Analysis of asymmetric, nonlinear, planar AlGaAs/GaAs multiple quantum-well directional couplers

Abstract

We present an analysis of a Kerr-type, nonlinear, all-optically controlled asymmetric planar directional coupler. One guiding layer of the asymmetric directional coupler is a linear AlGaAs medium, and the other guiding layer contains an AlGaAs/GaAs multiplequantum-well, Kerr-like nonlinear medium. The coupling of this device is studied analytically assuming no losses. Jacobian elliptic functions are introduced to solve the nonlinear wave equations in the nonlinear medium. The coupling length is determined by the superposition of the perturbed symmetric-like and perturbed antisymmetric-like solutions. Propagation constants of these two perturbed solutions can be determined from the dispersion equation. The coupling length and the intensity distributions of these couplers are analyzed as a function of the material composition and structure and the waveguiding geometry. Comparisons are made between the nonlinear symmetric and asymmetric directional couplers. Potential applications of asymmetric directional couplers for optical threshold switching and for optical signal processing will be discussed.