Broadband infrared luminescence from bismuth-doped germanium oxide glasses prepared by a conventional melting-quenching technique was discovered. The absorption spectrum of the glasses covered a wide range from the visible to the near-infrared wavelength regions and consisted of five broad peaks below 370, 500, 700, 800, and 1000 nm. The fluorescence spectrum exhibited broadband characteristics (FWHM) greater than 300 nm with a maximum at 1300 nm pumped by an 808-nm laser. The fluorescence lifetime at room temperature decreased with increasing Bi2O3 concentration in the glass. Codoping of aluminum and bismuth was indispensable for the broadband infrared luminescence in GeO2:Bi, Al glass.

Near-infrared broadband emission from bismuth-tantalum-codoped germanium oxide glasses was observed at room temperature when the glasses were pumped by an 808 nm laser diode. The emission band covered the O, E, S, C, and L bands (1260-1625 nm), with a maximum peak at approximately 1310 nm, a FWHM broader than 400 nm, and a lifetime longer than 200 micros. The observed broadband luminescence was attributed to bismuth clusters in the glasses. Bismuth-tantalum-codoped germanium oxide glass might be promising as amplification media for broadly tunable lasers and wideband amplifiers in optical communications.

The creation of complex three-dimensional (3D) microfluidic systems has attracted significant attention from both scientific and applied research communities. However, it is still a formidable challenge to build 3D microfluidic structures with arbitrary configurations using conventional planar lithographic fabrication methods. Here, we demonstrate rapid fabrication of high-aspect-ratio microfluidic channels with various 3D configurations in glass substrates by femtosecond laser direct writing. Based on this approach, we demonstrate a 3D passive microfluidic mixer and characterize its functionalities. This technology will enable rapid construction of complex 3D microfluidic devices for a wide array of lab-on-a-chip applications.

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We report on controllable production of nanostructures embedded in a porous glass substrate by femtosecond laser direct writing. We show that a hollow nano-void with a lateral size of ~40 nm and an axial size of ~1500 nm can be achieved by manipulating the peak intensity and polarization of the writing laser beam. Our finding enables direct construction of 3D nanofluidics inside glass.

We report on the fabrication of nanofluidic channels directly buried in silicate glass with transverse widths down to less than 50 nm using three-dimensional (3D) femtosecond laser direct writing. Using this technique, integrated micro-nanofluidic systems have been produced by simultaneously writing micro- and nanofluidic channels arranged into various 3D configurations in glass substrates. The fabricated micro- and nanofluidic systems have been used to demonstrate DNA analysis, e.g. stretching of DNA molecules. Our technique offers new opportunities to develop novel 3D micro-nanofluidic systems for a variety of lab-on-a-chip applications.

We show that Ce(3+) can be an efficient sensitizer for Yb(3+) in the host lattice of yttrium aluminum garnet (YAG). With blue-light excitation to induce the 4f-->5d transition of Ce(3+), characteristic near-IR emission of Yb(3+) due to transition of (2)F(5/2)-->(2)F(7/2) peaking at 1030 nm is generated as a result of energy transfer from Ce(3+) to Yb(3+). The result of spectral evolution with temperature indicates that the efficiency of energy transfer is enhanced owing to thermal effect. This evidence implies that the phonon-assisted process participates in the downconversion of YAG: Ce(3+), Yb(3+).

The broadband emission in the 1.2~1.6mum region from Li2O-Al2O3-ZnO-SiO2 ( LAZS ) glass codoped with 0.01mol.%Cr2O3 and 1.0mol.%Bi2O3 when pumped by the 808nm laser at room temperature is not initiated from Cr4+ ions, but from bismuth, which is remarkably different from the results reported by Batchelor et al. The broad ~1300nm emission from Bi2O3-containing LAZS glasses possesses a FWHM ( Full Width at Half Maximum ) more than 250nm and a fluorescent lifetime longer than 500mus when excited by the 808nm laser. These glasses might have the potential applications in the broadly tunable lasers and the broadband fiber amplifiers.