Sensor for measurement of hydrocarbons concentration based on optic fiber

Measuring system based on Photonic Bandgap Fiber (PBGF), which will be able to detect, distinguish and measure the concentration of various aliphatic hydrocarbons is proposed. Such a system can be applied on each stage of fuel evaluation, production, distribution and storage of petroleum products. Aliphatic hydrocarbons absorption spectra show several peaks around 1400-1600 nm wavelength. Thus, tunable lasers with 20 micron core photonic bandgap fiber matching above wavelengths were chosen for the optical measurement system. Measurements were performed at a low pressure to eliminate pressure broadening effect and to sharpen the absorption peaks. The sensitivity of measurement increases with increasing of the fiber's length. Length of fiber was adjusted using several methods. The best results were obtained using argon ion beam cutting. The angled cut was performed to improve signal to noise ratio.