Method to measure thermal impedance for all-active lasers using the athermalisation condition

Thermal impedance is an important material property which can be used in the design, optimisation and operation of semiconductor lasers. In this study, a new method is proposed for measurement of thermal impedance for all-active semiconductor lasers, using the athermalisation condition. This method is capable of measuring thermal impedance of several device sections at the same time for simple devices, while being capable of measuring the thermal impedance of the device as a whole for more complex structures. Three DBR devices of the same material properties were evaluated and the average impedance length product ( Z th L ) was determined to be 29.3±2.1 o C μ m/mW and 39.33±2.8 o C μ m/mW for the gain and grating sections respectively. Additionally, thermal impedance length product of the entire widely tunable Vernier device based on the same material was also determined to be 31.3±0.5 o C μ m/mW.