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We have developed a novel THz detector which uses the cantilever technology and surface plasmon resonance (SPR)
technology to achieve a high sensitivity. The Micro Electro Mechanical System (MEMS) technology is adopted to
fabricate the detector, which comprise thermo-sensitive bi-material micro-cantilever, prism and optical readout system.
The bi-material of Si3N4 and Al is used to fabricate the micro-cantilever because of the good absorption characteristic for
THz of Si3N4 and the great difference in thermal expansion coefficient of the bi-material for the deformation of the
micro-cantilever. In order to increase the deformation of micro-cantilever, the method of computer simulation is used to
obtain the optimal structure of micro-cantilever and the thickness of Si3N4 and Al. The function of the glass prism is to
make the incident light generate total reflection under certain conditions. The gold film is sputtering on the top of glass
slide using the method of magnetron sputtering and it is necessary for the generation of SPR performance. The optical
readout system can make the change of cantilever bending convert to the change of reflection luminous intensity
proportionally. The heat on the micro-cantilever coming from the THz radiation can lose easily in the air, so the detector
is placed vertically in a cylindrical vacuum chamber which is sealed with quartz glasses and polyethylene lamina at the
two end surfaces respectively. The quartz glass is used for the incidence of visible polarized light and the polyethylene
lamina for the THz radiation. In order to maintain the vacuum performance of the chamber, the mechanical pump and
molecular pump are adopted. In static mode, THz radiation absorption raises the temperature of micro-cantilever, so it
bends proportionally. The micro-cantilever bending changes the thicknesses of the gap between the micro-cantilever and
the metallic thin film on the micro-prism. It will result in a shift of the SPR angle. Therefore, the surface plasmon
excitation efficiency and therewith the measured at a fixed incident angle reflectance of a metallic film will be changed
almost proportionally to the cantilever bending. Consequently, the radiation energy of THz can be determined via the
metallic film reflectivity change. Finally, the technology of image processing is introduced in detail.
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