Study On S And C+L Band ASE Light Sources And Tunable Lasers Based On Tm³⁺,Er³⁺ Fluorotellurite Glass Fiber

Tellurite glass fiber has the advantages of wide optical transmission window,large nonlinear coefficient,low phonon energy,high rare earth doping concentration,good thermal stability and chemical stability.It is used in the development of S-band,C+L band fiber amplifiers and broadband supercontinum light sources,and has been applied in optical communication,optical sensing and other fields.For the S-band fiber amplifiers,Tm³⁺-doped tellurite glass fiber can be used as the gain medium to achieve S-band optical amplification,but the gain reported is small.For the C+L band fiber amplifiers,the Er³⁺-doped tellurite glass fiber as the gain medium has been realized and applied,but the working wavelength does not cover the whole L-band.In the previous work,our group prepared Er³⁺-doped tellurite microstructure fiber,and used it as the gain medium to achieve light amplification covering the whole C+L band.Recently,our group designed and prepared Tm³⁺-doped fluorotellurite glass fiber（70Te O₂-20Ba F₂-10Y₂O₃,TBY）,using it as a gain medium to achieve light amplification covering the whole S-band.The above results show that the rare earth doped tellurite glass fiber has a wide gain bandwidth.Hence,fiber amplifiers,S-band and C+Lband wideband ASE light sources and tunable lasers can be realized.However,wideband ASE light sources and tunable lasers based on rare earth doped TBY glass fiber have not been reported.During the doctoral study,the author researched on TBY glass fiber fusion spliced technology,S-band,C+L-band ASE sources and tunable lasers,and obtained the following research results:（1）The low-loss fusion spliced between Er³⁺-doped TBY glass fiber and silicon fiber was realized by using the improved low-temperature fusing technology.L-band and C+L band all-fiber ASE light sources were developed experimentally.In the experiment,TBY glass fiber with Er³⁺-doping concentration of～4000 ppm and the core diameter of 8.5μm was used as the gain medium,1480 nm laser was used as the pump source,and the all-fiber ASE light source covering the whole L-band was realized by optimizing the fiber length and pump power.The 10 d B bandwidth is～65.6 nm（1560.1～1625.7 nm）,and the maximum power is～69.2 mW.Further,the C+L band all-fiber ASE light source is realized by bidirectional pumping,with a 10 d B bandwidth of 80.8 nm（1529.9～1620.7 nm）and an output power of～207 mW.（2）Using Tm³⁺-doped TBY glass fiber as gain medium,an all-fiber ASE light source covering the whole S-band realized for the first time.In the experiment,TBY glass fiber with Tm³⁺-doping concentration of～4000 ppm and core diameter of～8μm was used as the gain medium,and 1400 nm and 1570 nm laser were used as the pump source.By optimizing parameters such as fiber length and pump power achieved an all-fiber ASE light source covering the whole S-band with a 10 d B bandwidth of 81 nm（1449～1530 nm）and a maximum output power of 45.6 mW.（3）Using Tm³⁺-doped TBY glass fiber as gain medium,the S-band tunable fiber laser has been experimentally developed for the first time.In the experiment,a tunable fiber laser with working wavelength covering 1460～1526 nm was developed by using a ring cavity,a 1400/1570 nm dual-wavelength laser as the pump source,a tunable optical filter as the wavelength tuning element,and a Tm³⁺-doped TBY fiber as the gain medium.The maximum output power is～22 mW.