Tunable Erbium-doped Fiber Laser Based On In-line M-Z Filter

With the rapid development of high capacity communication system,the performance of the laser light source has made obvious progress.Tunable fiber laser has been an ideal choice for channel laser source of WDM all the time,and has flexibly provided laser source to different channels.A larger flexibility of network and more efficient wavelength supply plan will be provided to operators,and lower costs will be achieved.It is an important means of intelligent optical network.In recent years,more and more scholars introduced in-line filter based on mode interference between fiber core mode and cladding mode into the laser cavity.Tunable Erbium-doped fiber laser based on in-line M-Z filter has a compact construction and flexible tunable methods as well as a great value of practical application.In this paper,the tunable Erbium-doped fiber laser based on in-line M-Z filter has been introduced.The main contents include:1.The characteristic,significance and classify of the subject are summarized.Current situation and focus of study have been analyzed.The rise and current situation has been introduced,and the direction of the future study with tunable Erbium-drop fiber laser has been showed.2.Firstly,fundamentals of fiber laser and cavity have been summarized.Secondly,construction and theory of all fiber M-Z filter have been analyzed.Thirdly,construction and theory of in-line M-Z filter have been analyzed.3.Tunable Erbium-doped fiber laser based on cascade-structure and parallel-structure was proposed.In the experiment of tunable Erbium-doped fiber laser based on cascade-structure of in-line M-Z filter and Sagnac filter,cascade structure increases SMSR.Because in-line M-Z filter was sensitive to the change of temperature,a tunable 4 wavelength output laser was achieved by changing the temperature.Taking one of the wavelengths for example,when the temperature was turned from 30? to 150?,the wavelength was turned from 1548.5nm to1557.4nm.And in the experiment of tunable Erbium-doped fiber based on parallel-structure of in-line M-Z filter and FBG,when the temperature was turned from 30?to 190?,the central wavelength generated by the branch of spherical-shape structure was varied from 1551.6nm to 1561.8nm.The lose difference of the two branches was changed by adjusting the variable optical attenuator(VOA),and the laser was switched between the single-wavelength mode and the dual-wavelength mode.4.An erbium-doped fiber(EDF)laser based on a cascade structure consisted of in-line M-Z filter and traditional M-Z filter was proposed.In-line M-Z filter was encapsulated into an encapsulation tube,which was full of magnetic fluid.Taking use of the magnetic control refractive index of magnetic fluid,changing the distance between magnet and the magnetic fluid can change the characteristics of the magnetic field surrounding the in-line M-Z filter,and change the refractive index of magnetic field.When the magnetic field strength increased from 0mT to 21 mT,output laser was tuned from 1528.7nm to 1526.6nm.