We show that cascaded second-order nonlinear-optical processes can occur in a convenient polarization-gate beam geometry. Our arrangement uses type II phase matching, and both individual second-order processes (upconversion and downconversion) are simultaneously phase matched. This geometry can be applied to efficient ultrafast optical switching. With a β-barium borate crystal and lightly focused 250-fs, 7.3-µJ pulses, we achieve a switching efficiency of 15% and an on–off ratio of 3 × 104 on a pulse-length-limited time scale.
© 1997 Optical Society of America
Marco A. Krumbügel, John N. Sweetser, David N. Fittinghoff, Kenneth W. DeLong, and Rick Trebino, "Ultrafast optical switching by use of fully phase-matched cascaded second-order nonlinearities in a polarization-gate geometry," Opt. Lett. 22, 245-247 (1997)