Experimental Research Of Luminescent Properties Of Bismuth/Erbium Co-doped Optical Fiber

With the arrival of the 5G,the data transmission capacity of the optical communications network is increasing rapidly.In order to achieve a good experience of global village interconnection,higher requirements are desired for the communication capacity and bandwidth of optical communications.The bismuth/erbium co-doped optical fiber(BEDF)reported can easily cover the O-band to L-band,which makes up for the narrow operating bandwidth(only C-and L-band)of erbium doped fiber(EDF),and is expected to play an important role in the ultrabroadband fiber amplifier in the future.However,BEDF has not yet been used commercially,and the near-infrared luminescence mechanism of bismuth is still controversial.In this thesis,the luminescent properties and mechanism of BEDF are studied systematically.The main work includes:1.The development and research status of bismuth-doped luminescent materials,including bismuth-doped crystal,glass,fiber and especially BEDF,are inducted and summarized.The remaining challenges of bismuth-doped fiber and BEDF are identified.2.The luminescent process of materials and the possible types of energy transfer are analyzed.The principle of near-infrared luminescence mechanism of EDF and bismuth doped fiber are introduced and summarized.At last,two possible optical effects and their mechanisms in the operation of optical fiber are discussed.3.The effects of temperature upon the luminescence properties of BEDF were studied.The effect of continuous temperature change on the luminescence of BEDF was firstly studied under 830 nm pumping.Then,the effects of extreme temperature change,including thermal quenching,liquid nitrogen cooling and the combined effect of them,upon the luminescence of BEDF were studied under 830 nm and 980 nm pumping,respectively.It is found that the near-infrared luminescence of BEDF had been significantly enhanced by thermal quenching with the appearance of two new luminescent centers located at?950 nm and 1230 nm.Especially,when the quenched fiber was immersed in liquid nitrogen for cooling,the luminescence from 900 to 1500 nm was further enhanced.At last,the luminescence of Er3+in BEDF and EDF under the same conditions have been studied and compared.Based on these observations and analysis,it is inferred that Bi+may be responsible for the near-infrared luminescence of bismuth.4.The effects of pump irradiation upon the luminescence of BEDF were studied.The photobleaching of bismuth active centre associated silicon(BAC-Si)in BEDF and its recovery process in different environments were studied under 830 nm pumping.It is found that the photobleaching of BAC-Si at room temperature is a partial reversible process,and the emission of BAC-Si in bleached BEDF can be significantly enhanced at liquid nitrogen temperature.It is inferred that the photobleaching of BAC-Si is related to the change of the valence state of Bi ion.At last,the photobleaching of BEDF,erbium/ytterbium co-doped fiber(EYDF)and EDF were further studied under 980 nm pumping.