Search results for "Physics::Optics"
showing 10 items of 1958 documents
Uniform fibre Bragg gratings with an embedded perturbed section for multiple applications
1999
The interest in fibre Bragg gratings has been increased with the development of flexible fabrication techniques which are able to make gratings with any non-uniform characteristic (chirped, apodised, sampled, phase-shifted, etc.) required for an specific application [1].
Effective length of short Fabry-Perot cavity formed by uniform fiber Bragg gratings
2009
In this paper, we describe the properties of Fabry-Perot fiber cavity formed by two fiber Bragg gratings in terms of the grating effective length. We show that the grating effective length is determined by the group delay of the grating, which depends on its diffraction efficiency and physical length. We present a simple analytical formula for calculation of the effective length of the uniform fiber Bragg grating and the frequency separation between consecutive resonances of a Fabry-Perot cavity. Experimental results on the cavity transmission spectra for different values of the gratings' reflectivity support the presented theory.
Tunable Dispersion Compensator Based on a Fiber Bragg Grating Written in a Tapered Fiber
2004
We report a novel dispersion tunable device for first-order dispersion compensation. It is based on a fiber Bragg grating written in a tapered fiber with a specific profile. The taper profile allows tuning the dispersion of the grating by stretching the fiber while the linearity of the group delay is preserved. A device with 0.8 nm of useful bandwidth and dispersion value tunable over more than 400 ps/nm is reported.
In-fiber Fabry-Perot refractometer assisted by a long-period grating
2010
We present an optical fiber refractometer based on a Fabry-Perot interferometer defined by two fiber Bragg gratings and an intracavity long-period grating that makes the light confined in the resonator interact with the surrounding medium. The external refractive index is monitored by the resonant frequencies of the Fabry-Perot interferometer, which can be measured either in transmission or in reflection. In this first experiment, wavelength shifts measured with a resolution of 0.1 pm have allowed one to establish a refractive index detection limit of 2.1x10(-5).
Radiation hardening of FBG in harsh environments
2014
International audience; The difficulties encountered in the implementation of a temperature or strain sensor based on Fiber Bragg Grating in a harsh radiative environment are introduced. We present the choices made to select both a radiation-resistant fiber in terms of transmission and also the grating inscription conditions necessary to write radiation tolerant FBGs in such fibers with a femto-second laser. The response of different classes of gratings was also studied under radiation at high doses (>1MGy). The comparison between F- and Ge-doped fibers was highlighted.
White light sources filtered with fiber Bragg gratings for RF-photonics applications
2003
Abstract In this paper we demonstrate that broadband light emitters filtered with fiber Bragg gratings are a suitable light source for RF-photonics applications. A 0.075 nm bandwidth fiber grating illuminated by a light emitter of 40 nm bandwidth has been used as light source to feed a microwave phase shifter based on a chirped fiber Bragg grating. The device operates successfully in the tested frequency range (0.5–6) GHz and has been optically tuned in a range of 4 nm.
Fiber Bragg gratings with various chirp profiles made in etched tapers
1996
We have studied, both theoretically and experimentally, fibre Bragg gratings with a number of different chirp profiles. These chirp profiles can be easily achieved with a recently demonstrated technique involving a taper of desired profile being etched into the cladding of a fibre. Performances of gratings with linear, quadratic, periodically modulated and step chirp profiles are numerically analysed. The versatility of the technique is demonstrated when linearly and quadratically chirped gratings were made as examples of continuous chirp and gratings with step chirps were made as examples of discontinuously chirped structure.
Simple high-resolution wavelength monitor based on a fiber Bragg grating
2004
A compact and low-cost device for monitoring the peak wavelength of single-peak spectral distributions is presented. The system is based on the transmission properties of a fiber Bragg grating when its period is modulated. Different types of optical signal, such as the emission of distributed-feedback lasers and the reflection of a broadband optical source produced by fiber gratings used in sensor systems, can be measured with this device. We demonstrate that a high wavelength resolution of micro 1 pm can be achieved and that our proposal can be used for real-time monitoring.
A dual-wavelength tunable laser with superimposed fiber Bragg gratings
2013
We report a dual-wavelength tunable fiber laser. The cavity is formed by two superimposed fiber Bragg gratings (FBGs) and a temperature tunable high-birefringence fiber optical loop mirror (FOLM). FBGs with wavelengths of 1548.5 and 1538.5 nm were printed in the same section of a fiber using two different masks. The superimposed FBGs were placed on a mechanical mount that allows stretch or compression of the FBGs. As a result of the FBG strain both lines are shifted simultaneously. Dual-wavelength generation requires a fine adjustment of the cavity loss for both wavelengths.
Ultra-flat SPM-broadened spectra in a highly nonlinear fiber using a fiber Bragg grating based parabolic pulse shaper
2006
We demonstrate the generation of ultra-flat broadened spectra by seeding a nonlinear fiber with parabolic pulses shaped using a fiber grating. Applications in pulse compression and spectral slicing are shown.