Quantum cascade (QC) laser core heating is a primary impediment to high device wall plug efficiency (WPE). Here, we demonstrate that efficient photon generation produces a quantifiable reduction in heating of the QC laser core temperature. By superimposing low duty cycle current pulses on a core-heating dc baseline, we observe the instantaneous threshold current and current efficiency evolution as the dc input is varied. From these measurements we recover the laser core temperature Tcore. Results agree well with calculations of Tcore based on measured thermal resistance and WPE. Using the same thermal model for a laser with negligible WPE, we show that the large WPE of the measured device-24% for an 80 K heat sink-results in a core temperature reduction of ∼15 K.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)