Abstract

It has been known for many years that a nonlinear phase shift can be imparted on the fundamental in non-phasematched second-harmonic generation via down-conversion of the second-harmonic.¹ Since two second-order processes occur in succession, this effect is known as cascading. It has recently been shown theoretically that such cascaded phase shifts could prove useful for low power all-optical switching in waveguides at watt power levels, providing that phase shifts of ir or more can be obtained.² This would allow a totally new approach to obtaining the nonlinear phase shifts needed for all-optical switching. The first measurements of cascaded phase shifts in KTP quasi-phasematched channel waveguides near 855 nm were published recently,³ and results have now been obtained in the important 1.5 pm communications window. The phase shifts obtained are large (>ir) and thus potentially useful in photonic switching applications.

© 1994 Optical Society of America