Christian Boisrobert

Experimental synthesis of fiber Bragg gratings using optical low coherence reflectometry

We apply a combination of optical low coherence reflectometry and a layer-peeling method to the synthesis of a fiber grating. The index modulation amplitude we obtain is compared with a Krug measurement result and the dc refractive index is derived from the phase measurement.

Determination of strain distribution and temperature gradient profiles from phase measurements of embedded fibre Bragg gratings

In this paper, a powerful method for measuring non-uniform strain is reviewed and extended to the measurement of temperature gradients inside an epoxy part. The sensor is an embedded fibre Bragg grating and the method is based on the measurements of the grating phase obtained by combining optical low coherence interferometry and an inverse scattering algorithm. This method has a great potential and for the first time experimental results obtained for both strain distribution and temperature gradient are presented. By applying a tensile test, strain distribution measurements are first compared with finite element simulations to validate previous published results. Second, original temperature gradient measurements in a solid body are shown. The results are in good accordance with reference measurements achieved with thermocouples incorporated into the body.

Local characterization of fiber-Bragg gratings through combined use of low-coherence interferometry and a layer-peeling algorithm

The technique presented here allows us to obtain an accurate determination of the refractive index modulation amplitude, the mean effective index, and the chirp of fiber-Bragg gratings. A layer-peeling algorithm is used to extract this information from low-coherence interferometry measurements. Finally, we present a systematic study over 10 uniform and chirped gratings to proof the reliability and accuracy of this technique.

Accurate low-coherence interferometric relative group delay and reflectance measurements: characterization of a free-space optics multiplexer/demultiplexer

In this paper, we present more results obtained on fibre Bragg gratings submitted to Round Robin tests and compare them with those obtained at NIST. We confirm that the reflectance and the relative group delay can be accurately measured with optical low-coherence interferometry. Then, complete characterization of the reflectance and group delay of a free-space optics multiplexer/demultiplexer is performed. We show the similarity of the response of the different channels.

A method to retrieve optical and geometrical characteristics of three layer waveguides from m-lines measurements

We consider three layer optical waveguides and present a method to measure simultaneously the refractive index and the thickness of each layer with m-lines spectroscopy. We establish the three layer waveguide modal dispersion equations and describe a numerical method to solve these equations. The accuracy of the method is evaluated by numerical simulations with noisy data and experimentally demonstrated using a PZT thin film placed between two ZnO layers.

Wet Chemical Etching of Pb(ZrTi)O 3 Ferroelectric Thin Films for Optical Waveguide Application

In order to develop optical waveguide structures using Pb(ZrTi)O 3 ferroelectric thin films, chemical solution deposition and spin-coating on glass substrates were studied. Classical photolithography and wet chemical etching method were applied for the realization of linear and Mach-Zehnder type waveguide structures, having a width of up to 100 w m and a irregularity of the border in the 1 w m region for an overall length of 20 mm. Optical characterization allows to qualify the ferroelectric material in terms of use for telecommunication applications, coupling of laser light by the M-lines technique allows to study light propagation and the related propagation losses.

Accelerated aging and life tests of optical fibers

The reliability of the network optical fibers is a critical issue for telecommunications. New investigations methods have been developed within a cooperative program supported by France Telecom. They include low coherence interferometry and optical near field microscopy in association with classical analysis tools such as Scanning Electron Microscopy and Shear Force Microscopy. One aim of the study is the localization and the characterization of the defects from which failure originates. The aging effect has been investigated in silica fibers immersed in desionized water at 65 °C and 85 °C for different times : from 3 to 12 months

Local and Spectral Characterization of Optical Fibers and Fiber Bragg Gratings with Low Coherence Interferometry

Abstract In this article, we describe local and spectral characterization of fibers and integrated optical components using low coherence interferometry. Chromatic dispersion and group birefringence measurements of erbium-doped fibers or photonic crystal fibers are presented, as well as local characterization of fiber Bragg gratings which allows the determination of strain and profile temperature gradient inside a material.

Optical characterization of photonic crystal fibers by optical low-coherence reflectometry and scanning near field optical microscopy

We present the structure of photonic crystal fibers and give a characterization results in birefringence and chromatic dispersion using scanning near field optical microscopy and low coherence interferometry.

OLCR characterization of a free space optics DWDM

Recent advances in DWDM system designs have led to a significant increase in the number of wavelengths in a single fiber. As network architects start to apply DWDM to regional and metro networks high performance characteristics for mux/demux (narrow and gaussian passband, weak insertion and polarization-dependent loss, low group delay responses,...) are needed. Accurate measurements of these characteristics become also necessary. In this paper, we focus on the determination of the passband and group delay of a free space optics DWDM and show that the optical low-coherence reflectometry is an efficient method for this kind of measurement.