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|Advance characterization of mid-IR type II lasers|
"W" design lasers
|Gain in broad area mid-infrared diode W lasers (3-3.1 Ám) has been measured using lateral mode spatial filtering combined with the Hakki-Paoli approach. The internal optical loss determined from the gain spectra is 18-20 cm-1 and nearly the same for the devices with either 10- or 5- period active regions. The optical loss is found to be constant in the temperature range between 80 and 160 K. Analysis of the differential gain and spontaneous emission spectra shows that the main contribution to the temperature dependence of the threshold current is Auger recombination, which dominates within almost the entire temperature range studied (80-160 K).|
Optical loss and gain have been measured at different temperatures and excitation levels in type II Quantum Cascade Lasers (QCL) for a first time. A weak temperature increase of the total optical loss has been found. Temperature increase of total optical loss together with strong gain saturation limit the maximum cw operation temperature at 141K. The reason for the optical gain saturation at higher temperatures is the heating of the active area in CW mode.