Quadrature phase detector using two-mode waveguides.

We present a novel design for quadrature phase detection utilizing two-mode optical waveguides for optical interferometric systems. A pair of interferometric signals having quadrature optical phase information can be obtained from the near-field and far-field patterns of a two-mode waveguide output. The operational principle is based on a pi/2 differential phase shift between two modal beams occurring during their transition from near-field to far-field radiation patterns.