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Dissipative Soliton Resonance Mode-locked Fiber Lasers

Posted on:2019-01-16Degree:MasterType:Thesis
Country:ChinaCandidate:J L ChangFull Text:PDF
GTID:2348330563453865Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Various mode locking mechanisms have been investigated in passively mode-locked erbium-doped fiber lasers.Traditional passive mode locker for fiber lasers include semiconductor saturable absorber mirrors(SESAM),nonlinear polarization rotation(NPR),nonlinear optical loop mirror(NOLM),and nonlinear amplifier loop mirror(NALM).Recently two-dimensional materials are used as mode locker,including graphene,black phosphorus.In the negative dispersion regime,the fiber laser operating in DSR region can generate high energy pulse.Stretching the cavity length is an efficient way to boost the pulse energy to a higher level.In 2010,a long-cavity mode locked fiber laser with 8km cavity length and 4μJ pulse energy was reported.In this paper,we demonstrate a figure eight passive mode-locked fiber laser and a tunable long-cavity passive mode-locked fiber laser.1.We establish the simulation model including main parts of the passively modelocked fiber laser,and corresponding nonlinear Schr?dinger equation(NLSE).Setting up initial parameters on the basis of physical truth,we find that the pump strength and spectral filtering bandwidth had great effects on the properties of the generated dissipative solitons.2.We use figure-eight cavity mode-locked fiber laser,when we insert 2km single mode fiber,pump power is 400 m W,the fundamental frequency of the output single pulse energy is highest 42.167 nJ.The experiment is inserted 67 m and 10 m long single mode fiber,the optical soliton spectrum is observed.We can be concluded from the experiment,stretching of the laser cavity length can effectively increase the output pulse energy of single pulse.3.The mode locker is a nonlinear amplifying loop mirror(NALM)with the single wavelength tunable passively mode-locked fiber lasers.The cavity frequency of the laser is 465 kHz because that 404 m SMF is inserted in the cavity.A tunable bandpass filter with ~1nm 3dB bandwidth is inserted into the cavity to realize tunable mode locking.The passive mode-locked laser at 1560 nm center wavelength is investigated in detail.The experimental results indicate that the laser operates in dissipative soliton resonance(DSR)region.When the pump power is 400 mW,the laser generates the rectangular pulses with 10.58 ns pulse duration,70.28 nJ single-pulse energy.When the pump power is 400 mW,the laser keeps stable mode locking status in the range from 1523.4nm to 1575 nm.During the whole tuning range,the signal-noise ratio,the pulse duration,the output power and single pulse energy have a little fluctuation because that the gain of the EDF changes with the wavelength.It used the reflection-type Bragg grating fiber to produce a singlewavelength,nanosecond pulse duration fiber laser.When the pump power is 400 mW.The laser generates single-wavelength spectrum which has a 0.4nm(the full width at half maximum)bandwidth central at 1569.4nm.With a 700 ns rectangular pulse duration,the single pulse energy is 317.57 nJ.The innovation of this thesis is using a manual tunable filter to realize singlewavelength mode-locked output.The laser keeps stable mode locking status,the centerwavelength in the range from 1523.4nm to 1575 nm.It is more 10 nanometers wide than what is currently reported.
Keywords/Search Tags:passively mode-locked, nonlinear optical loop mirror(NOLM), dissipative soliton resonance(DSR), single-wavelength, tunable laser
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