Photonic crystal fiber grating temperature sensor with tunable wavelength

Abstract

The invention relates to a temperature sensor. In order to solve the problem that the detecting waveband of the conventional photonic crystal fiber sensor cannot be changed once the photonic crystal fiber sensor is manufactured, the invention provides a photonic crystal fiber grating temperature sensor with tunable wavelength. According to the technical scheme of the invention, a photonic crystal fiber for sensing is provided with a cladding and a long-period grating written in a fiber core, wherein the cladding consists of air vent holes which are in triangular periodical arrangement, the air vent holes in the center of the cladding serve as the fiber core, and the radius of the fiber core is larger than that of the air vent holes in the cladding; temperature sensitive nematic liquid crystals are filled in the fiber core; the central wavelength of the long-period grating is determined by the period of a controlled long-period grating; the refractive index of the nematic liquid crystal changes with the temperature of the surrounding working environment, and the propagation pattern through grating coupling is controlled by controlling the temperature of the working environment of the liquid crystal, so that temperature change represents drifting of spectrum, and thus the wavelength tunable temperature sensing characteristic is realized. The invention is mainly applied to design and manufacture of temperature sensors.

Description

technical field [0001] The invention relates to a temperature sensor, especially an optical fiber grating temperature sensor, in particular to a photonic crystal optical fiber grating temperature sensor with tunable wavelength. Background technique [0002] The long-period fiber grating refers to the periodic change of the refractive index introduced into the core of the fiber, and the period is on the same order of magnitude as the infrared wave, usually hundreds of microns. Fiber Bragg grating sensor obtains sensing information through central wavelength modulation, has the advantages of anti-electromagnetic interference, anti-corrosion, electrical insulation, high sensitivity, low cost, and good compatibility with ordinary optical fibers, and is suitable for precise and accurate measurement. Therefore, making high-sensitivity fiber grating sensors is an important direction for the development of modern sensors. [0003] Photonic crystal fiber is a new type of optical fib...

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the deficiencies in the prior art, the object of the present invention is to solve the problem that the detection band of the conventional photonic crystal fiber sensor cannot be changed after the fabrication is completed, and to provide a sensor that can flexibly control its transmission only by selecting an appropriate grating period. Sensitive band is the wavelength-tunable photonic crystal fiber grating temperature sensor. The technical solution adopted in the present invention is a wavelength-tunable photonic crystal fiber grating temperature sensor. The photonic crystal fiber used for sensing has triangular periodic air holes The composed cladding, and the long-period grating written in the core, the air hole in the center of the cladding is used as the core, the radius of the core is larger than the radius of the air hole in the cladding, and the temperature-sensitive nematic liquid crystal is filled in the core , the central wavelength of the long-period grating is determined by the period of the controlled long-period grating; the refractive index of the nematic liquid crystal changes with the temperature of the surrounding working environment, and the propagation mode coupled through the grating is controlled by controlling the working environment temperature of the liquid crystal. The change of temperature is reflected as the shift of the spectrum, so as to realize the wavelength tunable temperature sensing characteristics

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