Polarization control in a photonic integrated circuit

Abstract

The present invention provides a system, apparatus and method to maintain the polarization state of an optical signal propagating within a photonic integrated circuit, or from a first photonic integrated circuit to a second photonic integrated circuit. According to various embodiments of the invention, an optical circuit is provided which includes an optical coupler configured to accept a first optical signal on a first input and a second optical signal on a second input, the second optical signal having a polarization state. The optical coupler may combine the first and second optical signals into an optical output signal. A principle axis of a first end of an optical fiber is may be configured to align with the polarization state of the second optical signal, such that a polarization maintaining connection is established. The polarization state may be a TM polarization state, a TE polarization state, or another polarization state. The optical circuit may include birefringent structures, such as birefringent waveguides and birefringent wavelength selective couplers, to further maintain the polarization of optical signals propagating through the photonic integrated circuits.