NASA SBIR 2005 Solicitation


SUBTOPIC TITLE:Passive Microwave
PROPOSAL TITLE:High Reliability Oscillators for Terahertz Systems

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
979 Second Street SE, Suite 309
Charlottesville ,VA 22902 - 6172
(434) 297 - 3257

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
David W Porterfield
979 Second Street SE, Suite 309
Charlottesville, VA  22902 -6172
(434) 297 - 3257

Terahertz sources based on lower frequency oscillators and amplifiers plus a chain of frequency multipliers are the workhorse technology for NASA's terahertz missions. The design and optimization of individual multipliers is fairly well understood. However, the complex interactions within a chain of nonlinear multipliers often limit the system performance. Specific manifestations of these interactions include rapid variations in power as the frequency or input power are tuned, including nulls and power surges that can damage individual components. These effects limit the useful bandwidth of terahertz sources, degrade system reliability and greatly increase the time and cost of developing systems for a particular application. Today, these problems are mitigated through the use of mechanical tuning or bias adjustments at each frequency, the laborious tweaking of each component in the chain until acceptable system performance is achieved, or reduction of the system bandwidth and/or power specifications. This proposal concerns the first systematic study of the complex interactions between cascaded nonlinear multiplier stages, with the goal of developing new multiplier and system designs that reduce these unwanted effects. The resulting terahertz sources will achieve greater efficiency, bandwidth, reliability and ease-of-use, as well as shortened system design cycles and greatly enhanced manufacturability.

This technology will enable the development of more powerful and frequency agile terahertz sources to be used as local oscillators for heterodyne receivers. A wealth of molecular resonance lines occur between 100 GHz and 5 THz. These resonances allow astronomers and atmospheric researchers to study the chemistry and dynamics of the Earth's atmosphere, molecular clouds in star forming regions and the atmospheres of other planets. NASA leads the world in the use of terahertz technology for the study of atmospheric chemistry and astrophysics from aircraft, balloons and spacecraft. Proposed missions include SIRICE, an atmospheric probe; VESPER a probe that would study the atmosphere of Venus, and SIGNAL a Mars instrument to perform a constituent survey of the atmosphere. The Phase 1 effort will demonstrate a critical multiplier chain for the SIRICE Sub-Millimeter Radiometer and in Phase 2 additional prototypes for other frequency bands of SIRICE will be demonstrated.

Scientific applications of this terahertz technology include chemical spectroscopy, radio astronomy, plasma diagnostics, biomaterial analysis, electron spin resonance, and diagnostic instruments for particle accelerators. Other terahertz applications related to military requirements include compact range radars, covert communications systems, imaging systems, and chemical, explosive and bioagent scanners. Biomedical researchers envision the use of terahertz imaging and spectroscopy for the real time analysis of skin diseases such as skin cancer. Potential large-scale commercial applications of the proposed terahertz technology include portal security imagers and scanners, medical diagnostics for clinical use, last-mile data links, and industrial process control. Many of VDI's present customers are scientists and engineers that are developing these potential applications and VDI is building initial ties to larger corporations interested in exploiting the terahertz frequency band. Compact, reliable and manufacturable terahertz sources with improved power and bandwidth are critical for these emerging applications.

NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.


Form Printed on 09-19-05 13:12