New QCL technology’s distributed feedback design enables military applications for infrared countermeasures, infrared beacons and target designators
UCF researchers have invented a quantum cascade laser (QCL) that provides the ultra-high output power, brightness, and beam quality needed for broad-area applications. Example applications include hyperspectral imaging, infrared illumination, and military countermeasures that protect aircrafts against shoulder-fired heat-seeking missiles. Key to the invention is an ultra-thin active region with low thermal resistance and the ability to use angled grating distributed feedback (α-DFB) configurations.
To achieve high peak power, broad-area devices require active regions that are at least 50 µm wide. Yet, conventional QCLs made with deep-ridge configurations tend to overheat when active regions are more than 20 µm wide. Additionally, increases in power usually result in deteriorated or reduced beam quality. Such QCL configurations also negate the spatial-mode filtering properties of α-DFB gratings. These issues have made conventional QCLs poor candidates for broad-area use. In contrast, the UCF invention resolves the heat and beam quality issues by providing an ultra-thin active region (≥ 50 µm wide) with low thermal resistance. It also supports α-DFB configurations for spatial mode selection.
The invention consists of an α-DFB QCL device and fabrication methods. It comprises a substrate, one or more emitting facets, and semiconductor layers forming an ultra-thin active region that dramatically reduces thermal resistance. Also included is a shallow ridge or simple contact-strip configuration to suppress mode reflection at the lateral active region/waveguide interface and an α-DFB grating for spatial mode selection. The new QCL can emit continuous-wave laser output or a pulsed laser output through the emitting facet. Multiple QCLs combined into a W-shaped array can reach optical power levels above 100W into a high brightness beam.
- Provides high power QCL systems that have excellent beam quality
- Much lower resistance; therefore, lower heat dissipation
- Strong spatial mode selection
- Infrared beacons and target designators
- Infrared countermeasures
- Hyperspectral imaging