The Upconversion Fluorescence Specificity And Color Tunability Of Multi-rare-earth Ions Doped Aluminum Germinate Glasses

Multicolor and white fluorescences from rare-earth （RE） doped glasses have attractedmuch attention due to their potential applications in the field of solid-state lasers, optical datastorages and color displays. Warm background make eyes feel comfortable, and thus warmmulticolor and white fluorescences have attracted much more attention. In addition,anti-Stokes upconversion white fluorescence can not do harm to human body. Attentions havebeen paid to efficient upconversion fluorescence, which can be uesd for illumination inminimally invasive surgery. However, due to the multiphoton absorption process, theupconversion efficiency is poor, which can not reach the requirements of minimally invasivesurgery lighting. For RE doped devices with waveguide structure, optical fiber and waveguidechannel, when the near-infrared （NIR） laser light is coupled into the input end, theupconversion emission with strong directivity is generated in the device attributed to theupconversion amplified spontaneous emission process, and here we call it upconversion ASEfluorescence, which improves lighting quality.Based on this consideration, Tm³⁺/Yb³⁺codoped, Ho³⁺/Yb³⁺codoped andTm³⁺/Ho³⁺/Yb³⁺triply doped low phonon energy aluminum germanium （NMAG） glasseswere designed and synthesized, and the upconversion fluorescence spectrum was investigatedunder974nm laser excitation. The dependence of upconversion fluoresences intensity on thepumping power was described, the color coordinates and color temperature of theTm³⁺/Ho³⁺/Yb³⁺sample were calculated, and the dependence of color coordinates on thepumping power was studied. In addition, the ion-exchange channe waveguide was fabricatedin Tm³⁺/Yb³⁺codoped、Ho³⁺/Yb³⁺codoped and Tm³⁺/Ho³⁺/Yb³⁺triply doped NMAG glassessurface prepared, and the special character of upconversion ASE fluorescence wasinvestigated, laying the foundation for high-quality lighting in minimally invasive surgery.The followings are results this work achieved:1. Tm³⁺/Ho³⁺/Yb³⁺triply doped NMAG glasses have been synthesized and characterized.Efficient three-photon blue upconversion luminescence of Tm³⁺and two-photon green and red upconversion fluorescences of Ho³⁺have been observed, and the strong red emission ofHo³⁺, which is more than eight times higher than that of the green one, is desirable inachieving high color rendering index. By varying the intensity ratios among the upconversionemission bands, the fluorescence can be tuned to various white color lights. With increasingexcitation power, the color coordinates of the complex upconversion luminescence are drawnalong the lower left direction.2. K+-Na+ion-exchanged channel waveguide amplifiers have been fabricated inTm³⁺/Yb³⁺codoped, Ho³⁺/Yb³⁺codoped and Tm³⁺/Ho³⁺/Yb³⁺triply doped NMAG glasses.Under high-power excitation of the980nm wavelength laser diode, a high-density blue, greenand white transmission trace was achieved in Tm³⁺/Yb³⁺codoped, Ho³⁺/Yb³⁺codoped andTm³⁺/Ho³⁺/Yb³⁺triply doped NMAG glass waveguide channel. An optical fiber wasconnected to the waveguide channel, and a high-brightness white light spot was observedfrom the output end of the fiber. The fluorescent colors were diverse and mainly locatedwithin the white region under various pumping powers.