UV-curable glassy material for the manufacture of bulk and nano-structured elements

An ultra violet (UV) -cured glassy material with less than 30% organic residues was fabricated by the fast sol-gel method. The material presents high thermal stability, good optical quality and high adhesive strength. It is suitable for optical bonding and, for manufacture of optical elements and micro-structured optical devices. Either soft-lithography or photo-lithography may be used for manufacture of the material while its curing can be thermal (few hours) or UV (few seconds). In this work we present the technology to fabricate optical elements at scales spanning the sub-micron to centimeter range. This technology enables mass-production of optical elements at low cost

Optical bonding with fast sol-gel

We investigate here the properties of fast sol-gel for optical bonding. The precursors of the fast sol-gel material are organically modified alkoxides generating a transparent hybrid (organic-inorganic) substance with silica glass-like properties whose index of refraction can be modified by the addition of various metal-oxides. The fast sol-gel method consists of rapid fabrication of a viscous resin and its subsequent dilution for long shelf life use. This material, when used as an adhesive offers the option of either a thermal or UV curing procedure. We demonstrate a bonding strength of ~ 10 MPa when a 15 µm layer is applied between two glass elements. The bonding remained stable after an extensive -40ºC – 120ºC temperature cycling with minimal residual solvent evaporation at 150ºC. The fast sol-gel material was tested for optical bonding between silica bulks, between silica bulk and silicon wafers and as an adhesive in silica fibre couplers

Macro-scale transport of the excitation energy along a metal nanotrack: exciton-plasmon energy transfer mechanism

Presently we report (i) excited state (exciton) propagation in a metal nanotrack over macroscopic distances, along with (ii) energy transfer from the nanotrack to adsorbed dye molecules. We measured the rates of both of these processes. We concluded that the effective speed of exciton propagation along the nanotrack is about 8 × 107 cm/s, much lower than the surface plasmon propagation speed of 1.4 × 1010 cm/s. We report that the transmitted energy yield depends on the nanotrack length, with the energy emitted from the surface much lower than the transmitted energy, i.e. the excited nanotrack mainly emits in its end zone. Our model thus assumes that the limiting step in the exciton propagation is the energy transfer between the originally prepared excitons and surface plasmons, with the rate constant of about 5.7 × 107 s-1. We also conclude that the energy transfer between the nanotrack and the adsorbed dye is limited by the excited-state lifetime in the nanotrack. Indeed, the measured characteristic buildup time of the dye emission is much longer than the characteristic energy transfer time to the dye of 81 ns, and thus must be determined by the excited state lifetime in the nanotrack. Indeed, the latter is very close to the characteristic buildup time of the dye emission. The data obtained are novel and very promising for a broad range of future applications.PR Institute of Functionalized Nanomaterials NASA EPSCoR grant (NASA Cooperative Agreement) NNX15AK43A National Centre for Research Resources NIH-NCRR-G12-RR03035 NIMHD-G12-MD007583info:eu-repo/semantics/publishedVersio

NEW SOLID GLASS LASER FOR PHOTODYNAMIC THERAPY

A stable tunable solid state laser emitting around 620 nm is made of a composite glass impregnated by photostable perylimide dye. The laser was pumped with copper vapor laser and the output energy obtained was a few µJoul per pulse (repetition rate 50 Hz). No significant change in the output power was observed during several hours of operation. Higher output energies are expected. This new laser should be suitable for photodynamic therapy (PDT) and laser-induced fluorescence (LIF) diagnostics in conjunction with hematoporphyrin derivative (HPD) excited at 630 nm

SPECTROSCOPIE OF LASER DYE OXAZINE-170 AS A FUNCTION OF ENVIRONMENT AND pH

Absorption end emission spectra of Oxazine - 170, which is one of important laser dyes in the region of 600-700 nm were studied as a function of environment in water, ethanol, methanol, tetrahydrofuran, chloroform, in thin films of polymethylmethacrylate (PMMA) and sol-gel thin films, and in bulk sol-gel glass. The absorption spectra are pH sensitive and the pH dependence reveals existence of two distinct species of oxazine, a cationic form and a molecular form, extinction coefficient of the latter being about half of the former. The quantum yield of the cationic form is high while the quantum yield of the molecular form is an order of magnitude lower. Formation of dimers at high concentrations of oxazine poses a serious problem in thin films, which may be remedied by decreasing the concentration of the dye and by multiple thin film coatings. The bulk glasses show quantum efficiency dependent on conditions of preparation. These results form a frame of guidelines for a choice of optimal environment of a laser dye, whether in solutions or in a solid matrix

Two-Photon Absorption Measurements Of Fluorine-Based Molecules Using Femtosecond Z-Scan

We present 2PA spectral measurements of new fluorene-based molecules with electronwithdrawing nitro groups measured using femtosecond Z-scans and compare them to picosecond Z-scan results and 2-photon fluorescence. We observe what looks like one-photon resonance enhancement. © 2005 Optical Society of America

Two-Photon Absorption Measurements Of Fluorine-Based Molecules Using Femtosecond Z-Scan

We present 2PA spectral measurements of new fluorene-based molecules with electronwithdrawing nitro groups measured using femtosecond Z-scans and compare them to picosecond Z-scan results and 2-photon fluorescence. We observe what looks like one-photon resonance enhancement. © 2005 Optical Society of America