Design of High-Reflectance Fabry-Perot Interference-Cavity Plane Mirror and Measurement of Terahertz Wavelength
Wavelength is a crucial parameter for terahertz sources,and the Fabry-Perot(F-P)interferometric method is the preferred approach for measuring terahertz-source wavelengths.However,employing a high-resistance silicon wafer as the interference-cavity plane mirror presents challenges such as low reflectivity,a narrow applicable frequency band,and imprecise stripe precision;consequently,the demands of high-precision wavelength measurements cannot be satisfied.Hence,a series of interference chamber silicon-grid plane mirrors,which comprises high-resistance silicon wafers plated with a periodic metal grid,were designed and processed.These mirrors demonstrate a reflectivity exceeding 87%in the 0.08‒0.53 THz band.The F-P interferometer successfully measures the wavelengths of 0.096 THz/0.14 THz avalanche sources and a 0.315 THz Schottky source,where optimal measurement results are yielded with wavelength errors of 0.16%,0.33%,and 0.54%,respectively.Compared with measurements using high-resistance silicon wafers,this approach significantly improves the interference stripe precision and the half-peak width of the transmission peak.The simplicity of the structure facilitates ease of fabrication,thus contributing significantly to advancements in terahertz-wavelength measurement accuracy and related terahertz devices.
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