Interstripe coupling and current spreading in a subthreshold double heterostructure twin stripe laser

Abstract

TWin stripe laser structures show great promise in integrated optics Systems. It has been proposed that optical interactions in such Structures should produce properties such as beam steering, optical pulse generation and bistability. However, fundamental properties of these devices, including the effect of the resistive p-type cladding layer on the current density distribution injected into the active region, the terminal behavior of the device, and the effect of the stripe width and spacing current density distributions have not yet been considered. This paper considers the current density distribution problem of a twin stripe laser, and examines the effect on the distribution of current injection into both stripes, interstripe coupling via the resistance of the p-type cladding layer and the geometric factors of cladding layer thickness, electrode width and spacing. A diode model is assumed for the heterostructure, and finite difference techniques are used to calculate the 2 D potential distribution in the p-type cladding layer and the current density distribution in the active layer. Numerical and experimental results highlight the effect of the nonlinear diode boundary on the current density distribution and show the changes in the current distribution which occur for relatively small fluctuations in current injected into the stripes and equally small changes in the geometry.