Many QCL devices tend toward a laser core design consisting of 30-40 stages (about 1-2 μm thick,) with a device length of 2-5 mm and a laser core width of ~10 μm. The device length is largely constricted by the effects of strain causing bending for particularly long devices. Number of stages and laser core “ridge” width are chosen to prevent overheating.
The number of alternating layers in the laser core causes heat conduction along the growth direction of the device to be greatly reduced from that of the materials used. This means heat flow is much stronger laterally rather than vertically (alogn the growth direction.) Widening the laser core can cause overheating of the device and degrade performance in continuous wave (CW) operation. However, by reducing the number of stages, the vertical heat flow can be balanced to allow for a large amount of CW power to be generated by a device.
Our high CW power devices feature broad area designs with reduced number of stages to maximize CW power out. We project more than 10 W out of a single emitter is possible with proper device optimizations.