Broadband sum-frequency generation using cascaded processes via chirped quasi-phase-matching

Abstract

An efficient broadband sum-frequency generation (SFG) technique using the two cascaded optical parametric processes ${\ensuremath{\omega}}_{3}={\ensuremath{\omega}}_{1}+{\ensuremath{\omega}}_{2}$ and ${\ensuremath{\omega}}_{4}={\ensuremath{\omega}}_{1}+{\ensuremath{\omega}}_{3}$ is proposed. The technique uses chirped quasi-phase-matched gratings, which, in the undepleted pump approximation, make SFG analogous to adiabatic population transfer in three-state systems with crossing energies in quantum physics. If the local modulation period first makes the phase match occur for ${\ensuremath{\omega}}_{3}$ and then for ${\ensuremath{\omega}}_{4}$ SFG processes then the energy is converted adiabatically to the ${\ensuremath{\omega}}_{4}$ field. Efficient SFG of the ${\ensuremath{\omega}}_{4}$ field is also possible by the opposite direction of the local modulation sweep; then transient SFG of the ${\ensuremath{\omega}}_{3}$ field is strongly reduced. Most of these features remain valid in the nonlinear regime of depleted pump.