Novel technique for determining internal loss of individual semiconductor lasers

A novel and accurate technique for measuring the internal losses of semiconductor lasers is demonstrated. The technique is based on two measurements: the injection current required for reaching material transparency and the corresponding ripple in the spontaneous emission spectrum. This method, which is independent of the internal quantum efficiency, allows the measurement of individual laser chips rather than an ensemble of chips, and can also be used to determine the loss dependence on wavelength and temperature.