Soft glass highly nonlinear fibers have high nonlinearity and a broad transparency range, but their chromatic dispersion is far from being freely tailored until now due to the immaturity in fabrication technology. In this research, the chromatic dispersion of soft glass highly nonlinear fibers was controlled by using the complex microstructure in the cladding. A tellurite glass fiber which had a 1.8 μm core surrounded by four ring holes was fabricated. The preform was fabricated by the method of cast rod in tube and stack. The chalcogenide–tellurite glass composite fibers which had a 1.5 μm core surrounded by tellurite microstructure cladding were demonstrated. Their preform was fabricated by the method of stack and draw. In the fiber-drawing process of both types of fibers an inflation pressure of nitrogen gas was pumped into the holes of the preform to overcome the surface tension and to reshape the microstructure. The tellurite complex microstructured fiber has a chromatic dispersion much more flattened than that of step-index air-clad fiber. The chalcogenide–tellurite glass composite fibers have the zero dispersion wavelength (ZDW) in the near-infrared range. Having the ZDW in the near-infrared has not been realized before for the fibers made from chalcogenide glass. Meanwhile, the composite microstructured fiber with large holes in the cladding has the highest nonlinearity of all highly nonlinear fibers if the tapered fibers are excluded. Supercontinuum spectra covering over one octave, free of fine structures, were demonstrated by the fabricated fibers.

Er3+/Yb3+ codoped fluorophosphate glasses were prepared and their thermal stabilities, Raman spectra, absorption spectra, and fluorescence spectra were measured. It is found that proper content of NaF or PbF2 is helpful for the increase of stability against crystallization. The variation of Al(PO3)3 or NaF content in the composition affects not the maximum phonon energy but the phonon density. The introduction of PbF2 decreases the phonon energy slightly. Intense green and red upconversion luminescence was observed for the fluorophosphate glass with low phosphate content. A glass matrix for upconversion luminescence requiring neither expensive raw material nor special atmospheric conditioned preparation is provided. Infrared luminescence around 1530 nm was researched. Fluorophosphate glasses with bandwidth properties and stimulated-emission cross sections better than tellurite, germanate and silicate glasses are obtained. Through the introduction of NaF, the bandwidth properties are decreased. Through the introduction of PbF2 the gain properties are increased. On the whole, it is difficult to obtain a material with the best gain properties and bandwidth properties simultaneously. There should be a compromise between them according to the demand.

The sensitization mechanisms of Yb3+ to Tm3+ for the blue upconversion luminescence in fluorophosphate glass were studied. Two different mechanisms exist in the sensitization. One is the sequential sensitization that Tm3+ is excited from 3H6 to 1G4 through absorbing three photons transferred from Yb3+ one by one. Another is the cooperative sensitization that two Yb3+ ions form a couple cluster firstly, and then the couple cluster Yb3+ ions transfer their energy to Tm3+ and excite it to 1G4. With the increment of the concentration of Yb3+ ions, the sequential sensitization becomes weak and the cooperative sensitization becomes intense, and the transformation trend of sensitization mechanism with the increment of Yb3+ concentration can be clarified by the introduction of Tb3+ ions in the glass.

Fluorophosphate glasses with various content of Al(PO3)3 were prepared. With the increment of Al(PO3)3 content, density decreases while refractive index increases, and transition temperature, crystallization peak temperature and melt temperature increase which were suggested by differential scanning calorimetry. These glasses exhibit the best stability against crystallization with 7–9 mol% Al(PO3)3 content. Normalized Raman spectra were used to analyze structure and phonon state. The increment of Al(PO3)3 content does not affect phonon energy but results in the augment of phonon density. Absorption spectra were measured. 3H6 → 3F4 transition exhibits absorption at L band of the third communication window. Compared with the energy of Tm3+ excited states in other glass system, 3F4 energy of Tm3+ in these glasses is considerable higher and 3H4 energy is considerable lower, and it can be predicted that emission band of 3H4 → 3F4 transition is close to the amplified band of gain-shift Tm3+ doped fiber amplifier. Analyses of Judd–Ofelt theory suggest when Al(PO3)3 content is no more than 7 mol%, Judd–Ofelt parameters Ωt and the lifetime of 3H4 energy level of Tm3+ vary little with the increment of Al(PO3)3 content, and when Al(PO3)3 content is more than 7 mol%, Ω2 and Ω6 increase and radiative lifetime of 3H4 energy level of Tm3+ drops sharply with the increment of Al(PO3)3 content.

Er3+, Yb3+ and Tm3+ codoped fluorophosphate glasses emitting blue, green and red upconversion luminescence at 970 nm laser diode excitation were studied. It was shown that Tm3+ behaves as the sensitizer to Er3+ for the green upconversion luminescence through the energy transfer process: Tm3+:3H4 + Er3+:4I15/2 → Er3+:4I9/2 + Tm3+:3H6, and for the red upconversion luminescence through the energy transfer process: Tm3+:3F4 + Er3+:4I11/2 → Tm3+:3H6 + Er3+:4F9/2. Moreover, Er3+ acts as quenching center for the blue upconversion luminescence of Tm3+. The sensitization of Tm3+ to Er3+ depends on the concentration of Yb3+. The intensity of blue, green and red emissions can be changed by adjusting the concentrations of the three kinds of rare earth ions. This research may provide useful information for the development of high color and spatial resolution devices and white light simulation.

Fluorophosphate glasses codoped with Tm3+ and Yb3+ were prepared and their thermal stability, phonon states, and upconversion properties were studied. It is found that the increment of phosphate content is good for the thermal stability but increases the phonon density of states. However, the phonon density of states of these fluorophosphate glasses is very low due to the low phosphate content in their composition. The upconversion luminescence spectra were measured under excitation of 970 nm laser diode, and the intense blue (476 nm) and near infrared (794 nm) emission were simultaneous obtained at room temperature. The sensitizing mechanisms of Yb3+ to Tm3+ for blue and red emission contain both sequential and cooperative sensitization. The near infrared emission is a two-photon upconversion process. These researches suggest that when the phosphate content in the composition is low enough, fluorophosphate glass can be suitable host material of Tm3+ codoped with Yb3+ for blue and near infrared upconversion luminescence.