Whispering gallery mode spectra of channel waveguide coupled microspheres

Evanescent coupling of light from glass channel waveguides into the whispering gallery modes of glass microspheres of radius 15µm and 100µm is studied experimentally at wavelengths near 1550nm. Fitting the positions, widths and heights of resonances in the experimental spectra to the characteristic equation for microsphere modes and to universal coupled microresonator theory, we establish sphere radius and index, identify mode numbers, and determine losses. The results provide detailed information for the design of optical devices incorporating microsphere resonators in planar lightwave circuits

Investigations of the effects of the growth of SnO₂ nanoparticles on the structural properties of glass–ceramic planar waveguides using Raman and FTIR spectroscopies

(100-x) SiO2–x SnO2 (x from 12 to 60 mol%) glass–ceramic thin films have been prepared by the sol–gel processing method, obtaining high SnO2 concentrations (up to 60 mol%) for the first time. Using an appropriate thermal process, SnO2 nanocrystals were nucleated in the glassy silica matrix, providing optical waveguides for x ≤ 30 mol%. M-line measurements were used to determine the thickness and refractive index of each film. Raman and FTIR spectroscopies, in situ high-temperature XRD and TEM data have been used to identify the initiation of crystallization (at about 900 °C for x ≤ 30 mol%). Calculations based on the low-wavenumber Raman data yield the sizes of the semi-conductor nanoparticles, which vary from 3.2 to 4.6 nm with heat-treatments varying from 900 °C to 1100 °C for SnO2 concentrations varying from 12 to 30 mol%. Raman and FTIR data have provided information on the structural evolutions of the matrix which result from the formation and the growth of the SnO2 nanocrystals

Early and late complications related to central venous catheters in hematological malignancies: a retrospective analysis of 1102 patients.

Several severe complications may be associated with the use of central venous catheters (CVC). We retrospectively evaluated on a large cohort of patients the incidence of CVC-related early and late complications. From 7/99 to 12/2005, 1102 CVC have been implanted at our Institution in 881 patients with hematological malignancies (142,202 total day number of implanted CVC). Early mechanic complications were 79 (7.2% - 0.55/1,000 days/CVC). Thirty-nine episodes of early infective complications (<1 week from CVC implant) occurred (3.5% - 0.3/1000 days/CVC): furthermore, 187 episodes of CVC-related sepsis (17% - 1.3/1000 days/CVC) were recorded. There were 29 episodes (2.6%) of symptomatic CVC-related thrombotic complications, with a median interval from CVC implant of 60 days (range 7 - 395). The rate of CVC withdrawal due to CVC-related complications was 26%. The incidence of CVC-related complications in our series is in the range reported in the literature notwithstanding cytopenia often coexisting in hematological patients

Slab optical waveguides in Er(3+)-doped tellurite glass by N(+) ion implantation at 1.5 MeV

Slab optical waveguides were fabricated in tungsten-tellurite glass doped with Er3+ ions by means of nitrogen ion implantation at 1.5 MeV. A wide range of ion doses (from 5 . 10(12) to 8 . 10(16) ions/cm(2)) was used. Optical characterization, performed by dark-line spectroscopy, revealed that the waveguides were of optical barrier type: the implanted layer exhibited a decrease of the refractive index with respect to the virgin bulk glass, while the region comprised between the sample surface and the end of the ion track acted as an optical guiding structure. It was also demonstrated that a post-implantation annealing process, performed at various temperatures on the samples implanted at higher doses, contributes to the reduction of the barrier region. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3559209