 7280770
Filing Date: 2007-10-09
Classification: H04B

Abstract:
1. A receiver, comprising: a polarization-maintaining waveguide optical coupler for combining an input signal and a linearly-polarized local oscillator signal into a first combined signal, said optical coupler having a coupler birefringent axis and comprising a first end surface and a second end surface, said second end surface opposite said first end surface; a polarization filter attached to said first end surface of said optical coupler for filtering a local oscillator signal having an arbitrary polarization to form said linearly-polarized local oscillator signal with a polarization direction parallel to said coupler birefringent axis; a polarization-dependent beam splitter having a walk-off axis direction, and attached to said second end surface of said optical coupler with said walk-off axis direction at an angle greater than zero and less than ninety degrees with respect to said coupler birefringent axis, said polarization-dependent beam splitter for generating first and second component signals from said first combined signal, said first component signal having a polarization that is orthogonal to said second component signal, said first component signal being spatially displaced from said second component signal; a first detector for converting said first component signal into a first electrical signal; and a second detector for converting said second component signal into a second electrical signal.