Abnormal elemental redistribution in oxyfluoride glasses induced by high repetition rate femtosecond laser

We report on the elemental redistribution behavior in oxyfluoride glasses with a high repetition rate nearinfrared femtosecond laser. Elemental analysis by an electro-probe microanalyzer demonstrates that the redistributions of Ca~(2+) and Yb~(3+) ions change dramatically with pulse energy, which are quite different compared with previous reported results. Confocal fluorescence spectra of Yb~(3+) ions demonstrate that the luminescence intensity changes obviously with the elemental redistribution. The mechanism of the observed phenomenon is discussed.This observation may have potential applications in the fabrication of micro-optical devices.     

Femtosecond laser-inscribed waveguides in Nd3^＋：y3^＋：SrF2 crystals

Optical waveguides are fabricated in Nd3^＋：y3^＋：SrF2 crystals by a 1-kHz femtosecond laser using the double-line approach. Waveguides with different separations （10, 15, and 20 μm） between two consecutive optical breakdown tracks are produced, and their optical performances are explored by end-fire coupling to 780-and 532-nm lasers. Propagation loss of the waveguide with 20-pro separation is estimated. The micro- photohmlinescence and micro-Raman spectra indicate that the original fluorescence and lattice structure of the Nd3^＋：y3^＋：SrF2 crystals are well preserved in the waveguide. Therefore, the obtained waveguide structures are promising candidate for application in integrated waveguidc lasers.     

Femtosecond Laser-Written Waveguides in a Bismuth Germanate Single Crystal

We demonstrate the fabrication of symmetric waveguides in a bismuth germanate （BGO） single crystal using a double line approach by an 80Ohm [emtosecond laser. The optical attenuation of the single mode waveguide is measured to be 4.2 dB/cm at 633nm. The influence of pulse energy and focal depth on the end facet of the irradiated region is also studied. This technique is promising to fabricate buried BGO waveguide arrays used in positron emission tomography systems.