Infrared Luminescence And Optical Amplification Of Bismuth-doped Borate And Silicate Glasses

The rapid development of information society requires the continuous improvement of data transportation capacity of optical communication Internet.It is an attractive way to increase the transferring capacity by increasing the channel number of the system.Since the channel number is determined by the gain bandwidth of fiber amplifier,the wider the gain bandwidth,the more the channel number.Considerable efforts have been devoted to the achievement of broadband amplification by choosing rare-earth(e.g.Pr³⁺,Tm³⁺or Er₃₊)doped fiber amplifiers(REDFA).Unfortunately,the application bandwidths of REDFAs are hardly beyond 100nm because the f-f transitions of rare earth ions are confined in the inner-shell, which are insensitive to local environmental.Fiber Raman amplifiers can overcome these drawbacks and realize the broadband amplification.However,they require multi-wavelength pumping schemes,high-power consumption and more complicated structures.In the current status of WDM system,there are some optical telecommunication waveband in the range of 1.2～1.6/μm which optical amplification can not be realized by REDFAs.If optical amplification can be realized by a single broadband fiber amplifier in all optical telecommunication waveband from 1.2μm to 1.6μm,a new revolution can no doubt be anticipated in the future data transportation system.In order to fabricate the new super-broadband optical amplification devices,it is essential to explore the luminescence materials especially covering 1.2～1.6μm region.With some certain excitation,bismuth-doped glasses show ultra-broadband luminescence covering 1000～1700nm wavelength region.The full width at half maximum of this infrared luminescence is over 200nm and the fluorescence lifetime is about hundred microseconds. These properties indicate that bismuth-doped glasses may be a promising optical amplification gain medium.In this thesis,we synthesize a sort of Bi-doped borate and borosilicate glasses and the corresponding infrared luminescence is studied.Upon the excitation of 808nm laser diode,the bismuth activated glass samples can emit the fluorescence peaking at 1300nm with both broadband and long lifetime feature.Main achieved results are listed as follow:1,No apparent infrared luminescence is observed in the SrO-B₂O₃ and BaO-B₂O₃ prepared in air,while glasses prepared in reducing atmosphere exhibit a broadband infrared luminescence peaking at 1300 nm with a full width at half maximum(FWHM)of about 200nm when excited by an 808nm laser diode.A mechanism was proposed to explain the observed phenomena.The presence of low valence bismuth,probably Bi⁺,is responsible for the broadband infrared emission.2,The luminescence peaking at 780nm and 1300nm is observed in Bi-doped sodium borosilicate glasses with 468nm excitation.The luminescence intensity at 780nm and 1300nm is firstly increasing but later decreasing as the composition of glass changed.3,We also observed the emission at 1300nm in Bi-doped sodium borosilicate glasses excited by 808nm LD.Based on the observation that there are similar variety of luminescence intensity at 780nm and 1300nm when the content of B₂O₃ increases,we can draw a conclusion that the luminescence centers of 780nm and 1300nm are the same,namely,Bi⁺.4,We optimize the composition of Bi-doped sodium borate silicate glass and the change in optical signal was measured with 808nm LD excitation.An ASE spectrum verifies that the glass sample realizes the optical amplification.Broadband amplification indicates that the Bi-doped sodium borate silicate glass has potential applications in broadband optical fiber amplifiers and tunable lasers.