Research On S-band Fiber Amplifier And 0.8、2.3 μm Laser Based On Thulium-doped Fluorotellurite Fiber

With the rapid development of mobile Internet,Internet of Things,cloud computing,high-definition video,the world’s network data traffic has increased sharply.However,for the single-mode optical fiber transmission system based on WDM technology,its operating band is mainly C+L band,due to the amplification of noise and Kerr nonlinear effect,its transmission capacity is difficult to continue to increase.Therefore,the contradiction between the weak growth of optical fiber transmission capacity and the rapid growth of network data traffic will lead to the problem of"capacity crisis".The wide band optical fiber transmission technology is an effective solution to the above problems.For example,the working band of the single-mode optical fiber transmission system is expanded from the current C+L band to the S-band（1460～1530 nm）,and even wider bands,which can increase the transmission capacity several times more.Broadband optical amplification technology is the core technology to realize the wide band optical fiber transmission system.At present,S-band fiber amplifiers based on Tm³⁺-doped fluoride fiber have become mature,but their operating wavelength range does not fully cover the S-band,and their gain and saturation output power are slight low,and their noise figure is slight high,which affects their practical application.In the preliminary work,our research group prepared a new rare earth ion doped fluorotellurite fiber（Te O₂-Ba F₂-Y₂O₃,TBY）,which can be used to develop broadband wide and high-gain fiber amplifiers.Recently,our research group has used Er³⁺/Ce³⁺co-doped TBY glass fiber as the gain medium to achieve broadband optical amplification in C+L band,demonstrating its potential in the development of broadband fiber amplifiers.However,the broadband S-band amplifier based on Tm³⁺-doped TBY glass fiber has not been reported.During the Ph.D,the author focused research on the preparation of low-loss Tm³⁺-doped TBY glass fiber,S-band fiber amplifier and new band fiber laser,and obtained the following research results:1.A new type of thulium-doped TBY glass with wide band luminescence and large stimulated emission cross section is designed and prepared.In the experiment,the influence of Tm³⁺ions doping concentration on S-band luminescence intensity and spectral bandwidth is systematically studied,and the stimulated emission cross section of TBY glass in S-band is measured and calculated.The results show that its 3 d B bandwidth is 114 nm（1418-1532 nm）,which is 1.5 times that of thulium-doped fluorozirconate based glass（76 nm,1426-1502 nm）.Its maximum stimulated emission cross section is 3.34×10^-21 cm²,which is about 1.8 times that of Tm³⁺-doped fluorozirconate based glass(1.8×10^-21 cm²).2.For the first time,a new type of Tm³⁺-doped TBY glass was used as the fiber matrix material to prepare low-loss TBY glass fiber,and a high-gain fiber amplifier covering S-band was developed by using it as the gain medium.In the experiment,a Tm³⁺-doped TBY glass fiber with a length of 1.7 m and a core diameter of 7.5μm was used as the gain medium,and a dual-wavelength laser with 1400 nm and 1570 nm was used as the pump source to develop an S-band fiber amplifier with a gain greater than20 d B and a bandwidth of about 76 nm（1450-1526 nm）.The maximum signal optical output power is about 26.86 d Bm,and the noise factor in S-band is less than 6 d B.The above performance indicators are better than the existing S-band thulium doped fluorozirconate fiber amplifier.3.For the first time,the new thulium-doped TBY glass fiber is used as the gain medium to achieve the output of 815 nm fiber laser on the watt-scale.In the experiment,a new type of Tm³⁺-doped TBY glass fiber is used as the gain medium,and a dual wavelength laser of 1400 nm and 1570 nm is used as the pump source.The 815 nm thulium-doped fiber laser is developed by optimizing the gain fiber length and pump laser parameters,and its maximum output power reaches 1616 m W.The corresponding light-to-light conversion efficiency is 58.5%.These results show that TBY glass fiber can be used to develop high power 0.8μm band fiber lasers.4.Using thulium-doped TBY glass fiber as gain medium,2.3μm band laser output is realized by upconversion pumping technology.In the experiment,a 3 m TBY glass fiber with a length of 3 m was used as the gain medium and a 1400 nm and 1570 nm dual-wavelength laser was used as the pump source to achieve a 2.3μm laser output with a power of about 187 m W and a corresponding slope efficiency of 30.2%.