Terahertz Intracavity Spectrometer

This SBIR Phase II project is to develop a hand-held sensing and alarm system for ultra-trace concentrations of chemical gases, biological aerosols, and explosive vapors. Unprecedented sensitivity will be achieved by intracavity laser absorption spectroscopy (ICLAS) which provides kilometer effective optical path lengths in a device with centimeter dimensions. Innovations include the use of semiconductor quantum cascade lasers (QCL) that operate in the terahertz region of the electromagnetic spectrum, a region rich in molecular signatures but under-utilized for spectral sensing. The Phase I work theoretically investigated the operational parameters and sensitivity limits of a THz ICLAS system, showing that it would be suitable for detection of vapors at ppb levels. A THz QCL ICLAS system was bread-boarded and the major components of a complete ICLAS experimentally demonstrated. Phase I option experiments will refine the detailed design for the Phase II field-deployable prototype threat sensor. The core threat sensor will be accessorized for sampling and sensing vapors inside sealed shipping containers and for screening passengers.