Optimization of adiabatic frequency conversion in an all-pass resonator

Adiabatic frequency conversion (AFC) is a promising alternative for shifting the frequency of optical signals. In this paper we present a comprehensive theoretical study of the energy efficiency of AFC in an all-pass resonator. Through the Cauchy-Schwarz inequality, we deduce the upper limit of the energy efficiency of the AFC process and analyze its dependence on the input pulse shape. For a fixed pulse shape, we discuss the dependence of the AFC efficiency on its relevant timescales. We show that maximum efficiency requires overcoupling of the resonator to a degree dependent on the input pulse duration. We compare and contrast the requirements for optimal AFC for pulsed and continuous-wave inputs.