Comparative Performance Analysis of Femtosecond-Laser-Written Diode-Pumped Pr:LiLuF4 Visible Waveguide Lasers

In this work, we present the operation of a femtosecond-laser-written diode-pumped visible waveguide laser based on praseodymium-doped lithium lutetium fluoride. The refractive index modification induced by the femtosecond laser in the crystal exhibits an anisotropic behavior, thus enabling the fabrication of different types of waveguides from single-track structures to stress-induced waveguides and depressed cladding structures. All the waveguides were characterized by realizing transmission measurements and the waveguide design was optimized to obtain extremely low propagation losses, equal to 0.12 dB/cm. Lasing has been achieved at 604 nm and 721 nm from different waveguides. In addition, stable continuous-wave lasing at 698 nm has been obtained in a depressed cladding waveguide. This wavelength corresponds to the one needed for the transition of the atomic clock based on the neutral strontium atom. In the end, we report the observation of laser emission at 645 nm from a depressed cladding waveguide

Ablation of nanoparticles and efficient harmonic generation using a 1-kHz laser

Author name used in this publication: D. Y. Lei2013-2014 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Femtosecond Laser Mass Spectrometry and High Harmonic Spectroscopy of Xylene Isomers

Structural isomers, molecules having the same chemical formula but with atoms bonded in different order, are hard to identify using conventional spectroscopy and mass spectrometry. They exhibit virtually indistinguishable mass spectra when ionized by electrons. Laser mass spectrometry based on photoionization of the isomers has emerged as a promising alternative but requires shaped ultrafast laser pulses. Here we use transform limited femtosecond pulses to distinguish the isomers using two methods. First, we probe doubly charged parent ions with circularly polarized light. We show that the yield of doubly charged ortho-xylene decreases while para-xylene increases over a range of laser intensities when the laser polarization is changed from linear to circular. Second, we probe high harmonic generation from randomly oriented isomer molecules subjected to an intense laser field. We show that the yield of high-order harmonics varies with the positioning of the methyl group in xylene isomers (ortho-, para- and meta-) and is due to differences in the strength of tunnel ionization and the overlap between the angular peaks of ionization and photo-recombination

Search for W~1Z~2\widetilde{W}_1\widetilde{Z}_2 Production via Trilepton Final States in ppˉp\bar{p} collisions at s=1.8\sqrt{s}=1.8 TeV

We have searched for associated production of the lightest chargino, $\widetilde{W}_1$, and next-to-lightest neutralino, $\widetilde{Z}_2$, of the Minimal Supersymmetric Standard Model in $p\bar{p}$ collisions at \mbox{$\sqrt{s}$ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron collider. Data corresponding to an integrated luminosity of 12.5$\pm 0.7$ \ipb were examined for events containing three isolated leptons. No evidence for $\widetilde{W}_1\widetilde{Z}_2$ pair production was found. Limits on $\sigma(\widetilde{W}_1\widetilde{Z}_2)$Br$(\widetilde{W}_1\to l\nu\widetilde{Z}_1)$Br$(\widetilde{Z}_2\to l\bar{l}\widetilde{Z}_1)$ are presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted to Physical Review Letters. Replace comments - Had to resumbmit version with EPSF directive

Roadmap on spatiotemporal light fields

Spatiotemporal sculpturing of light pulse with ultimately sophisticated structures represents the holy grail of the human everlasting pursue of ultrafast information transmission and processing as well as ultra-intense energy concentration and extraction. It also holds the key to unlock new extraordinary fundamental physical effects. Traditionally, spatiotemporal light pulses are always treated as spatiotemporally separable wave packet as solution of the Maxwell's equations. In the past decade, however, more generalized forms of spatiotemporally nonseparable solution started to emerge with growing importance for their striking physical effects. This roadmap intends to highlight the recent advances in the creation and control of increasingly complex spatiotemporally sculptured pulses, from spatiotemporally separable to complex nonseparable states, with diverse geometric and topological structures, presenting a bird's eye viewpoint on the zoology of spatiotemporal light fields and the outlook of future trends and open challenges.Comment: This is the version of the article before peer review or editing, as submitted by an author to Journal of Optics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from i

Search for Diphoton Events with Large Missing Transverse Energy in proton-antiproton collisions at sqrt(s) = 1.8 TeV

A search for signals of new physics has been carried out in the channel p pbar -> gamma gamma + ETmiss. This signature is expected in various recently proposed supersymmetric (SUSY) models. We observe 842 events with two photons having transverse momentum ET(g) > 12 GeV and pseudorapidity |eta(g)| < 1.1. Of these, none have missing transverse energy (ETmiss) in excess of 25 GeV. The distribution of ETmiss is consistent with that of the expected background. We therefore set limits on production cross sections for selectron, sneutrino and neutralino pairs, decaying into photons. The limits range from about 400 fb to 1 pb depending on the sparticle masses. A general limit of 185 fb (95% C.L.) is set on sigma.B(pbar p -> gamma gamma ETmiss + X) where ET(g) > 12 GeV, |eta(g)| 25 GeV.Comment: 6 pp, LaTeX, 2 postscript figures. Submitted to Physical Review Letter

Search for Squarks and Gluinos in Single-Photon Events with Jets and Large Missing Transverse Energy in ppbar Collisions at SQRT(S)=1.8 TeV

We search for physics beyond the standard model using events with a photon, two or more hadronic jets, and an apparent imbalance in transverse energy, in $p\bar{p}$ collisions at the Fermilab Tevatron at $\sqrt{s}=1.8$ TeV. Such events are predicted for production of supersymmetric particles. No excess is observed beyond expected background. For the parameter space of the minimal supersymmetric standard model with branching fraction $B(\tilde\chi^0_2 \to \gamma\tilde\chi^0_1) = 1$ and $m_{\tilde\chi^0_2}-m_{\tilde\chi^0_1}>20$ GeV, we obtain a 95% confidence level lower limit of 310 GeV for the masses of squarks and gluinos, where their masses are assumed equal.Comment: 6 pages, 3 figures, submitted to Phys. Rev. Letters, fixed one referenc

Characteristics of in situ oral biofilm after 2 and 4 days of evolution

PI11/01383 from Carlos III Institute of Health (General Division of Evaluation and Research Promotion, Madrid, Spain), which is integrated in National Plan of Research, Development and Innovation (PN I+D+I 2008-2011). European Regional Development Fund (ERDF 2007-2013)