Studies On Mode-locked Fiber Laser Based On Two-dimensional Material

Ultrashort pulse has multiform applications in optical communication,laser medicine,laser marking.It is the most common method that using passive mode locking technology make the ultrashort pulse generate.The passively mode-locked fiber laser which we used in the experiment is adopted widely.Compared with solid laser,Fiber lasers have obvious advantages,such as compact structure,small size,low price and so on.The NPR technology is firstly used in fiber laser to realize passively mode-locked state,but it is easily influenced by environment,and self-started mode locking could not be easily achieved,These disadvantages of NPR technology lead to a two-dimensional material into the peak period,In recent years,like graphene,carbon nanotubes,and chalcogenide material are used as a saturable absorber in fiber laser,which show a high damage threshold,saturation absorption,good performance and low cost.Meanwhile,these features provide a strong support for the development of fiber lasers.This paper focuses on the experimental analysis method of two-dimensional materials in passively mode-locked fiber laser.For example,different sidebands can be achieved in fiber laser,and multi-wavelength mode-locked pulse output,and the micro operation method to realize the loss of less than 3d B in the production of saturable absorber on the mode locking device.The main research results are as follows:1.Due to the two-dimensional material attached to the optical fiber connector and D fiber are more common,so we present a new method to make the saturable absorber,which has a name with all-surface technique.This method improves the interaction efficiency of light and graphene,but also enhances the performance of the mode locking device and laser.This technique makes the two-dimensional material to wrap on the tapered region of the micro optical fiber,and the output of the mode-locked pulse is realized.Because this method has the shortcomings with high loss,serious waste of materials,and the package is not completely tight.By further investigate,we use micro operation method to achieve the good results of material loss is less than 3d B,width as low as 20?m.A new mode locking device can be realized.This mode locking device has a promoting effect on the development of new fiber lasers.2.Based on MoS₂ saturable absorber,a passively mode-locked fiber laser can achieve different spectral sidebands.By changing the polarization state of the cavity or increasing the pump power.There are three kinds of different types of sidebands.The Kelly sideband is caused by the mutual interference between soliton and dispersive wave,the dip and peak-dip sidebands are caused by the soliton period-doubling bifurcation in the cavity.At the same time,the production of the sidebands is related to the cavity length,the pulse width and the net dispersion in the cavity.3.The MoS₂ obtained by chemical vapor deposition?CVD?is transferred onto a microfiber,which is used in the ring fiber laser with a polarization-dependent isolator?PD-ISO?.The single-,dual-and triple-wavelength passively mode-locked pulses can be obtained with the Interaction of MoS₂ and PD-ISO.Meanwhile,it is the first demonstration of dual wavelength mode-locking operation with peak and dip sidebands.When the gain at different wavelengths reaches a balance,dual-wavelength,even multiple-wavelength lasing could be obtained.In another experiment,we only use a MoS₂-based mode locker in the fiber laser to generate four-wavelength mode-locked pulses,which is not easy to achieve,when we change the pump power and adjust the polarization controller.The mode locking device is used to overcome the low threshold damage characteristics of MoS₂ and enhances the interaction of light and MoS₂.4.The prepared microfiber-based Re S₂ SA is inserted into an erbium-doped fiber laser.because of the material two rhenium sulfide saturable absorption and three order nonlinear effect,can produce 318.5MHz harmonic mode-locked,corresponding to the 168 harmonic,which is 168 times of the fundamental frequency of 1.896 MHz.The output power varies linearly with the pump power,while the pulse interval remains unchanged.High repetition rate pulse laser which has the potential application of soliton communication and optical frequency comb.