AWG (Array Waveguide Grating) differential demodulation based intensity detection type PCF-LPG (Long-Period Grating Written in a Photonic Crystal Fiber) stress sensor

Abstract

The invention relates to an intensity detection type photonic crystal fiber long period grating stress sensor based on waveguide array grating differential demodulation. Two ports of the photonic crystal fiber long period grating are respectively optically connected to incidence ends of a broadband light source and the waveguide array grating. A second channel and an eighth channel of the waveguide array grating are two outgoing ends optically connected to a photoelectric converter and a signal processing unit. The photonic crystal fiber long period grating is a sensing element; and the waveguide array grating, the photoelectric converter and the signal processing unit form a demodulator of the optical fiber sensor. Through the sensor and the device, the interference brought by dithering of the light source and various instability factors of a sensing system is effectively eliminated, and the accuracy of the system is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and relates to an intensity detection type photonic crystal fiber long-period grating (long-period grating written in a photonic crystal fiber, PCF- LPG) stress sensor and device stress sensor. Background technique [0002] Long-period fiber grating (long-period fiber grating, LPG) is a transmission type optical fiber device. The resonant wavelength and amplitude of LPG are very sensitive to changes in the external environment, and have better temperature, bending, and refractive index sensitivities than ordinary fiber gratings. However, when using LPG to measure physical quantities such as stress, the cross-sensitivity to temperature greatly limits the application of LPG. Photonic crystal fiber (PCF) is a new type of optical fiber with many excellent optical properties, such as temperature insensitivity. The LPG made of photonic crystal fiber with temperature insensitivity can e...

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the problem of low precision of the demodulation unit of the photonic crystal fiber long period grating sensor in the prior art, and to provide an intensity detection photonic crystal based on the differential demodulation of the waveguide array grating (Array WaVeguide Grating, AWG) Optical fiber long-period grating stress sensor, this demodulation scheme can effectively eliminate the interference caused by light source jitter and various unstable factors of the sensing system

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