PT Journal
AU Hübers, H
   Schubert, J
   Krabbe, A
   Birk, M
   Wagner, G
   Semenov, A
   Gol’tsman, G
   Voronov, B
   Gershenzon, E
TI Parylene anti-reflection coating of a quasi-optical hot-electron-bolometric mixer at terahertz frequencies
SO Infrared Physics & Technology
JI Infrared Physics & Technology
PY 2001
BP 41
EP 47
VL 42
IS 1
DI 10.1016/S1350-4495(00)00057-8
DE NbN HEB mixers; anti-reflection coating
AB Parylene C was investigated as anti-reflection coating for silicon at terahertz frequencies. Measurements with a Fourier-transform spectrometer show that the transmittance of pure silicon can be improved by about 30% when applying a layer of Parylene C with a quarter wavelength optical thickness. The 10% bandwidth of this coating extends from 1.5 to 3 THz for a center frequency of 2.3–2.5 THz, where the transmittance is constant. Heterodyne measurements demonstrate that the noise temperature of a hot-electron-bolometric mixer can be reduced significantly by coating the silicon lens of the hybrid antenna with a quarter wavelength Parylene C layer. Compared to the same mixer with an uncoated lens the improvement is about 30% at a frequency of 2.5 THz.
ER