We present here an optical scheme for a trace methane gas detection system using mid-infrared (MIR) light emitting diode (LED) (λ = 3.3 μm) in a hollow-core fiber (HCF). When light from the MIR LED was focused on the HCF, the latter confines the interaction of light and methane gas within a fiber core of 0.5 mm diameter. The 1-m-long HCF provided enhanced optical path, and optimum light-gas interaction. By employing direct absorption spectroscopy, the detection limit of methane gas concentration was extended to as low as 17 ppb, and the dynamic range was estimated as 42 dB. The 400-nm bandwidth of a MIR LED can cover all strong absorption lines in the vicinity of 3.3 μm. This scheme provides an engineering perspective to realize a low-cost, hand-held methane detector for remote and harsh environments.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry