POTENTIAL OF USING THE RADIATION FIELD OF A FABRY-PEROT PN-STRUCTURE FOR SPATIAL ROUTING IN OPTICAL CIRCUITS

Optical switching and spatial routing devices are imperative in integrated optical circuitry, often realized by electro-optic, magneto-optic, or mechanical means. In this paper, we consider the prospects for optical switches using semiconductor pnstructures in Fabry-Perot type geometry as photonic emitters. Emphasis is given to an as yet unregarded effect, which appears in the light field of a.c.- or pulse driven incoherent luminescence emitters in Fabry-Perot structure. It is shown that the light emission band on the side face of the emitter moves slightly up and down due to a ‘recombination wave' by virtue of the finite diffusion velocity of the injected excess minority carriers. As experimentally proven, the d.c.- far-field displays a ‘butterfly'- shape with a polar angle of up to 50° between wings, while a pulsed carrier injection moves lobules up and down. By the combination of such an emitter with a portioned detector element, spatial routing between detector segments is enabled. Particular emphasis is laid on a theoretical treatment of the light propagation through inhomogeneously absorbing regions inside the Fabry-Perot emitter bulk, which allows constructing the light field intensity on the side face of the Fabry-Perot body. Corresponding near-field contributions of discrete emitting layers are calculated in order to prove the proposed effect and its potential practical realization