Search results for "Grating"

Study of the angular acceptance of surface plasmon Bragg mirrors

2007

Surface plasmon based photonic devices are promising candidates for highly integrated optics. A surface plasmon (SP) is basically an electromagnetic wave confined in the interface between a metal and a dielectric, and is due to the interaction of the electromagnetic field with the surface bounded electron charges in the metal. A SP can propagate along the interface where it is confined (the propagation length being tens of micrometers in the visible range), but its associated electromagnetic field decreases exponentially in the perpendicular direction, in such a way that this vertical confinement makes SP very attractive for the design of optical devices in coplanar geometry. An important e…

The temporal analogue of diffractive couplers

2020

International audience; Based on the space-time duality of light, we numerically demonstrate that temporal dispersion grating couplers can generate from a single pulse an array of replicas of equal amplitude. The phase-only profile of the temporal grating is optimized by a genetic algorithm that takes into account the optoelectronic bandwidth limitations of the setup.

High spatiotemporal resolution in multifocal processing with femtosecond laser pulses.

2006

We report spatial and temporal dispersion compensation for fan-out of femtosecond pulses with a low-frequency diffraction grating by means of a hybrid diffractive-refractive lens triplet. In this way, we achieve a multifocal light structure with nearly diffraction-limited light spots even for 20 fs pulse duration. The spatial chromatic compensation, which drastically reduces the lateral walk-off of the various spectral components, also allows us to improve the available bandwidth at the dispersion-compensated diffraction orders. In fact, the temporal width of the output pulse is essentially limited by the group-delay dispersion term, which is shown to be small. The high spatiotemporal resol…

All-fibered high-quality low duty-cycle 20-GHz and 40-GHz picosecond pulse sources

2007

International audience; In this work, we demonstrate all-fibered 20-GHz and 40-GHz picosecond pulse sources with duty cycles as low as 1/14. The pulse train is achieved via the high-quality compression of an initial sinusoidal beating through four segments of optical fibers. General design rules are proposed and experimental results are in agreement with numerical predictions.

Ultra-flat SPM-broadened spectra in a highly nonlinear fiber using parabolic pulses formed in a fiber Bragg grating

2006

International audience; We propose a new method for generating flat self-phase modulation (SPM)-broadened spectra based on seeding a highly nonlinear fiber (HNLF) with chirp-free parabolic pulses generated using linear pulse shaping in a superstructured fiber Bragg grating (SSFBG). We show that the use of grating reshaped parabolic pulses allows substantially better performance in terms of the extent of SPM-based spectral broadening and flatness relative to conventional hyperbolic secant (sech) pulses. We demonstrate both numerically and experimentally the generation of SPMbroadened pulses centred at 1542nm with 92% of the pulse energy remaining within the 29nm 3dB spectral bandwidth. Appli…

Tailored waveform generation in mode-locked fiber lasers by in-cavity pulse shaper

2014

International audience; We numerically show the possibility of pulse shaping in a mode-locked fiber laser by inclusion of an amplitude-phase spectral filter into the laser cavity. Various advanced temporal waveforms are generated, including parabolic, flat-top and triangular pulses.

Pulse shaping in mode-locked fiber lasers by in-cavity spectral filter

2014

International audience; We numerically show the possibility of pulse shaping in a passively mode-locked fiber laser by inclusion of a spectral filter into the laser cavity. Depending on the amplitude transfer function of the filter, we are able to achieve various regimes of advanced temporal waveform generation, including ones featuring bright and dark parabolic-, flat-top-, triangular- and saw-tooth-profiled pulses. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for controlling the dynamics of mode-locked fiber lasers.

Effectiveness of nonlinear optical loop mirrors in chirped fiber gratings compensated dispersion-managed transmission systems

2005

International audience; We show that nonlinear optical loop mirrors can dramatically suppress the side peaks induced by the group delay ripples in chirped fiber gratings compensated dispersion-managed systems and significantly improve the system performance.

Tuning And Chirping Fiber Bragg Gratings By A Magnetic Field

2005

A topology for multiple generation system with doubly fed induction machines and indirect matrix converter.

2008

In this paper, a new topology for a grid connected generation system based on two double fed induction generators is presented The scheme uses an indirect matrix converter consisting on an input rectifier, a three-to-two matrix converter which provides a DC voltage, and two voltage fed output converters. The input converter is connected to the grid and each of the output converters is connected to the rotor of the corresponding machine. The rotor currents of each generator are vector controlled and unity power factor operation at the indirect matrix converter input is considered. The duty cycles for the input converter are chosen in order to obtain maximum DC link voltage. The duty cycles f…