Terahertz Intracavity Spectrometer

This SBIR Phase I project will 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 differential intracavity laser absorption spectroscopy (ICLAS) which provides up to 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 plan will experimentally demonstrate ICLAS using THz QCLs for the first time. This demonstration will utilize the relevant low-vapor pressure explosive TNT. In addition, sensitivity limits will be determined for a range of other customer-identified compounds. The Phase I option will produce a detailed design for field-deployable prototype threat sensor to be prototyped in Phase II. A feature of the effort is that feasibility will be supported by original terahertz spectroscopic measurements on threat vapors, many for the first time.