Search results for "Physics::Optics"
showing 10 items of 1958 documents
Optical gratings induced by field-free alignment of molecules
2006
We analyze the alignment of molecules generated by a pair of crossed ultra-short pump pulses of different polarizations by a technique based on the induced time-dependent gratings. Parallel polarizations yield an intensity grating, while perpendicular polarizations induce a polarization grating. We show that both configurations can be interpreted at moderate intensity as an alignment induced by a single polarized pump pulse. The advantage of the perpendicular polarizations is to give a signal of alignment that is free from the plasma contribution. Experiments on femtosecond transient gratings with aligned molecules were performed in CO2 at room temperature in a static cell and at 30 K in a …
Extreme statistics in Raman fiber amplifiers : from experiments to analytical description
2010
International audience; We describe the concept of an all-fibered device that enables the optical magnification of the amplitude jitter of low-fluctuation pulse trains, facilitating the measurement of the statistical properties by usual photodiodes and electronic equipments. Taking advantage of a highly nonlinear fiber with anomalous dispersion followed by central optical bandpass filtering, we experimentally demonstrate an amplification of small-scale fluctuations by a factor 10.
Nonlinear dynamics of temporal optical soliton molecules in lasers
2007
Recent experiments demonstrate that fiber laser cavities are able to support various multisoliton complexes, analogous to soliton molecules. These advances, which could have impact on optical information transmission or storage, are guided by the concept of dissipative soliton and supported by numerical simulations. DOI: 10.2529/PIERS060828120520 As passively mode-locked lasers rely strongly on nonlinear dissipation, there is a growing interest in understanding various pulse dynamics in terms of the dynamics of dissipative solitons [1]. In particular, the interaction between dissipative temporal solitons can lead to the formation of stable multi-soliton complexes. The stability of multi-sol…
Tailored soliton statistics in supercontinuum generation
2009
Supercontinuum (SC) generation in highly nonlinear photonic crystal fibers (PCF) has stimulated tremendous interest in recent years [1]. Particular results that have received recent widespread attention concern the observation of “optical rogue waves,” statistically rare extreme red-shifted Raman solitons appearing on the long wavelength edge of the SC spectrum [2]. Further numerical analysis of these fluctuations have showed explicitly that the rogue soliton statistics exhibit strongly non-Gaussian extreme-value characteristics [3]. The previous studies of optical rogue wave statistics in SC generation have been carried out considering PCF with only one zero dispersion wavelength (ZDW). It…
Modal attraction on low order modes by Kerr effect in a graded refractive index multimode fiber
2018
Modal attraction towards low order modes in a GRIN multimode fiber was experimentally observed at high power and characterized, thus enriching the dynamics of the Kerr self-cleaning effect leading to quasi fundamental mode generation.
Optical flip-flop memory and data packet switching operation based on polarization bistability in a telecommunication optical fiber
2013
We report the experimental observation of bistability and hysteresis phenomena of the polarization signal in a telecommunication optical fiber. This process occurs in a counterpropagating configuration in which the optical beam nonlinearly interacts with its own Bragg-reflected replica at the fiber output. The proof of principle of optical flip–flop memory and 10 Gbit/s routing operation is also reported based on this polarization bistability. Finally, we also provide a general physical understanding of this behavior on the basis of a geometrical analysis of an effective model of the dynamics. Good quantitative agreement between theory and experiment is obtained.
Experimental demonstration of Bloch mode parity change in photonic crystal waveguide
2004
We experimentally show coupling between two photonic crystal waveguide Bloch modes having a different parity. A monomode ridge waveguide etched in a silicon-on-insulator substrate and connecting to the photonic crystal waveguide allows us to excite the even Bloch mode. Transmission measurements, performed on a broad spectral range, show the even mode propagation along the defect line. Then, spectrally resolved near-field patterns obtained by using a scanning near-field optical microscope in collection mode for wavelengths, inside and outside the multimode region of the photonic crystal waveguide, clearly demonstrate coupling phenomenon between even and odd modes.
Spatiotemporal light-beam compression from nonlinear mode coupling
2017
We experimentally demonstrate simultaneous spatial and temporal compression in the propagation of light pulses in multimode nonlinear optical fibers. We reveal that the spatial beam self-cleaning recently discovered in graded-index multimode fibers is accompanied by significant temporal reshaping and up to four-fold shortening of the injected sub-nanosecond laser pulses. Since the nonlinear coupling among the modes strongly depends on the instantaneous power, we explore the entire range of the nonlinear dynamics with a single optical pulse, where the optical power is continuously varied across the pulse profile.
Nonlinear Multimode Fiber Optics
2018
We overview recent advances in the nonlinear optics of multimode optical fibers, including ultrabroadband sideband and supercontinuum generation, Kerr and Raman beam cleanup, modal modulation instabilities, four wave mixing, and second harmonic beam cleaning.
Two-stage linear-nonlinear shaping of an optical frequency comb as rogue nonlinear-Schrödinger-equation-solution generator
2014
International audience; We report a wave generator of complex solutions of the nonlinear Schrödinger equation (NLSE) combining both intensity and phase spectral shaping of an initial optical frequency comb with subsequent nonlinear propagation in an optical fiber. We apply the explicit analytical form of the two-breather solutions of the NLSE as a linear spectral filter to shape ideal modulation of a continuous wave. The additional nonlinear propagation of the tailored wave provides experimental evidence of both the growth and decay of the fundamental second-order periodic breather solution. The temporal and spectral profiles of the higher-order breather are in excellent agreement with the …