Nonlinear MM wave generation in a planar structure containing semiconductor

Abstract

In this paper we examine the problem of EM wave generation using nonlinear mixing schemes. The structure to be analyzed is shown in Fig. 1. It consists of layers of differing dielectrics, some of which may be doped or undoped GaAs materials. It is symmetric about the center plane and is infinite and uniform in the direction transverse to the normal ○ and the direction of propagation z. In the center is a thin layer of single crystal GaAs material which exhibits optical nonlinearity. The nonlinearity consists of the contributions from both the valence electrons of the intrinsic GaAs material and the conduction electrons introduced into the medium by external means. Two optical waves propagating inside the center layer induce, as a result of optical mixing, a distribution of electric dipoles which radiate EM waves at the sum, difference or harmonic frequencies of the input waves. We are particularly interested in the generation of waves at the difference frequency which, for two CO 2 laser inputs, ranges from ∼150–4000 GHz. The dispersion characteristic and field distribution of the excited waves are determined by the waveguiding property of the whole structure at that frequency.