Researches Of Polarization Maintaining Optical Fiber On The Design,Preparation,Measurement And Application

Polarization-maintaining optical fiber has been widely used in the field of optical fiber communication,optical devices and optical fiber sensors.In particular,the optical fiber lasers and optical fiber gyro have inestimable applied value in the military field.Therefore,polarization-maintaining fiber has become a research focus at home and abroad.In this paper,the design,preparation,measurement and application of the polarization-maintaining fiber have been intensive studied.(1)The parameters measurement of polarization-maintaining optical fiber.Based on the testing principle and computation model,the measurement system for the beat-length,extinction ratio and crosstalk was set up.(2)The design,preparation and application of a new type of polarization-maintaining photonic crystal fiber.We report on a new kind of highly birefringent and highly nonlinear photonic crystal fiber with a row of sub-micron air hole in the fiber core.The parameters of birefringence,nonlinear and dispersion coefficient of the fiber was simulated by finite element method.It is found that the birefringence of the fiber can reach up to at the wavelength of 1550 nm.Using this fiber as a nonlinear medium,an efficient generation of a tunable supercontinuum was demonstrated by pumping with 15 ps pulses of 1040 nm laser radiation,which is located in the normal dispersion region.It is experimentally found that the polarization of pulse has a significant influence on the generation of the supercontinuum.When the linear polarization of the input pulse matches with the direction of the main axis of the fiber,the supercontinuum could be broadened over wavelength range of 800-1500 nm,and the extinction ratio is 21.2 dB.The polarization direction of the output SC is found to coincide with the pump pulse.When the angle between the polarization of the input pulse and the fast axis was increased to 45 degrees,the output supercontinuum was circularly polarized and become narrowest,which extending from 900 to 1300 nm.So we can realize wide tuning of a supercontinuum by only changing the polarization direction of the incident pulse.(3)The design,preparation and measurement of the Yb-doped double-clad polarization maintaining fiber.This type fiber is the key device of high power fiber laser,which has been used in military fields such as laser weapon.The stress model is proposed to investigate the structure parameters of different stress application polarization-maintaining fiber,and the structure design is accomplished.According to the design results,The MCVD(modified chemical vapor deposition)method and the solution doping method were used to prepare the Yb-doped double-clad fiber preform.The preparation and processing technology of the fiber preform and stress rod was studied,such as high-concentration uniform doping technique,the punching process,the polishing technology and so an.The Yb-doped double-clad polarization maintaining fiber was prepared.The beat-length is 3.74 mm and the birefringence is 2.83 × 10-4.A laser was set up by the fiber.The output power reached up to 11.34 W when the input power was 17.88 W,and the extinction ratio is 21.2 dB.