Preparation And Luminescent Properties Of Tellurium Quantum Dot Doped Phosphate Laser Glass And Fiber For Superbroadband Fiber Amplifier

Tellurium?Te?doped glass emits near-infrared luminescence in an exceptionally wide region of 900 1500 nm,which endows Te-doped glasses potential applications in the field of broadly tunable fiber laser and super pulse laser.However,challenges remain for the applications of Te-doped glass and fibers:?1?So far,Te-doped phosphate glasses exhibit stronger NIR luminescence than other diverse Te-doped glasse systems,such as silicate and borate glasses,yet the luminescence of Te-doped phosphate glasses is still weak compared to that of near-infrared-emitting materials doped with rare earth ions.?2?Te-doped phosphate glass suffers from insufficient physical,chemical and thermal stability and easy crystallization.?3?In Te-doped glasses,tellurium mainly exists in the form of Te nanoparticles with several hundred in diameter.The size reduction and homogeneous distribution of Te nanoparticles is still a problem.?4?Currently,there is no report concerning Te-doped phosphate fiber.In this work,we devoted to solve these scientific problems and the results are as follows: 1.We find that tellurium quantum dots are successfully incorporated into phosphate glasses and super-broad near-infrared?NIR?emission is observed.By modifying glass composition and structure topology,the homogeneity of Te quantum dots in phosphate is realized by simply one step incorporation method without further secondary thermal treatment.Moreover,we find that the codoping of alumina into the zinc ultra-phosphate lattice leads to increasing interchain crosslinking,which suppresses crystallization and increases corrosion resistance,and thermostability.The size of metallic tellurium inclusions was limited to sub-nanometric scale enabling the broadband NIR luminescence spanning 260 nm covering the second telecommunication window.The NIR emission presents a peak at ¹118 nm?under the excitation of 808 nm?with the full width at half maximu of ²70 nm and along decay lifetime up to several tens of microseconds.Under the excitation of 974 nm,no NIR emission if observed in our Te-doped phoaphate glass.The luminescence characteristics of our Te-doped phosphate glass is different from that of early reports.2.High efficiency favors the applications of luminescence materials.Here,we tried to enhance the NIR emission of Te-doped phosphate glass by optimizing the Al₂O₃,ZnO and TeO₂ concentration and modifying the micro structure of phosphate glasses,and we find that the optimal composition is 65P₂O₅-5Al₂O₃-25ZnO-5TeO₂.3.Gain materials lies at the heart of active optical fibers and devices.The thermal stability of Te-doped phosphate glasses is evaluated by subsequent heat treatment above Tg.After annealing,glasses remained visually transparent and homogeneous and no emission quenching was observed,which indicates that we can fabricate Te quantum dots doped phosphate fiber by rod-in-tube method.Subsequently,the fiber drawn at the temperature of 850? emits the similar NIR lumiscence as compared to that of Te-doped bulk glass samples,revealing that Te quantum dots doped phosphate glass is promising core materials for active fiber toward broadly tunable lasers and super pulse lasers.