Portable Terahertz Imaging System

This Phase II SBIR proposal describes a development program aimed at designing and fabricating a terahertz quantum cascade (QC) laser from gallium arsenide-based epitaxial material grown by the metalorganic chemical vapor deposition (MOCVD) technique. Previously produced terahertz QC lasers were fabricated from the more complex indium phosphide-based materials, and were grown by molecular beam epitaxy, which is inherently slower and more expensive than MOCVD. The lasers produced during Phase II will be evaluated in a terahertz imaging system designed and assembled during Phase I. Phase I also demonstrated, for the first time, that it was possible to grow an MOCVD terahertz QC laser epitaxial wafer structure identical to the MBE-grown structure used by MIT to produce the first US terahertz QC laser last year. During Phase II, several candidate terahertz laser epitaxial structures will be designed, grown, processed, evaluated, and incorporated into a terahertz imaging system. The epitaxial layer structure designs will be carried out at the University of Illinois, and epitaxial wafer growth, wafer processing, laser fabrication and evaluation will be carried out at Spire. Terahertz QC lasers will be incorporated into the existing Spire terahertz imaging system, and terahertz imaging feasibility will be demonstrated.