Investigation Of Photoluminescence Characteristics And Microsphere Lasing Devices Based On Rare-earth Ions Doped Fluorozirconate Glass

As one of significant fluoride glasses,fluorozirconate glass has low-phonon energy circa580 cm^-1,compared with 1200 cm^-1 of the conventional silica glass.The low phonon energy is beneficial to reduce the non radiative relaxation rate,so as to improve the transmission range and the photoluminescence efficiency.ZBLAN(Zr F₄-Ba F₂-La F₃-Al F₃-Na F)glass,the traditional fluorozirconate glass has been widely used in S-band fiber amplifiers and mid-infrared lasers(beyond 2.7?m)due to its excellent optical properties such as low phonon energy,high tramisssion in mid-IR region,good solubility for rare-earth ions etc.However,ZBLAN glass still has some serious defect,such as chemical unstability and low glass transition temperature,which limits the applications.As a novel optical glass material,Zr F₄-Ba F₂-YF₃-Al F₃(ZBYA)fluorozirconate glass has much more stable chemical properties compared with that of ZBLAN fluorozirconate glass,it therefore can be a good candidate as laser gain glass material.At present,ZBYA glass research has mostly focused on the photoluminescence properties over the mid-infrared waveband(?2.7?m)and no investigation has been reported in lasing applications.In this thesis,ZBYA glass microspheres are fabricated by a CO₂ laser,and the near-infrared laser based on WGM theory are presented for the first time using rare-earth ions doped ZBYA fluorozirconate glasses as the gain medium.The main research contents and innovative results of the thesis are listed as follows:To investigate the photoluminescence characteristics of ZBYA fluorozirconate glasses,ZBYA glasses were prepared and characterized by doping with a number of rare earth ions,including Er³⁺ion,Ho³⁺ion single-doped and Ho³⁺/Yb³⁺,Dy³⁺/Tm³⁺ions co-doped.The absorption and emission cross-sections of different rare earth ions in ZBYA glasses were calculated.The energy level transition mechanism and energy transfer process under the conditions of single-and co-doped rare earth ions were analyzed in detail.The spectral properties of ZBYA glasses doped with different rare-earth ions in infrared band were tested respectively.The high efficiency photoluminescence in near-and mid-infrared band were achieved by selecting an appropriate pumping source.Next,series of microsphere cavity laser devices were obtained using rare-earth ions doped ZBYA glasses.ZBYA glass filaments were fabricated from the fused ZBYA glasses,and the microspheres were prepared by heating the glass filaments with CO₂ laser.The WGM lasers in microspheres were excited by tapered fiber coupling.Under the pumping of 980 nm laser,up-conversion WGM fluorescence in the visible band and dual-wavelength cascade laser at 850nm and 1.55?m bands were achieved in Er³⁺-doped ZBYA glass microspheres.Futhermore,the effects of Er³⁺ion doping concentration,microsphere size,pump power and pump wavelength on ZBYA microsphere WGM lasers were also studied.Finally,the laser properties of ZBYA glass microspheres at 2.0?m band were investigated.WGM laser outputs at 2.0?m band were realized in Tm³⁺ion single-doped,Ho³⁺ion single-doped and Tm³⁺/Ho³⁺co-doped ZBYA glass microspheres.ZBYA glass microspheres doped with Tm³⁺and Ho³⁺ions were pumped by 793 nm and 1150 nm laser respectively to achieve low threshold WGM lasers at 1.9?m and 2.08?m band.In addition,the Tm³⁺/Ho³⁺co-doped ZBYA glass microspheres were designed and prepared.Under the 793 nm laser excitation,triple-wavelength lasing at 1.5?m,1.84?m and 2.08?m band were obtained.In this thesis,the photoluminescence and laser performance characterization of ZBYA glasses doped with rare earth ions have been demonstrated experimentally.High-quality optical microsphere cavities based on ZBYA glasses were fabricated and WGM laser outputs in the near-infrared band were achieved successfully.This work has a significant role in promoting the practical application of ZBYA glass matrix materials in the laser field,and also has important reference significance for the cross-disciplinary research of optical glass materials,integrated optics and laser optics.