Reliability Assessment of 940 nm VCSEL Array based on Pulsed Mode Thermal Analysis

In order to obtain a relative accuracy of lifetime prediction of reliability test for VCSEL array device, the junction temperature (Tj) extraction has been investigated and analyzed in this manuscript. We propose a modified array thermal model which is achieved by unit area including 2 × 2 emitters based on the thermal characterizations of single emitter and array device. Adopting the additional parameters of thermal coupling and common thermal dissipation path into the model, peak and average Tj can be analyzed for the VCSEL array within 380 emitters under pulsed or CW operation. To further verify the Tj extraction with a certain pulse condition, accelerated life testing (ALT) was performed for a criteria of 5 % power degradation at operating current (Iop). The array lifetime prediction can be analyzed by the calculation of temperature acceleration factor (EA) and current acceleration factor (n) with the modified Tj value.