Search results for "Shaping"
showing 10 items of 128 documents
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.
Amplifier similariton fiber laser with nonlinear spectral compression
2012
International audience; We propose a new concept of a fiber laser architecture supporting self-similar pulse evolution in the amplifier and nonlinear spectral pulse compression in the passive fiber. The latter process allows for transform-limited picosecond pulse generation, and improves the laser's power efficiency by preventing strong spectral filtering from being highly dissipative. Aside from laser technology, the proposed scheme opens new possibilities for studying nonlinear dynamical processes. As an example, we demonstrate a clear period-doubling route to chaos in such nonlinear laser system.
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.
Effects of fourth-order fiber dispersion on ultrashort parabolic optical pulses in the normal dispersion regime
2011
International audience; We propose a new method for the generation of both triangular-shaped optical pulses and flat-top, coherent supercontinuum spectra using the effect of fourth-order dispersion on parabolic pulses in a passive, normally dispersive highly nonlinear fiber. The pulse re-shaping process is described qualitatively and is compared to numerical simulations.
Ultimate field-free molecular alignment by combined adiabatic-impulsive field design
2008
We show that a laser pulse designed as an adiabatic ramp followed by a kick allows one to reach a perfect postpulse molecular alignment, free of saturation. The mechanism is based on an optimized distribution of the energy between a weakly efficient but non saturating adiabatic ramp and an efficient but saturating impulsive field. Unprecedent degrees of alignment are predicted using state-of-the-art pulse shaping techniques and non-destructive field intensities. The scheme can be extended to reach high degrees of orientation of polar molecules using designed half-cycle pulses.
Human error contribution to accidents in the manufacturing sector: A structured approach to evaluate the interdependence among performance shaping fa…
2023
Since the 1970s, Human Reliability Analysis (HRA) methods have received a great interest for the quantification of the Human Error Probability (HEP) in Nuclear Power Plants (NPPs). To this purpose, the second-generation HRA methods consider contextual and cognitive factors - named Performance Shaping Factors (PSFs) - that may influence the workers’ performance during tasks execution. Despite the recent extension of HRA methods to different fields, only few studies refer to the manufacturing sector. In addition, the majority of contributions assume the independence among PSFs, which may result in an over or under estimation of HEP. Therefore, the present paper focuses on the manufacturing se…
A MCDM-based methodology to evaluate the mutual influence among performance shaping factors
2022
In recent decades, risk analysts have widely focused on Human Reliability Analysis (HRA) methods to assess the contribution of human errors to system failures, also considering contextual and cognitive factors named Performance Shaping Factors (PSFs). Initially implemented in the field of Nuclear Power Plants (NNPs), HRA methods have been extended to different sectors in recent years. Despite that, the majority of contributions in the field assume the independence among PSFs, which may result in an over or under estimation of the Human Error Probability (HEP). Therefore, the present paper proposes a DEMATEL-based approach to evaluate the mutual influence between PSFs proposed by the SPARH m…
Filtering out intersymbol interference in spread-spectrum communication systems
1979
In this letter the transfer characteristic of the optimum filter suitable for eliminating intersymbol interference in pseudo-noise spread-spectrum communication systems is determined. Such a characteristic is independent of the code sequence employed.
Iterative approach to the exponential representation of the time–displacement operator
2005
An iterative method due to Voslamber is reconsidered. It provides successive approximations for the logarithm of the time–displacement operator in quantum mechanics. The procedure may be interpreted, a posteriori, as an infinite re-summation of terms in the so-called Magnus expansion. A recursive generator for higher terms is obtained. From two illustrative examples, a detailed comparative study is carried out between the results of the iterative method and those of the Magnus expansion.
High harmonics generation from structured nanorings
2014
In this work we study the radiation diffused by a fictitious structured nanoring driven by an intense laser field. In our model we consider an electron moving through a cosine-shape potential. The results show that the ring, under particular conditions, emits a wide spectrum of harmonics.