All-Fiber CO₂ Sensor Using Hollow Core PCF Operating in the 2 µm Region.

A realistic implementation of an all-fiber CO₂ sensor, using 74 cm of hollow core photonic crystal fiber (HC-PCF) as the cavity for light/gas interaction, has been implemented. It is based on CO₂ absorbance in the 2 µm region. The working range is from 2% to 100% CO₂ concentration at 1 atm total pressure and the response time obtained was 10 min. Depending on the concentration level, the sensor operates at one of three different wavelengths (2003.5 nm, 1997.0 nm and 1954.5 nm) to maintain a high sensitivity across all the working range.