Efficient broadband frequency generation in composite crystals

By using ideas from the technique of composite pulses in quantum physics we propose a highly efficient and broadband technique for sum and difference frequency generation with composite nonlinear crystals. The proposed technique works both with continuous-wave and pulsed lasers, as well as in the linear and nonlinear regimes of depleted and undepleted pumps, respectively. The feasibility of the technique is supported by numerical simulations for a composite Potassium Titanium Oxide Phosphate crystal.