Abstract

Light that is fed back into a laser, so-called self-mixing interference (SMI), can have detrimental effects when the laser is used in optical communications [1]. On the other hand SMI can also be used to measure distance, velocity and displacements [2]. SMI changes the conditions for the threshold gain and phase and thus alter threshold current, differential quantum efficiency, laser power and wavelength. We have recently experimentally demonstrated SMI in a standard, commercially available, single-mode VCSEL as a means for measuring very small deflections of micrometer-sized cantilevers [3] (Fig. la). Here, we have numerically investigated SMI in an oxide aperture VCSEL to optimize the epitaxial structure for higher performance. The standard investigated structure is emitting light at 970 nm from 3 In_0.17Ga_0.83As/GaAsP QWs sandwiched between 36 pairs of bottom mirror and 23 pairs of top mirror (Al_xGa_1-xAs). The mirrors are doped with N_p = 2.5*10¹⁸ and N_n = 2.0*10¹⁸ and doping loss is accounted for when calculating the reflectivity.

© 2009 IEEE