Search results for "Physics::Optics"
showing 10 items of 1958 documents
Polymer-metal waveguides characterization by Fourier plane leakage radiation microscopy
2007
International audience; The guiding properties of polymer waveguides on a thin gold film are investigated in the optical regime. The details of propagation in the waveguides are studied simultaneously in the object and Fourier planes, providing direct measurement of both the real and imaginary parts of the effective index of the guided mode. A fair agreement between theoretical analysis provided by the differential method and experimental leakage radiation microscopy data is shown. All these tools bring valuable information for designing and understanding such devices. (C) 2007 American Institute of Physics.
EPR characterization of erbium in glasses and glass ceramics
2020
Electron paramagnetic resonance (EPR) is a well-established spectroscopic technique for electronic structure characterization of rare-earth ion impurities in crystalline and amorphous hosts. EPR spectra of erbium-doped glass matrices and nanocomposites can provide information about local structure variations induced by changes in chemical composition or crystallization processes. Characterization possibilities of Er3+ ions in glasses and glass ceramics including direct EPR measurements, indirect investigations via secondary paramagnetic probes, and optically detected magnetic resonance techniques are considered in this article. ----/ / /---- This is the pre-print of the following article: A…
Shot-by-shot frequency calibration of CARS spectra: Application to the measurement of the collisional line shift in oxygen
1996
A technique using a Fabry-Perot interferometer has been developed to calibrate high-resolution spectra obtained by Coherent Anti-Stokes Raman Spectroscopy (CARS). This technique was used to measure simultaneously the Raman frequency and the Raman signal at each laser shot. We demonstrate the accuracy of the method by measuring theQ(15) line shifts of molecular oxygen due to collisions with oxygen and water vapour.
Compact Mach-Zehnder acousto-optic modulator
2006
The authors demonstrate a compact optical waveguide modulator based on a Mach-Zehnder interferometer driven by surface acoustic waves. The modulator was monolithically fabricated on GaAs with an active region length of approximately 15μm. It yields peak-to-peak modulation exceeding 90% of the average transmission and operation in the gigahertz frequency range.
Continuous-wave backward frequency doubling in periodically poled lithium niobate
2010
We report on backward second-harmonic-generation in bulk periodically poled congruent lithium niobate with a 3.2 microns period. A tunable continuous-wave Ti:sapphire laser allowed us exciting two resonant quasi-phase-matching orders in the backward configuration. The resonances were also resolved by temperature tuning and interpolated with standard theory to extract relevant information on the sample.
Thermo-electric detection of waveguided surface plasmon propagation
2011
International audience; The thermo-electric detection of a waveguided surface plasmon traveling along one electrode of an in-plane integrated thermocouple is demonstrated. By using a particular design of the thermocouple, the thermo-electric signal due to the losses of the plasmon mode can be separated from the non-resonant heating of the waveguide. The thermo-electric signal associated with the plasmon propagation is proportional to the power coupled into the waveguided mode and exhibits a maximum at a distance from the excitation site depending on both the heat transfer coefficient of the system and the plasmon mode damping distance.
In situ tuning of a photonic band gap with laser pulses
2008
We report on light-induced optical tuning of colloidal photonic crystals doped with gold nanoparticles (Au-nps). By resonantly exciting the Au-np surface plasmon absorption with picosecond pulses at 0.53 micron in a standard pump-probe setup, we observed permanent changes in the stop band resonance around 1.7 micron, with blue wavelength shifts as large as 30 nm and associated to a nanoparticle reshaping. Fine tuning was achieved by controlling either the pulse energy or the irradiation time.
Near-band luminescence of CdZnTe detector crystals
2012
The near-band luminescence due to both neutral donor and neutral acceptor bound excitons (D0 Ex), (A0Ex) and its phonon replicas as well as luminescence of donor-acceptor pair (DAP) and deep energy level due to undefined defect state (A band) were studied in CZT detector crystals. The near-band luminescence correlation with detector characteristics was analyzed and the results could be applied for nondestructive detector material selection. It is obtained that some parameters such as a presence and intensity of A and DAP luminescence bands, the decay kinetics in A0Ex-1LO and DAP luminescence bands, are most important characteristics for detector material characterization.
Optical investigation of the OH− groups in the LiNbO3 doped by copper
2019
Doping ions and OH− groups absorption bands spatial profiles were investigated for the case of congruent LiNbO3 single crystal grown by Czochralski technique. Doping was performed after the crystal...
Second-harmonic Generation Microscopy of Carbon Nanotubes
2012
We image an individual single-walled carbon nanotube (SWNT) by second-harmonic generation (SHG) and transmission electron microscopy and propose that SHG microscopy could be used to probe the handedness of chiral SWNTs.