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

We analyze the transverse mode structure of selectively oxidized vertical-c avity surface-emitting semiconductor lasers as a function of the aperture s ize and injection current. Measurements of the spectral splittings, the nea r and far field sizes and the response to pulsed operation demonstrate that a parasitic thermal lens can be a dominant factor in determining the trans verse resonator properties of small (<3 mu m) lasers. (C) 1998 American Ins titute of Physics. [S0003-6951(98)04831-1].