Technical Insight
High-temperature operation of VCSELs (Research Review)
In order for components such as VCSELs to be suitable for commercial applications, they must be capable of operating over a wide range of conditions. F Peters and H MacDougal of Gore Photonics reported 850 nm oxide-confined VCSELs that retain sufficient bandwidth for 10 Gbit/s operation up to 150C (Phot. Tech. Lett. 2001 13(7) 645). Since the limiting factor for high-frequency operation is generally either poor thermal characteristics or parasitics, high-speed devices are designed with small mesas to limit parasitic capacitance. A semi-insulating substrate is utilized, and an air-bridge is used to reach the completely isolated top contact. Because the size of the top contact is very small, the resistance of the DBR mirror becomes significant; this was minimized by optimizing the doping in the DBR.
