Efficient frequency conversion through absorptive bands of the nonlinear crystal

TL;DR

This paper presents a method for efficient frequency conversion in nonlinear crystals by using simultaneous phase-matching and adiabatic modulation, enabling high efficiency and dark intermediate states, with applications in remote frequency conversion and material studies.

Contribution

It introduces an adiabatic frequency conversion technique that maintains a dark intermediate state, improving efficiency over traditional methods.

Findings

Achieves high conversion efficiency via adiabatic modulation.

Maintains a dark intermediate frequency during conversion.

Applicable to mid-IR to visible frequency conversion.

Abstract

Two simultaneous three wave mixing processes are analyzed, where an input frequency is converted to an output frequency via an intermediate stage. By employing simultaneous phase-matching and an adiabatic modulation of the nonlinear coupling strengths, the intermediate frequency is kept dark throughout the interaction, while obtaining high conversion efficiency. This feat is accomplished in a manner analogous to population transfer in atomic stimulated Raman adiabatic passage (STIRAP). Applications include conversion between remote frequencies, e.g. mid-IR to visible, and study of electronic crystal properties in the UV absorption band.