Efficient broadband sum and difference frequency generation with a single chirped quasi-phase-matching crystal

TL;DR

This paper introduces a broadband frequency generation method using chirped quasi-phase-matching crystals that enables efficient and switchable sum and difference frequency generation through adiabatic population transfer.

Contribution

It presents a novel technique leveraging chirped gratings for broadband, switchable sum and difference frequency generation in a single crystal, inspired by quantum adiabatic transfer principles.

Findings

Achieves efficient broadband frequency conversion

Enables switching between sum and difference frequencies

Demonstrates adiabatic transfer analogous to quantum systems

Abstract

We propose an efficient broadband frequency generation technique for two collinear optical parametric processes $\omega_3=\omega_1+\omega_2$ and $\omega_4=\omega_1-\omega_2$. It exploits chirped quasi-phase-matched gratings, which in the undepleted pump approximation regime perform population transfer that is analogous to adiabatic population transfer in a three-state ``vee'' quantum system. The energy of the input fields is transferred adiabatically either into $\omega_3$ or $\omega_4$ field, depending on which of the two phase matchings occurs first by the local modulation period in the crystal. One can switch the output between $\omega_3$ and $\omega_4$ by inverting the direction of the local modulation sweep, which corresponds to a rotation of the crystal by angle $\pi$