Non-linear periodic structures for all-optical switching

This thesis proposes an all-optical switching technique in a nonlinear periodic (grating) structure that results from optically introducing a phase shift optically within a non-linear Bragg grating structure. The thesis examines passive frequency switching for various con figurations of nonlinear Bragg grating in which the phase shift is changed by applying a high light intensity inside the structures. Also studied are the effects of applying an optical gain to these structures. An optically switched laser structure with an all-optical set/reset operation, and dual frequency transition all-optical switching operation are attained. For the fabrication of these nonlinear periodic structures the use of a quaternary semiconductor compound, InGaAsP, is suggested. The optical nonlinearity in the semiconductor structure is introduced by free carrier generation as a result of the direct absorption of photons of energy slightly lower than the semiconductor band gap. The optical loss coefficient at that photon energy follows the Urbach rule. The optical loss coefficient is chosen so that it does not overshadow the optical function of the structure. An all-optical Flip-Flop dual-frequency operation is suggested using a semiconductor periodic structure implemented as a distributed feedback (DFB) laser.