Research On The Key Issues In Distributed-feedback Fiber Laser Array

Due to the intrinsic wavelength-encoded multiplexing capability,distributed feedback(DFB)fiber lasers are considered as the ideal candidate for the next generation fiber sensing system.However,the extraordinary multiplexing capability has not brought the interest of large scale DFB fiber laser array yet.The maximum scale of DFB fiber laser array remains to be 16,which has hindered the development and application of DFB fiber laser.In this thesis,we investigate the key physical problems in the fiber laser dynamics,aiming to provide guidance for the array scale extension of DFB fiber laser system.In order to increase the multiplexing capacity and optimize the noise level of DFB fiber laser array,the influence of the injection of coherent light,non-resonant light and pump light has been studied.Coherence collapse characteristics of DFB fiber laser due to multiple external reflections is modeled,and the threshold length of two-element DFB fiber laser array is carefully measured.The output power spectrum reshaping of DFB fiber laser array utilizing environment insensitive long period grating(LPG)is proposed to suppress the intensity noise transfer of non-resonant light injection.The longitudinal temperature distribution in DFB fiber laser cavity and the laser performance are tested with increasing pump power,and the performance of active fiber and LPG in high temperature conditions is studied.The main results of this thesis are as follows:1.A novel method to evaluate the phase shift position of asymmetric DFB fiber laser is proposed.A double-end-coupled complex cavity model is established,which provides an effective route to extend the total length of DFB fiber laser by adjusting the array structure.2.Temperature and strain insensitive LPG is fabricated,and nanoscale glass milling with mild thermal annealing is demonstrated,which opens up a new and broader approach to nanoscale engineering technology for optical waveguide.3.Pump induced nonlinear active phase shift chirping and DFB fiber laser quenching are observed.The equivalent physical image of the wavelength detuning is given,and a phase shift compensation method of DFB fiber laser is proposed.4.The excited state lifetime of Er3+ and gain coefficient of an Er3+/Yb3+ co-doped phosphosilicate fiber can be recovered by high temperature annealing.LPG regeneration is demonstrated,and the transition temperatures of different fiber layers are estimated,based on the measurement of the stabilized regenerated LPGs.