Polarization-maintaining optical isolator

The application discloses an optical isolator having an input and an output, the optical isolator comprising a phase retardation plate positioned at the input, and an optical rotator positioned between the phase-retardation plate and the output, the isolator comprising a Faraday rotator positioned between a first polarizer and a second polarizer. The application also discloses a process comprising rotating a polarization of an optical signal using a phase retardation plate, and following the rotation of the polarization of the optical signal using a phase retardation plate, further rotating the polarization of the optical signal using an optical rotator.