VERTICAL-CAVITY SURFACE-EMITTING LASERS WITH LOW-RIPPLE OPTICAL-PUMPING WINDOWS

A general technique for numerically optimizing the optical admittances in vertical-cavity structures is used to suppress the interference ri pple 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 enha nce the coupling of pump light into 850-nm vertical-cavity surface-emi tting lasers (VCSEL's). We have designed and fabricated novel lasers w hich contain a wideband window of low reflectance amidst the typical i nterference 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 studie d. The low-ripple pump window shifts at a rate of 0.036 nm/degrees C, the peak-to-peak ripple of the reflectance varies less than 2%, and th e pump bandwidth remains constant, over temperatures ranging from 0 de grees C to 100 degrees C. The low-ripple structure substantially reduc es the temperature and wavelength variation of the pump-field overlap by creating a window of nearly constant reflectance.