Thermal resistance evaluation of high-speed VCSELs: an isothermal optical transient technique

A new method for the estimation of the overall thermal resistance of high-speed vertical-cavity surface-emitting lasers (VCSELs) is presented. The method is based on an isothermal optical transient (IOT) approach heavily relying on the following two basic features: 1) the high-speed VCSELs have an optical-electrical transient response much faster than their thermal response, and 2) each operating point, defined by the driving current, the emitted optical power, and the internal temperature of the VCSEL is unique. As a proof of concept, the IOT procedure has been simulated using accurate VCSEL models. These simulations have clearly demonstrated the potential of the IOT method to achieve accurate estimates of the overall thermal resistance of VCSELs.