Thermal imager using metamaterials
| DWPI Title: Cantilever-based substrate-free terahertz radiation detector for use in focal plane array for active imaging application for illuminating object, has thermal isolation legs whose thermal conductivity id lower than that of actuation legs |
| Abstract: An apparatus and method are disclosed for detecting terahertz radiation at room temperature. A detecting pixel includes a sub-wavelength split-ring resonator, and is mechanically coupled to (but thermally decoupled from) a substrate via a cantilever formed from two materials that have a significant mismatch in their thermal expansion coefficients. Incident radiation causes the split-ring resonator to resonate, thereby generating heat that is transferred to the cantilever, causing the cantilever to flex. An optical readout system includes a secondary light source, such as a laser, that shines on a reflective surface on the pixel, whereby a photodiode detects the reflected light and permits calculation of a relative deflection of the pixel in the nanometer range. An exemplary detector has a noise equivalent power rating of approximately 60 pW/√Hz. |
| Use: Cantilever-based substrate-free terahertz radiation detector for use in a focal plane array for active imaging application for detecting terahertz radiation at a room temperature for illuminating an object. Can also be used for security and non-invasive diagnostic applications. |
| Advantage: The detector is low in cost, and compact and operates at room temperature and can be easily incorporated into a focal plane geometry. The free-standing cantilever is thermally isolated to increase sensitivity and image quality while optical readout of the detector reduces noise issues associated with on-chip electronic detection. The optical readout does not require metal interconnection on each pixel for measuring output as electrical readout system, thus enabling improved thermal isolation. The detector does not require sacrificial layer and silicon/gallium arsenide substrate underneath the cantilevers, thus eliminating adhesion, and hence simplifying the fabrication process. |
| Novelty: The detector has a radiation absorption pad with a split-ring resonator whose electrical resonance frequency corresponds to a wavelength of terahertz radiation greater than a characteristic dimension of the resonator. A detection structure is coupled to a substrate by a flexible free-standing cantilever comprising a set of actuation legs formed from two materials having different coefficients of thermal expansion. A set of thermal isolation legs has thermal conductivity lower than that of the actuation legs. |
| Filed: 10/4/2011 |
| Application Number: US13252821A |
| Tech ID: SD 12214.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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