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

An efficient broadband sum-frequency generation (SFG) technique using the two cascaded optical parametric processes omega(3) = omega(1) + omega(2) and omega(4) = omega(1) + 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 omega(3) and then for omega(4) SFG processes then the energy is converted adiabatically to the omega(4) field. Efficient SFG of the omega(4) field is also possible by the opposite direction of the local modulation sweep; then transient SFG of the omega(3) field is strongly reduced. Most of these features remain valid in the nonlinear regime of depleted pump.