Large-area single-mode VCSELs and the self-aligned surface relief

摘要

The effect of mode-profile specific etching of the top layer innselectively oxidized vertical-cavity surface-emitting laser (VCSEL)nstructures at 850-nm emission wavelength is examined. For highnreproducibility, a self-aligned etching technique is demonstrated whichnaligns surface etch and oxide aperture by only one additionalnphotoresist step. By optimizing layer structure and etch spot size,ncompletely single-mode devices with aperture diameters up to 16 Μmnare obtained. Maximum single-fundamental-mode output power of 3.4 mW atnroom temperature and over 1 mW at 0°C is obtained with a maximumnfar-field angle of 5.5°. Using parameters for etch spot height andndiameter, Gaussian beam spot size and phase curvature, the measuredndiffracted far-field distribution is fitted well over a 20-dB intensitynrange. The chosen fit parameters therefore enable one to estimate thenamount of phase curvature within the VCSEL for different operationncurrents, which cannot be obtained with available measurement methods