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Er3+(/Yb3+)-doped Li3NbO4 powder were prepared by thermally sintering mixtures of Er2O3 (0.5, 1.0 mol%), Yb2O3 (0, 0.5, 1.0 mol%), Li2CO3 (48–49 mol%) and Nb2O5 (50 mol%) at 1125, 1150 and 1450 °C over the durations of 8–22 h. The crystalline phases contained in these samples were determined by using X-ray diffraction and discussed in comparison with a vapor-transport-equilibration-treated (VTE-treated) Er(2.0 mol%):LiNbO3 single crystal and ErNbO4 powder previously reported. The results show that the X-ray patterns of the rare-earth-doped samples reveal little difference each other, but large differences with those of the VTE crystal and ErNbO4 powder. The doped rare-earth ions Er3+ (and Yb3+) present in the powder as the ErNbO4 (and YbNbO4) phase(s). The possibility that the highly Er-doped LiNbO3 crystal contains Li3NbO4 precipitates is small. Optical absorption and emission studies show that the only Er-doped Li3NbO4 powder shows similar absorption and emission characteristics with the pure ErNbO4. The codopant Yb3+ ion enhances the 980-nm-upconversion emissions of Er3+ ions, results in remarkable spectral alterations at 0.98 μm region, and causes the alterations of relative absorbance and relative emission intensity of individual peaks or bands at 1.5 μm region. On the other hand, the Yb-codoping hardly affects the Er3+ energy structure and the lifetime of Er3+ ion at 1.5 μm. The measured lifetimes at 1.5 μm of Er3+ ions in the singly Er3+- and doubly Er3+/Yb3+-doped mixtures have a nearly same value of ∼ 1.5 ms. For the pure ErNbO4 powder, the lifetime is prolonged to ∼2 ms perhaps due to radiation trapping effect. [ABSTRACT FROM AUTHOR]

Multi-photon-excited thermal-correlated green and red upconversion (UC) emissions have been quantified in H o 3+ / Y b 3+ co-doped fluotellurite (BZLFT) glass phosphor under the 978 nm laser excitation. The temperature dependence of the fluorescence intensity ratio (FIR) originated from UC emissions bands centered at 550 nm and 661 nm has been verified in the range of 303-543 K. The net emission photon numbers of 5 F 4 + 5 S 2 → 5 I 8 and 5 F 5 → 5 I 8 transition emissions are up to 40.08×10 12 and 68.51×10 12 c p s in the 0.4 w t . % H o 2 O 3 -0.4 w t . % Y b 2 O 3 co-doped BZLFT case under the 6.95 W / m m 2 laser power density. Furthermore, the quantum yield (QY) and luminous flux are determined to be dependent on pumping power. When the excitation power increases 874 mW, the QY values for 550 nm and 661 nm emissions are as high as 0.94×10 -5 and 1.60×10 -5 . In addition, the high photon producing efficiency is conducive to ensuring high feedback to thermosensitive performance. The temperature thermal sensor can be manipulated steadily in medium temperature range, and the relative sensitivity reaches 0.4 % K -1 at 303 K, which is 1 order of magnitude larger than those in several rare-earth-doped materials. Efficient photon conversion ability and high temperature sensitivity indicate that the rare-earth-ion-doped fluotellurite material has a prospective application in the construction of optical temperature sensors based on the FIR technique allowing for self-referenced temperature determination.

Intense multi-peak red fluorescence and effective near-infrared (NIR) ultra-broadband emission have been observed in Pr 3+ doped ion-exchangeable aluminum germanate (NMAG) glasses. The maximum emission cross section for P 0 3→F 2 3 red emission is up to 100.58×10 -21   cm 2 , and the NIR emission corresponding to D 2 1→G 4 1 transition possesses a full-width at half-maximum (FWHM) of 210 nm. Although the obvious cross-relaxation (CR) process at high concentration causes a decrease of the quantum efficiency, the CR broadens the spectral FWHM effectively from another perspective. The admirable red fluorescence trace and the NIR single-mode transmission confirm that Pr 3+ doped NMAG glass planar waveguides can support the generation of visible fluorescence and the amplification of infrared signal. For a waveguide channel ion-exchanged in molten KNO 3 for 2 h, the single-mode field diameters at 1.55 μm are identified to be 10.4 μm in the horizontal direction and 6.5 μm in the vertical direction, implying an acceptable overlap with a standard single-mode fiber. Effective red fluorescence and broad NIR emission demonstrate that Pr 3+ doped NMAG glasses are a promising substrate in developing irradiative luminescence sources and ultra-broadband waveguide amplifiers, especially operating at the entire S-, C-, and L- bands.

In Sm(3+)-doped K(+)-Na(+) ion-exchanged aluminum germanate (NMAG) glass channel waveguide, a clear and compact red amplified spontaneous emission (ASE) trace is observed under the excitation of a 488nm Ar(+) laser. 78% photons of ASE fluorescence in visible region are demonstrated to be located in 600-730nm wavelength range. High-directivity and high-brightness ASE fluorescence of Sm(3+)-doped NMAG glass channel waveguide, which matches the excitation band of most photosensitizers (PS) currently used in photodynamic therapy (PDT) or clinical trials, has promising potential application as an excitation light source for PDT treatment.

Plasmonic or metamaterial nanostructures are usually fabricated on rigid substrate i.e. glass, silicon. Optical functionality of such kinds of nanostructures is limited by the planar surface and thus sensitive to the incident angle of light. In this work, we demonstrated that a tri-layer flexible metamaterials working at near infrared (NIR) regime can be fabricated on transparent PET substrate using flip chip transfer (FCT) technique. FCT technique is solution-free and can also be applied to fabricate other functional nanostructures device on flexible substrate. We demonstrated NIR metamaterial device can be transformed into various shapes by bending the PET substrate.