Search results for "Physics::Optics"
showing 10 items of 1958 documents
Passive interferometric interrogation of a magnetic field sensor using an erbium doped fiber optic laser with magnetostrictive transducer
2015
Abstract An erbium doped (Er3+) fiber optic laser is proposed for magnetic field measurement. A pair of FBGs glued onto a magnetostrictive material (Terfenol-D rod) modulates the laser wavelength operation when subject to a static or a time dependent magnetic field. A passive interferometer is employed to measure the laser wavelength changes due to the applied magnetic field. A data acquisition hardware and a LabVIEW software measure three phase-shifted signals at the output coupler of the interferometer and process them using two distinct demodulation algorithms. Results show that sensitivity to varying magnetic fields can be tuned by introducing a biasing magnetic field. A maximum error o…
Polymer based tuneable photonic crystals
2007
We report on the fabrication and characterization of photonic crystal slab waveguide resonators which contain a nanostructured second-order nonlinear optical polymer. The combination of a photonic crystal resonator realized in a second-order nonlinear optical polymer allowed the detection of electro-optical modulation of light with a sub-1-V sensitivity. Furthermore we report on the synthesis of novel nonlinear optical polymers with large second-order hyperpolarizability and improved glass transition temperature. The polymer slab waveguide is micro patterned by means of electron-beam lithography and reactive ion etching. The photonic crystal slab-based resonator consisted of a square lattic…
Plasmonic-photonic hybrid cavity for tailored light-matter coupling
2010
We propose and demonstrate a hybrid cavity system in which metal nanoparticles are evanescently coupled to a dielectric photonic crystal cavity using a nanoassembly method. While the metal constituents lead to strongly localized fields, optical feedback is provided by the surrounding photonic crystal structure. The combined effect of plasmonic field enhancement and high quality factor (Q ≈ 900) opens new routes for the control of light-matter interaction at the nanoscale.
Two-dimensional photonic-crystal microwave waveguide
2003
This paper reports on the use of 2D photonic crystals to design microwave waveguides. The waveguide consists of a periodic arrangement of holes, with a square or rectangular cross section, that extends along the waveguide with a central defect defined by the absence of a hole. The theoretical analysis of such a structure is based on a biorthogonal-basis method and provides a full-vector description of the modes guided by the defect. Our results show that such a waveguide can be designed to support only one mode at any operating frequency. This mode is a polarization doublet whose dispersion is controlled by the geometrical parameters, thus permitting the design of a novel polarization-maint…
Efficient unidirectional polarization-controlled excitation of surface plasmon polaritons
2014
Efficient excitation of surface plasmon polaritons (SPPs) remains one of the most challenging issues in areas of plasmonics related to information communication technologies. In particular, combining high SPP excitation efficiency and acceptance of any polarization of incident light appeared to be impossible to attain due to the polarized nature of SPPs. Here we demonstrate plasmonic couplers that represent arrays of gap SPP resonators producing upon reflection two orthogonal phase gradients in respective linear polarizations of incident radiation. These couplers are thereby capable of efficiently converting incident radiation with arbitrary polarization into SPPs that propagate in orthogon…
Study of upconversion in highly Er-doped photonic crystal fibers through laser-transient dynamics
2014
The dynamic response after pump switch-on of a 980 nm pumped-ring laser based on an active photonic crystal fiber with an Er3+ ion concentration of ≈1020 ions cm−3 was registered. Then a numerical fitting procedure of a theoretical model was followed to the experimental values of the relaxation oscillation parameters as a function of the input pump power. Non-radiative energy-transfer mechanisms’ coefficients: homogeneous upconversion coefficient (Cup) and critical radii for upconversion (Ru) and migration (Rm) were determined. The calculated best-fit coefficients (Cup = 1.3 × 10−24 m3 s−1, Ru = 9 × 10−10 m, Rm = 13 × 10−10 m) were compared to those obtained with other steady-state an…
Near-infrared spatial solitons in heavy metal oxide A glasses
2007
We demonstrate two-dimensional spatial solitons excited by near-infrared picosecond pulses in Kerr-like heavy metal oxide glasses with a nonlinearity one order of magnitude larger than in fused silica. Solitons were obtained at 820 nm owing to the presence of multiphoton absorption, which prevented catastrophic collapse. © 2007 Optical Society of America.
Acousto-plasmonic coupling in engineered metal nanocomposites
2010
This work shows the production of self-assembled elongated nano-objects embedded in an oxide host oriented perpendicular to the substrate and their acousto-plasmonic dynamics. Electromagnetic “hot spots” are created that activate anomalous Raman vibrational modes.
Chirped fibre Bragg gratings for phased-array antennas
1997
A variable delay line for phased-array antennas based on a chirped fibre Bragg grating is demonstrated. The time delay of a microwave modulating signal is modified by scanning in wavelength a chirped grating. In this initial experiment, time delay variations up to 556 ps have been achieved using a grating of 0.4 nm bandwidth and 6 cm length and modulating in the frequency range 390 MHz-5.20 GHz.
Acoustic vibrations of embedded spherical nanoparticles
2005
Abstract A solid-matrix-embedded spherical nanoparticle has acoustic vibrational frequencies which are shifted and damped relative to modes of a free sphere. Not only the longitudinal plane wave acoustic impedances, but also the Poisson ratios of nanoparticle and matrix are important in determining the Q-factor of the “breathing” mode, for which frequencies and Q-factors with different material combinations are presented. High matrix sound speed (e.g. silica, titania, alumina, diamond) increases Q.