Size dependence of transverse mode structure in oxide-confined vertical-cavity laser diodes

We analyze the transverse mode structure of selectively oxidized vertical-cavity surface-emitting semiconductor lasers as a function of the aperture size and injection current. Measurements of the spectral splittings, the near and far field sizes and the response to pulsed operation demonstrate that a parasitic thermal lens can be a dominant factor in determining the transverse resonator properties of small (<3 μm) lasers.