Broadband sum frequency generation via chirped quasi-phase-matching

An efficient broadband sum frequency generation (SFG) technique using the two collinear optical parametric processes ω3=ω1+ω2 and ω4=ω1+ω3 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 %for aperiodically poled quasi-phase-matching first makes the phase match occur for ω3 and then for ω4 SFG processes then the energy is converted adiabatically to the ω4 field. Efficient SFG of the ω4 field is also possible by the opposite direction of the local modulation sweep; then transient SFG of the ω3 field is strongly reduced. Most of these features remain valid in the nonlinear regime of depleted pump.