SBIR-STTR Award

This SBIR Phase I proposal is aimed at the development of the ultra-sensitive detector for the far infrared (FIR) and terahertz (THz) bands of electromagnetic radiation. The device is inherently optical, operates at room temperature and of submillimeter size. The proposed technology is based on coupling the radiation to be measured to the mechanical degree of freedom of an optical microcavity and using the optical degree of freedom to get the information about the radiation field out. That is, the mechanical response of the microcavity to the incident radiation drives changes in its optical mode field. These changes manifest themselves as frequency shifts of the cavity optical resonances commonly known as Whispering Gallery Modes (WGM) which are measured using a tunable diode laser and a photoreceiver. In the Phase I research, measurements of FIR-THz radiation will be accomplished using microspherical and microtoroidal resonators, and the sensor operational model will be developed. Utilization of radiation pressure backaction cooling of the cavity to reduce local temperature and further increase sensitivity of detection is envisioned for the continuing research. Our goal is to demonstrate robust, field capable, ultra high sensitivity miniature FIR-THz detectors operating in room temperature environment.

Keywords:
Long-Wavelength, Far-Infrared, Terahertz, Micro-Resonators, Mechanical-Optical Coupled Cavities, Radiation Detector

This DoD ARO SBIR 2012 Phase II Project is aimed at the development of a micro-optical ultra-sensitive, room temperature detector for the far infrared (FIR) and terahertz (THz) bands of electromagnetic radiation. The sensor relies on monitoring optical resonances commonly known as Whispering Gallery Modes (WGM) of dielectric micro cavities. In Phase I, an operational model for this WGM radiation detector was developed. Model calculations demonstrated high potential of the technology for ultra-sensitive detection of FIR-THz radiation using a sensor of a sub-millimeter size. A breadboard prototype developed in Phase I was capable of measuring THz radiation power at least an order of magnitude smaller than that detectable by a state-of-the-art THz detector. Phase II effort will concentrate on systematic studies of the detector characteristics as a function of structural parameters such as geometry, size, and material of the microcavity, the development of integrated deployable detector prototype, and investigation into robustness and reliability issues in the context of a field sensor. An imaging experiment with a biological system with a concealed foreign object will demonstrate the detector spatial recognition capabilities. An exploratory study for assembling WGM micro-cavities in 1D and 2D arrays will outline the technology prospective.

Keywords:
Radiation detector, THz detector, far infrared detector, optical micro-cavity, mechanical-optical cavity, whispering gallery modes, WGM, spectral shift