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

Abstract

We propose an efficient broadband frequency generation technique for two collinear optical parametric processes ω3=ω1+ω2 and ω4=ω1-ω2. 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 ω3 or ω4 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 ω3 and ω4 by inverting the direction of the local modulation sweep, which corresponds to a rotation of the crystal by angle π