.Parameters optimization of π-phase-shifted long-period fiber grating for gas sensing[J].Optoelectronics Letters,2011,7(1):22-25 Parameters optimization of π-phase-shifted long-period fiber grating for gas sensing 蒋秀丽 Laboratory of Photoelectric Functional Films,Shanghai University of Science and Technology； Department of Math and Physics,Shanghai Institute of Electric Power； Abstract:       The gas-sensitive film coated -phase-shifted long-period fiber grating (LPFG), consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period, is proposed for gas sensing. The sensitivity of the sensor is defined by the change rate of the transmission at specific wavelength with respect to the film refractive index. The qualitative and numerical analyses show that to get a high sensitivity, the optimal coupling strength of each long-period fiber grating is $ \sqrt 2 $ \sqrt 2 π/4. With this coupling strength, the longer the grating is, the higher sensitivity the sensor has. By choosing appropriate grating period, a high sensitivity for the film with a certain refractive index and thickness can be attained. Hits: 3957 Download times: 281 View Full Text    Download reader