Nonlinear adiabatic optical isolator.

We theoretically propose a method for optical isolation based on adiabatic nonlinear sum frequency generation in a chirped quasi-phase-matching crystal with strong absorption at the generated sum frequency wave. The method does not suffer from the limitations of dynamic reciprocity found in other nonlinear optical isolation methods and can provide tunable optical isolation with ultrafast all-optical switching capability. Moreover, as an adiabatic technique, it is robust to variations in the optical design and is relatively broadband.