Efficient broadband frequency conversion via shortcut to adiabaticity

TL;DR

This paper explores advanced shortcut to adiabaticity techniques to enhance broadband frequency conversion efficiency, robustness, and tunability in nonlinear optical processes, reducing crystal length and improving stability against environmental variations.

Contribution

It introduces a novel approach combining inverse engineering, perturbation theory, and optimal control to optimize phase mismatch and improve frequency mixing robustness.

Findings

Significant reduction in crystal length for frequency conversion.

Enhanced robustness against temperature and wavelength fluctuations.

Development of a tunable, experimentally feasible mixing scheme.

Abstract

The method of adiabatic frequency conversion, in analogy with the two level atomic system, has been put forward recently and verified experimentally to achieve robust frequency mixing processes such as sum and difference frequency generation. Here we present a comparative study of efficient frequency mixing using various techniques of shortcuts to adiabaticity (STA) such as counter-diabatic driving and invariant-based inverse engineering. We show that, it is possible to perform sum frequency generation by properly designing the poling structure of a periodically poled crystal and the coupling between the input lights and the crystal. The required crystal length for frequency conversion is significantly decreases beyond the adiabatic limit. Our approach significantly improves the robustness of the process against the variation in temperature as well as the signal frequency. By introducing a single parameter control technique with constant coupling and combining with the inverse engineering, perturbation theory and optimal control, we show that the phase mismatch can be further optimized with respect to the fluctuations of input wavelength and crystal temperature that results into a novel experimentally realizable mixing scheme.