Dominique Pagnoux

Fibre Bragg grating photowriting in microstructured optical fibres for refractive index measurement

We report results relating to fibre Bragg grating photowriting in two kinds of Ge-doped core microstructured optical fibre devoted to sensing applications. A cross-comparison between theoretical and experimental modal field patterns is carried out. We present the first values of the spectral sensitivity of a Bragg grating in relation to the refractive index of calibrated oils inserted into the holes.

Tilted Fiber Bragg Grating photowritten in microstructured optical fiber for improved refractive index measurement

We report what we believe to be the first Tilted short-period Fiber Bragg Grating photowritten in a microstructured optical fiber for refractive index measurement. We investigate the spectral sensitivity of Tilted Fiber Bragg Grating to refractive index liquid inserted into the holes of a multimode microstructured fiber. We measure the wavelength shift of the first four modes experimentally observed when calibrated oils are inserted into the fiber holes, and thus we determine the refractive index resolution for each of these modes. Moreover, a cross comparison between experimental and simulation results of a modal analysis is performed. Two simulation tools are used, respectively based on the localized functions method and on a finite element method. All results are in very good agreement.

Analysis of the birefringence of solid-core air-silica microstructured fibers

The origin and the behavior of the birefringence of solid-core air-silica microstructured fibers is described with the help of a simple approximate model. The first two modes of three different types of fibers are studied. Numerical results, obtained from both finite element and boundary integral methods calculations, are presented to support the validity of the model and to delineate its limits.

Azimuthal far-field analysis for the measurement of the effective cutoff wavelength in single-mode fibers/spl minus/effects of curvature, length, and index profile

The spectral analysis of the optical power transmitted through a bow tie slit rotating in the far-field pattern of a single-mode fiber provides an easy and accurate mean of determining the effective cutoff wavelength of the fiber. The principle of this technique is described. Theoretical considerations show that the ratio between the optical powers carried by the LP/sub 11/ mode and the fundamental mode, respectively, is directly related to the amplitude of two particular lines in the spectrum. The degree of coherence of the analyzed field is shown to be related to the amplitude of a third line. Owing to the sensitivity of the method, the detectable amount of the total power which is contained in the LP/sub 11/ mode is as small as 0.5%. The effects of length and curvature on the effective cutoff wavelength are measured over wide ranges for different kinds of single-mode fibers. The behavior of a quadruple-clad flattened dispersion fiber is shown to be somewhat different from that of a typical depressed cladding fiber. >

Theoretical and experimental study of loss at splices between standard single-mode fibres and Er-doped fibres versus direction

By means of a 2D beam propagation method and a very simple and reliable measurements set-up, it is shown that the loss at splices between standard single-mode fibres and Er-doped fibres does not depend on the direction of propagation of light. This conclusion contradicts several previously published assertions in which some important parameters have been neglected.

Modelling and analysis of modal effects at misaligned connections between non-identical multimode fibres

Abstract A simple theoretical characterization of modal effects at misaligned connections between non-identical graded-index fibres (hybrid connections) is proposed using rigorous analytical expressions of power transfer coefficients previously established for misaligned homogeneous connections. The characteristics of the homogeneous connection equivalent to a given misaligned hybrid connection are determined.

Fiber Bragg grating photowriting in microstructured optical fibers for sensing application based on refractive index measurement

In this paper we present results relative to Fiber Bragg Grating (FBG) photowritten in two kinds of Ge-doped microstructured optical fiber cores devoted to sensing applications. A cross-comparison between theoretical and experimental modal field patterns is carried out. We present the first values of spectral sensitivity of Bragg grating in relation to the refractive index of the substance inserted into the holes.

Measurement of fiber offsets in multimode connectors, using single-mode excitation

Abstract The measurement of the global losses of multimode connection under single-mode excitation is realized. It leads to the determination of the offset between the fibers in operating connectors. Theoretical and experimental results are in good agreement, and allow precise characterization of multimode connections.

All-normal dispersion supercontinuum generation in the near-infrared by Raman conversion in standard optical fiber

We demonstrate all-normal dispersion supercontinuum generation in the 1080 nm-1600 nm range by propagating subnanosecond pulses in a high numerical aperture standard optical fiber. The extreme saturation of the Raman gain provides a flat spectrum in the considered range, making this broadband source particularly suitable for coherent Raman spectroscopy. This unusual regime of supercontinuum generation (Raman gain saturation regime) is investigated through an experimental spectrotemporal study. The possibility of operating spectrometer-free time-coded coherent Raman spectroscopy is introduced.

Microwave assisted nanosecond CARS multiplex system

We present experimental results on microwave assisted Multiplex Coherent Anti-Stokes Raman Spectroscopy (M-CARS) measurements in liquids. The applied nanosecond electric field allows M-CARS signal enhancement and offers potentialities to remove non resonant background.