Research On 930 Nm Passive Mode-locked All Fiber Nd-doped Fiber Laser

Emission wavelength at 900 nm to 980 nm laser can produce 450 nm to 490 nm blue light after frequency doubling,which has important application values of the high density optical data storage,underwater communication detection,laser color-display,biomedical,and many other fields.930 nm neodymium-doped fiber laser after frequency conversion can produce 465 nm blue light,compared with 980 nm frequency doubling ytterbium doped fiber laser of 490 nm blue green light is purer,which can replace the existing blue semiconductor lasers,argon ion laser,become the new tendency of blue light.In addition,the 930 nm ultrashort pulse laser has important research value in the field of biological microscopic imaging,can be used in biological tissue depth imaging and the observation of living cells.So far,the 930 nm band neodymium-doped mode-locked fiber lasers are more focused on nonlinear polarization rotation.The lasers contained many space components,and the structures are more complicated.So,this paper systematic researches high integration,compact structure of the 930 nm neodymium-doped fiber laser,its main content for the following parts:The first part demonstrates 930 nm mode-locked fiber oscillator and amplifier related theories.Starting from the absorption of neodymium ion emission cross section,analyses the key issues to generate 930 nm laser,namely the inhibition of four-level system of vibration and reduce 930 nm laser ground state absorption.Then,the paper introduces the way and principle of the mode-locked,SESAM and other critical devices.The SESAM mode-locked equation of nonlinear Schrodinger equation is also introduced.Finally,the dispersion and nonlinear effect in the process of amplification effect on the output characteristic are analyzed.The second part carried out the experiment and simulation study of 930 nm all fiber oscillator.Firstly,the cavity was made up of FBG and SEAM,adopted the ordinary commercial neodymium-doped fiber as gain medium.Generated an average output power of 1 mW picosecond short pulse with the repetition frequency 28.2 MHz.The pulse width is 8.8 ps,and 3 dB spectrum width is 0.37 nm.The oscillator is running in positive dispersion regime,the output pulse spectrum presents the sharp edge of dissipative solitons mode-locking.Using CFBG to set up oscillator,generated the average output power of 0.45 mW,with repetition frequency of 25 MHz.The pulse width is 8.6 ps with Kelly sideband spectrum,which is typical soliton mode-locking.Used fiberdesk software to simulate the oscillator.The third part has carried out experimental study of 930 nm all optical fiber amplifier and pulse compression.Using W-type neodymium-doped fiber to construct optical fiber amplifier,the type of FBG cavity mode-locked oscillator used to power amplification.The amplifier generates the average power of 117 mW mode-locked stable pulse output,power amplification reached more than 100 times.The out-put pulse center wavelength is 930 nm with pulse width of 8.8 ps.The repetition frequency is 28.2 MHz and the10 dB spectral width is 2.98 nm.Then,using the diffraction grating to compress the pulse width,generated the pulse width of 5.5 ps laser output,with average power is 40 mW.