High Power Mid-IR Semiconductor Lasers for LADAR
Abstract
The growing need for antimonide-based, room temperature, 2-5 micrometers, semiconductor lasers for trace gas spectroscopy, ultra-low loss communication, infrared countermeasures, and ladar motivated this work. To extend the wavelength of semiconductor lasers beyond 2 micrometers, increased arsenic content has been needed to reduce the bandgap and maintain a lattice match to GaSb. This has resulted in degraded performance due in part to a smaller valence band offset. In this work, the need for lattice match between the active region and the GaSb substrate is avoided by the use of metamorphic AlInSb buffer layers. This provides a virtual substrate to extend the wavelength of GaInSb quantum wells. With the use of lattice constants larger than GaSb, the need for arsenic has been eliminated resulting in pure antimonide crystals, which provides for large valence band offsets. Samples are grown by solid source molecular beam epitaxy. The AlInSb metamorphic buffer layer is a superlattice consisting of alternating layers of AlxInl -xSb and AlyInl -ySb where the indium content and thickness ratios are chosen to provide the desired average indium content. Using these buffer layers, optically pumped GaInSb/AlGaInSb multiple quantum well lasers with as much as 76% indium content in the quantum well and emission wavelength as long as 3.3 micrometers at room temperature have been achieved. The best performing room temperature laser emits at 2.8 micrometers with a threshold power density of 169 W/cm2 and a differential quantum efficiency of 28%.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 26, 2003
- Accession Number
- ADA419059
Entities
People
- Luke F. Lester
Organizations
- University of New Mexico