| 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 |
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| ABSTRACT |
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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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