Research On Tunable Erbium-doped Fiber Lasers Based On Tungsten Disulfide Thin Film

Since the 21st century,with the continuous progress and development of optical communication technology,especially the increasing demand for high-speed communication in emerging industries such as the Internet of Things and smart cities,the use of optical fiber communication to solve the problem of high-speed transmission of huge information data has been highly recognized.Especially the use of wavelength division multiplexing（WDM）technology,further improve the utilization rate of optical communication channels.Therefore,the following requirements are put forward for multi-wavelength fiber lasers as channel light sources,which can output high side-mode rejection ratio（SMSR）,flat output wavelength power,and at the same time should be tunable and switchable.In order to achieve the above requirements,tungsten disulfide（WS₂）is selected as a frequency stabilizer in two-dimensional nano-thin film materials.Based on the existing tunable fiber filters,three novel tunable and switched erbium-doped fiber laser（EDFL）are studied and designed.These three novel EDFLs have high SMSR and good stability.The main research contents and achievements are as follows:1.A multi-wavelength EDFL based on WS₂thin film is proposed and studied.WS₂thin films can achieve multi-wavelength flat output.The laser achieves 5,9 and13 wavelength outputs with wavelength intervals of 1.38,0.70 and 0.42 nm at 250m W pump power by changing the length of the polarization-maintaining fiber（PMF）in the Lyot filter to 4,8 and 12 m.The SMSR of the laser is higher than 40 dB.2.A switchable EDFL based on reconfigurable Lyot ring filter（RLRF）is proposed and studied.WS₂films can achieve multi-wavelength flat output.Under the pump power of 300 m W,the number of wavelengths can be switched from 2 to 8 by adjusting polarization controller 1（PC1）in the RLRF.The PC2 is adjusted to realize the switching between three states with different wavelength intervals.The RLRF can achieve twice the length of PMF,a total of 12 laser state.The SMSR of the laser is higher than 42 dB.3.A switching and tunable EDFL based on reconfigurable Lyot and double Sagnac loop cascade filter（RL-DSLCF）is proposed and studied.The laser achieves single,double and triple wavelength switching by adjusting the PC in the RL-DSLCF at the pump power of 250 m W.Single and dual wavelengths are continuously tuned in the range of 10 nm;The double and triple wavelengths are tunable in the range of 10nm,and there are 10 laser states.The SMSR of the laser is higher than 48 dB.