ASL Optoelectronics Development

Spectroscopy at wavelengths beyond the telecommunications band (>1.55 µm) is technologically challenging due to the fact that efficient optical sources and detectors are not readily available. A typical tungsten-halogen bulb operating at 3000 K emits light from the UV to the far infrared, however due to the broadband nature of the emission, it is rather inefficient in any given narrow detection band. Furthermore, the intensity of the emission from the halogen bulb is peaked near 1.0 µm and rapidly decreases beyond that. Further limiting the practicality of thermal emission sources is the short lifetime of such devices, which is typically in the range of 100-4,000 hours. By contrast, solid-state sources like LEDs and laser diodes are narrow band emitters and one can often make use of the entire emission spectrum. Additionally, device lifetimes are typically 5,000-25,000+ hours, substantially reducing the frequency of emitter changes.

ASL is actively working to develop high brightness optical sources for infrared spectroscopy in the 2-12 µm wavelength range. A particularly attractive material system for this work is the III-V compound semiconductor family, specifically antimonide-based materials. By selectively choosing alloy compositions and layer thicknesses, multilayer structures may be grown which have optical and electronic properties which are quite different from the constituent bulk materials. This flexibility allows a wide range of materials and devices to be developed, with properties which can largely be tailored to specific applications. We have extensive experience in design, growth, and fabrication of novel III-V semiconductor heterostructure emitters and detectors, with operating wavelengths spanning from the mid- to long-wave infrared.

ASL has in-house capabilities for device design, fabrication, and characterization, and relies on an external vendor for molecular beam epitaxially (MBE) grown device wafers. We have teamed with IQE Inc., a world-wide supplier of epitaxially grown wafers, in an effort to produce high quality solid state emitters.