Coherent polarization locking with near-perfect combining efficiency

Abstract

We demonstrate the coherent locking of two orthogonal polarized lasers by using polarization selective loss. The two orthogonal polarizations are locked coherently to produce a resultant polarization state that sees minimal cavity loss. In contrast to the Michelson locking schemes, our scheme has the advantage of easy tunability, which helps to routinely achieve near-perfect (>99%) combining efficiency even when the power of the two arms is highly imbalanced and is varied from a power ratio of unity to >5. We also demonstrate an interesting phenomenon in which a miniscule injection of an antiphase field component from one arm into another can significantly inhibit the locking mechanism.