Search

We report on a theoretical and experimental investigation of the optical Kerr effect in the evanescent field of silica nanofibers immersed in several highly nonlinear liquids such as ethanol, acetone and water and we further compare them with air cladding. We provide formula of the effective nonlinear coefficients including the contribution of the nanofiber silica core and of the evanescent field for varying nanofiber diameter and for different surrounding media. [ABSTRACT FROM AUTHOR]

The interaction of the adiabatically tapered photonic crystal fiber fundamental mode with a thin-film absorbing coating, deposited on a surface of a taper waist, on transmission of a tapered fiber is studied. Examples of using this interaction in refractive index sensors and for detection of an adsorption layer with ammonia molecules upon contact of the absorbing coating with a liquid medium are presented. It is obtained that a pronounced sensory effect occurs in the case of a resonant coupling between the fundamental fiber mode and cladding modes localized between photonic crystal fiber air channels and the absorbing coating. [ABSTRACT FROM AUTHOR]

We present a non-destructive and non-invasive imaging spectroscopic technique with a high spatial and spectral resolution based on the detection of the Rayleigh scattering field radiated out of a centimetric length and micrometric size optical waveguide in operation. [ABSTRACT FROM AUTHOR]

We used Brillouin scattering in silica nanofiber to demonstrate a microNewton force sensor having weak optical losses and using only one access of the nanofiber. The measurements are in good agreement with the theoretical model. [ABSTRACT FROM AUTHOR]

Optical micro/nanofiber, with diameter close to the wavelength of the waveguided light, leaves a considerably large fractional evanescent fields for coupling with low-dimensional functional nanostructures. Here I introduce our works on 4micro/nanofiber-coupled low-dimensional structures for nanophotonic applications including gas sensing and ultrashort pulse measurement. [ABSTRACT FROM AUTHOR]

A new all fibre, and low transmission loss, digital optical strain sensor is proposed. This sensor behaves as a Coaxial Mach-Zehnder interferometer. Special depressed cladding single-mode fibre DCF was tapered down to the micrometer scale presenting FSR in the nm range. The sensor is modelled to probe up to ± 0.2% strain when under expansive or compression stresses, returning 20 optical Power Transfer Turning Points (PTTP) at 1575 nm transmitted wavelength. [ABSTRACT FROM AUTHOR]

We report on a method for the characterization of optical absorption in semiconductors at photon energies below the bandgap energy. We use intensity dependent deflection spectroscopy to measure spatially resolved the optical absorption and to separate the occurring absorption mechanisms. To this end, we take advantage of the different intensity scaling of these mechanisms and extract the material parameters by fitting the intensity dependent absorption to a physical model. Our method enables a simple but sufficient determination of crucial optical loss properties (e.g. impurity related absorption and two-photon absorption) in various semiconductor systems, e.g. substrates for optical components or solar cells. [ABSTRACT FROM AUTHOR]

In this paper, we show picometer-order mechnical displacmment measurements using a heterodyne interferometer with a phase-locked loop (PLL). A heterodyne light source for the interferometer is implemented with a frequency stabilized HeNe laser and two acousto-optic modulators. A real time phase measurement is performed by the PLL, whose software is programmed in a field-programmable gate array (FPGA). A stiff parallel spring stage combined with a high-voltage piezoelectric actuator is used to generate picometer-order mechanical motion. With the above implementations, mechanical displacement of 10 picometer or less can be measured. [ABSTRACT FROM AUTHOR]

Microsphere-assisted microscopy is a new imaging technique which allows the diffraction limit to be overcome using transparent microspheres. It makes it possible to reach a resolution of up to 100 nm in air while being label-free and full-field. An overview of the imaging technique is presented showing the influence of the photonic jet on the image nature and the unconventional behaviour of the magnification factor. Moreover, interferometry through microspheres is demonstrated for the 3D reconstruction of nanoelements. [ABSTRACT FROM AUTHOR]

Two disruptive space telescope concepts are being designed and developed at the University of Arizona; these are the 20-meter OASIS (Orbiting Astronomical Satellite for Investigating Stellar Systems) and 8.5-meter Nautilus. OASIS combines break-through inflatable aperture and adaptive optics techniques to realize the dream of a 20+ meter class spaceborne terahertz/far-infrared telescope. In the Nautilus visible/near-infrared telescope concept, conventional primary mirrors are replaced by an ~8.5-meter MODE (Multi-order diffractive engineered) lens with 10 times lower areal density and up to 100 times lower mis-alignment sensitivity over traditional systems, enabling large-diameter optical space telescopes. The OASIS and Nautilus concepts have the potential to greatly reduce mission costs and risks compared to the current state of the art. [ABSTRACT FROM AUTHOR]

Many nanophotonic devices rely on the excitation of photonic resonances to enhance light-matter interaction. The understanding of the resonances is therefore of a key importance to facilitate the design of such devices. These resonances may be analyzed by use of the quasi-normal mode (QNM) theory. Here, we illustrate how QNM analysis may help study and design resonant nanophotonic devices. We will in particular use the QNM expansion of far-field quantities based on Riesz projection to design optical antennas. [ABSTRACT FROM AUTHOR]

We discuss an approach for modal expansion of optical far-field quantities based on quasinormal modes (QNMs). The issue of the exponential divergence of QNMs is circumvented by contour integration of the far-field quantities involving resonance poles with negative and positive imaginary parts. A numerical realization of the approach is demonstrated by convergence studies for a nanophotonic system. [ABSTRACT FROM AUTHOR]