All-Optical Quasi-Phase Matching of Frequency Doubling Using Counterpropagating Light

Nonlinear optical frequency conversion is a useful method for creating coherent light sources with unique capabilities. ~The main challenge for conversion efficiency of processes like frequency doubling is the chromatic dispersion of the nonlinear medium. ~Successful techniques for correcting the phase mismatch between the different frequencies are often limited by the type of nonlinear medium that may be used. ~An all-optical method of quasi-phase matching using counterpropagating light has recently been demonstrated for high-order harmonic generation, an extreme nonlinear process. ~Sequences of counterpropagating pulses are used to interfere with the harmonic generation process periodically, correcting the phase mismatch and boosting efficiency. ~We report progress on an experimental investigation of the effect of counterpropagating light on the more commonly used low-order nonlinear optical processes. ~We present data showing the effects of a single counterpropagating pulse on the efficiency of frequency doubling of a Ti:sapphire ultrafast laser oscillator in beta-Barium Borate.