The invention discloses a
photonic crystal optical fiber methane sensing device based on modular interference. The device is composed of a
broadband light source, an
optical circulator, a
photonic crystal optical fiber methane sensor cladding an air hole coated
polymer sensitive film, a testing
air chamber, a switching valve, a quality flow controller, a
spectrum analyzer and a computer, wherein the
optical fiber methane sensor consists of a single mode
fiber, a
photonic crystal optical
fiber and a
welding area of the two fibers; the adopted photonic
crystal optical
fiber refers to an endless single mode
solid core photonic
crystal optical fiber; the
polymer sensitive film refers to a
polycarbonate resin methane sensitive film containing a cage molecule E-(OC2H5)6, and the inner wall of the cladding air hole of the photonic
crystal optical fiber is coated with the film by virtue of an air pressure driving device; when the to-be-tested
methane gas acts with the sensitive film on the inner wall of the cladding air hole of the photonic crystal optical fiber, the
refractive index of the sensitive film changes, the reflection interference spectrum characteristic
wavelength of the sensor is moved, the average movement amount shown in the description of the reflection interference spectrum characteristic
wavelength before and after contacting the sensor with the
methane gas is analyzed, so that the concentration of the to-be-tested
methane gas can be obtained. The device disclosed by the invention has the characteristics of high sensitivity, high stability,
high selectivity and the like.