Vertical-cavity surface-emitting lasers with low-ripple optical pumping windows

A general technique for numerically optimizing the optical admittances in GaAs QW vertical-cavity laser structures is used to suppress the interference ripple in the typical reflectance/transmittance spectra. This technique is applicable to any vertical-cavity device whose photonic properties at various wavelengths requires modification for specific applications. In this paper, we report the use of this optimization method to enhance the coupling of pump light into 850-nm vertical-cavity surface-emitting lasers (VCSELs). We have designed and fabricated novel lasers which contain a wideband window of low reflectance amidst the typical interference fringe spectrum. The 750-800-nm region for the low-ripple design has an average reflectance of 5%; the peak-to-peak amplitude of the ripple is 0.25%. The sensitivity of these devices to temperature variations and layer-thickness manufacturing variations is also studied. The low-ripple pump window shifts at a rate of 0.036 nm//spl deg/C, the peak-to-peak ripple of the reflectance varies less than 2%, and the pump bandwidth remains constant, over temperatures ranging from 0/spl deg/C to 100/spl deg/C. The low-ripple structure substantially reduces the temperature and wavelength variation of the pump-field overlap by creating a window of nearly constant reflectance.