Abstract

In recent years considerable research has gone into the study of all-optical switching devices in waveguides, where the requirements for a material with a large n₂ (nonlinear refractive index) may be relaxed by taking advantage of relatively high power densities and long interaction lengths.¹ This is particularly true of glass which, while having a relatively small n₂, can be conveniently drawn into optical fibers. Already a number of all-optical switching schemes have been demonstrated in silica fibers.^2,3 One possibility to reduce switching powers is to use lead glasses,⁴ which are known to have an n₂ an order of magnitude higher than fused silica. We show here that two-photon absorption (TPA) can place a fundamental restriction on such an approach.

© 1989 Optical Society of America