A new technique for measuring the thermal impedance of junction lasers

A new method is presented to measure the temperature of the optical cavity of a junction laser as a function of the average electrical power supplied to the device. The technique relies upon a null measurement of the exact wavelength of a single Fabry-Perot mode and therefore does not require a preliminary calibration measurement. Because of the small linewidth of the mode, very small (
<0.2\deg
C) temperature differences are easily measured. The method is utilized to obtain the thermal impedance for several different types of bonded stripe-geometry junction lasers.