Superconducting Thermal Spreader Enabled MWIR Band-IVb Quantum Cascade Laser with 65 W Average Output Power

For many detectors and sensors, an output signal modulated at MHz frequencies with a high duty cycle (QCW operation) is indistinguishable from a CW signal. Therefore, such systems can be based on QCW lasers without compromising any practical system functionalities. Transitioning to the QCW operation opens up a vast QCL design optimization space for radically improving QCL average brightness, which is leveraged in this program. When a QCL is operated in the pulsed regime, the laser core temperature reduces down to a heat sink temperature on a scale of hundreds of nanoseconds during the OFF cycle. This leads to a significant reduction in average temperature over a full ON/OFF cycle compared to a laser core temperature in CW operation. Lower core temperature enhances laser gain and, as a consequence, its peak power. Therefore, the tradeoff between laser pulse uptime and a duty cycle can be optimized to reduce temperature buildup in the laser core to a degree where average power achieved in QCW operation significantly exceeds that for CW operation. Under this program, IRGLARE is developing a new QCL design optimized for QCW operation with ultra-high average brightness.