Fabrication Of ?-phase Shifted Fiber Bragg Gratings And Application In Narrow Linewidth Erbium-Doped Fiber Lasers

? phase-shifted fiber Bragg grating(?-PSFBG)is a special kind of fiber Bragg gratings,there is a ?-phase shift in the refractive index modulation of the fiber core along the fiber axial,leading that there is an ultra-narrow band in the transmission spectrum.It is widely used in distributed feedback lasers,all-optical switches,high precision sensors and so on.One of the most important applications is the narrow band filter used in narrow linewidth fiber lasers.Narrow linewidth fiber lasers have been intensely studied because of narrow linewidth and low noise.However,the current output power is only tens of mW,which can not meet the needs of some applications,such as fiber gas laser.In this context,?-PSFBG is designed and manufactured,and the experimental research on narrow linewidth fiber laser based on ?-PSFBG is carried out.The details are as follows:1.The characteristics of the reflectivity,transmissivity and the linewidth of transmission window of the ?-PSFBG are analyzed by using the transfer matrix theory,and the influence of grating length,modulation depth and position of phase shift on the transmission spectrum of ?-PSFBG is analyzed by simulation,which provides theoretical guidance for the design and application of ?-PSFBG.2.The writing technology of ?-PSFBG in the system based on UV excimer laser is studied by phase mask method,and ?-PSFBG of 1.55 ?m is fabricated.The transmission spectrum and temperature characteristics of ?-PSFBG are studied,which lay the foundation for the experiment of narrow linewidth fiber laser.3.A ring cavity narrow linewidth fiber laser is constructed using self designed ?-PSFBG and highly reflective FBG.The experiment explores how the different coupling output position and different coupling output ratio influences on the laser characteristics.Output laser of 1.55 ?m with linewidth of hundreds of MHz and average power of watt is realized for the first time,which provides a reference for high power,narrow linewidth fiber laser.4.The temperature tuning characteristics of ?-PSFBG is analyzed theoretically and experimentally.Achieving the laser tuning by controlling the temperature of ? phase-shifted fiber Bragg grating is proposed.The temperature of ?-PSFBG and highly reflective FBG is controlled by TEC,respectively,tuning laser is achieved based on the narrow linewidth ring fiber laser mentioned above.The tuning range is greater than 1 nm,and the wavelength and power of laser is stable.The tuning laser provides a favourable pump power for fiber acetylene gas laser,and procides a simple and feasible way for the tunable fiber laser with high power and narrow linewidth.5.A method of real-time temperature measurement inside fiber laser ultilizing the temperature properties of FBG is proposed,and is verified in the experiment system mentioned above.The variation of fiber Bragg wavelength with temperature is measured in advance,and the temperature inside fiber laser can be rapidly obtained by measuring the laser wavelength online.This work provides a new method of real-time measurement of temperature inside high-power fiber laser.