Modeling of surface-emitting lasers

Abstract

Short-cavity surface-emitting semiconductor lasers are potentially useful for highly parallel, optical signal processing and for communication systems. Because of their short cavity lengths, surface-emitting (SE) lasers are expected to be single-mode and to have a high modulation bandwidth. By means of noise-driven rate equations1,2 typical SE lasers are modeled so as to produce photon statistics, relative-intensity noise (RIN) as a function of frequency, and relaxation-oscillation frequency. An example is a 2.7/µm long bulk SE laser simulated at a computer work station. The one µs run at 0.1 ps steps takes 4 minutes to produce photon statistics when the SE laser is biased at 1.5 times the threshold current of 0.89 mA. The main mode is well defined, and the side mode acts as noise with an average side-mode suppression ratio of -29 dB. The relaxation oscillation frequency is 1.7 GHz and is lower than expected. However, the photon lifetime is 2 ps because of the high mirror reflectivity. The characteristics of other SE laser structures, such as quantum-well structures, will also be discussed.