J. Korean Ceram. Soc. > Volume 39(2); 2002 > Article
 Journal of the Korean Ceramic Society 2002;39(2): 210. doi: https://doi.org/10.4191/kcers.2002.39.2.210
 4.3 μm 파장 Optical Band-Pass Filter의 제작과 CO2 감도 특성 이상훈, 김수현, 김광호 부산대학교 무기재료공학과 Fabrication and CO2-sensing Characteristics of Optical Band-Pass Filter for 4.3 CO2 Wavelength Sang-Hoon Lee, Soo-Hyun Kim, Kwang-Ho Kim Department of Inorganic Materials Engineering, Pusan National University ABSTRACT Optical Band-pass Filter(BPF) for the selected wavelength of 4300 nm was designed and fabricated on Si wager by alternately depositing Ge and $SiO_2$ thin layers by an electron beam evaporation technique. The fabricated BPF showed the optical transmittance characteristics of 58.2% with FWHM(Full Width at Half Maximum) of 204 nm at 4300 nm, but showed the transmittance less than 5% due to the reflectance over all the wavelength ranges except 4300 nm band. The $CO_2$ sensitivity of BPF was investigated with the transmittance as a function of $CO_2$ gas concentration using a sensing cell attached to FT-IR instrument. The transmittance of BPF was almost linearly decreased with increasing of $CO_2$ concentration in the range of from 500 to 5000 ppm. The sensing structure using double BPFs showed higher slop of transmittance vs $CO_2$ concentration, and thus higher gas sensitivity than that using a single BPF, even though the former had relatively lower transmittance. Key words: $SiO_2$, Ge, Optical filters, BPF, Gas-sensor, $CO_2$ gas
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