Characteristics And Sensing Applications Of Photonic Crystal Fiber Grating

Photonic crystal fiber grating is a special optical passive device,which is one of the most rapid development in recent years.Compared with traditional optical fiber,photonic crystal fiber grating has many advantages,such as anti-electromagnetic interference,small size,low loss and so on.It is widely used in the field of the optical communication and optical sensing.The paper designs two kinds of new photonic crystal fiber grating structures by COMSOL software,analyze the characteristics of the mode field and birefringence by comparison.The spectral characteristics and sensing characteristics of the photonic crystal fiber grating under different structural parameters and external environment are simulated by MATLAB software.Two kinds of new photonic crystal gratings are designed by COMSOL software.Under the same structural parameters,the mode and birefringence characteristics of them are analyzed and compared.Select the photonic crystal fiber with elliptical air-hole structure as the object of study,analyse the influence of birefringence and loss characteristics under different radius of the core and the ellipticity of the cladding.Combine the data obtained by COMSOL with MATLAB software,the relationship of wavelength and spectral properties on different grating length and modulation depth is analyzed.The result shows,with the increase of grating length and modulation depth,the reflection spectrum of the photonic crystal Bragg grating will gradually increase,but the increment gradually decreases.At the grating depth of 4100.2-?,the reflectivity of the grating is maximized.It can be seen that,we can obtain desired reflectivity by setting the appropriate parameters.It introduces the sensing theory of fiber grating.The sensing characteristics of the photonic crystal fiber with elliptical air-hole structure in temperature and stress is discussed.The simulation result shows:with the increase of temperature,the resonant wavelength of the photonic crystal fiber grating drifts to the long wavelength direction,and the trend is obvious;with the increase of strain,the resonant wavelength of the spectrum aiso drifts to the long wavelength,but the trend is very small,which can be ignored.It can be seen that,the structure of the photonic crystal fiber grating is suitable for the production of temperature sensors.