A polarization-maintaining photonic crystal fiber hydrogen sensor based on polarization interference

Abstract

The invention discloses a polarization-maintaining photonic crystal fiber hydrogen sensor based on partial polarized light interferences. The polarization-maintaining photonic crystal fiber hydrogen sensor is composed of a broadband light source, a transmission fiber, a polarization controller, a PM-PCF (Polarization-maintaining Photonic Crystal Fiber), a Pd / Ag hydrogen sensitive film, a two-dimensional optical fiber clamp, a constant-temperature gas chamber and a spectrograph. After a polarization state of a light beam transmitted by the broadband light source is adjusted through the polarization controller, the light beam is emitted into the PM-PCF; and the Pd / Ag hydrogen sensitive film is uniformly sputtered on the outer side of a slow axis of the PM-PCF and covers one half of the periphery of the slow axis. A plated film on the surface of the fiber is asymmetrical along the axial direction so that the influences on double refraction of rapid and slow axes, caused by the fact that the Pd / Ag hydrogen sensitive film is expanded after absorbing hydrogen, are different; and polarization directions and phases of slow axis light are changed and the state of rapid axis light keeps unchanged. Two transmission modes are interfered in the transmission fiber and a spectrum is received by the spectrograph. The Pd / Ag hydrogen sensitive film is very sensitive to hydrogen so that the hydrogen concentration of the environment can be accurately reflected by an interference spectrum drifting amount. The polarization-maintaining photonic crystal fiber hydrogen sensor is simple in structure, high in sensitivity and small in temperature drifting, and provides a practicable scheme for online monitoring of the hydrogen concentration.

Description

technical field [0001] The invention belongs to the technical field of optical fiber hydrogen sensing, and in particular relates to a polarization-maintaining photonic crystal optical fiber hydrogen sensor based on polarization interference. Background technique [0002] Hydrogen (H 2 ) has high energy density, and its combustion products are non-toxic and harmless. It is recognized as the most promising secondary energy source in the 21st century. Under the conditions of room temperature and standard atmospheric pressure, the explosive concentration range of hydrogen is very wide (4%~74.2%), the ignition energy is extremely small (0.02mJ), and the strong flammability and explosiveness have great influence on the safety, reliability and Higher requirements are put forward for the response ability of ultra-low concentration hydrogen. [0003] Optical hydrogen sensors, especially fiber optic hydrogen sensors, use light as a medium for hydrogen concentration sensing. Since th...

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Problems solved by technology

The common fiber Bragg grating type hydrogen sensor requires additional temperature compensation measures to suppress the temperature drift of the central wavelength, the detection accuracy is not high, and there is also the problem of temperature cross-sensitivity

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