Characteristics Of Special Structure Long-period Fiber Gratings Based On Arc Discharge Effect

Fiber grating is promising optical device with the properties periodically varying along the fiber.Optical sensors based on fiber grating are of high accuracy,small dimension,and interference resistance.There is a vast amount of information available on procedures for using electrical arc discharges to make low-loss splices when connecting optical fibers or fabricating optical devices.However,there is a relative lack of systematic information on the effects of arc discharges in optical fibers in nonsplicing continuous fiber configurations.As of now,there has been no general systematic investigation of arc-discharge effects that include the simultaneous measurement of residual stress profiles and refractive index profiles.Stress and index profiles have not been measured as a function of discharge current or discharge time.Further,in sensor technology,there is a desire to measure one or more limited small volume regions.Thus,there is a need for short,compact devices.In order to address the above purpose,the present work is as followed.1.The concurrent effects of residual stress and refractive index in single-mode optical fibers caused by electrical arc discharge were characterized in detail for the first time to the best of our knowledge.Concurrent RS and RI profiles were presented as a function of discharge current and discharge time.2.The prospects and possibility of LPFGs fabricated based on the relaxation of mechanical stress within the core were shown.A new description was presented that predicts the RI modulation,and coupled-mode theory was used to simulate the LPFG transmission spectra.3.A new concept for long-period fiber grating structures,the DF-LPFQ has been introduced.This device is fabricated by splicing dissimilar fiber types together periodically.Prototype devices are fabricated.The transmission spectra with respect to the period length have been investigated4..Moreover,the resulting devices are used as a sensor and the strain and temperature sensing characteristics are described.