Search results for "Modula"
showing 10 items of 1481 documents
Optical wave turbulence: Toward a unified nonequilibrium thermodynamic formulation of statistical nonlinear optics
2014
International audience; The nonlinear propagation of coherent optical fields has been extensively explored in the framework of nonlinear optics, while the linear propagation of incoherent fields has been widely studied in the framework of statistical optics. However, these two fundamental fields of optics have been mostly developed independently of each other, so that a satisfactory understanding of statistical nonlinear optics is still lacking. This article is aimed at reviewing a unified theoretical formulation of statistical nonlinear optics on the basis of the wave turbulence theory, which provides a nonequilibrium thermodynamic description of the system of incoherent nonlinear waves. W…
X-Ray Eclipse Time Delays in 4U2129+47
2007
4U 2129+47 was discovered in the early 80's and classified as an accretion disk corona source due to its broad and partial X-ray eclipses. The 5.24 hr binary orbital period was inferred from the X-ray and optical light curve modulation, implying a late K or M spectral type companion star. The source entered a low state in 1983, during which the optical modulation disappeared and an F8 IV star was revealed, suggesting that 4U 2129+47 might be part of a triple system. The nature of 4U 2129+47 has since been investigated, but no definitive conclusion has been reached. Here, we present timing and spectral analyses of two XMM-Newton observations of this source, carried out in May and June, 2005.…
Parabolic pulse evolution in normally dispersive fiber amplifiers preceding the similariton formation regime
2006
We show analytically and numerically that parabolic pulses and similaritons are not always synonyms and that a self-phase modulation amplification regime can precede the self-similar evolution. The properties of the recompressed pulses after SPM amplification are investigated. We also demonstrate that negatively chirped parabolic pulses can exhibit a spectral recompression during amplification leading to high-power chirp-free parabolic pulses at the amplifier output.
Dielectric metalenses with engineered point spread function
2017
High-index silicon nanoblocks support excitation of both electric and magnetic resonance modes at telecommunication wavelengths. At frequencies where both electric and magnetic resonance modes are excited simultaneously, changing the geometrical dimensions of the silicon cubes creates a 2π full span over the phase of the transmitted light in different amplitude ranges. We take advantage of the additional power-flux modulation of the scattered signal to focus the incident light with desired full width at half maximum (FWHM) and side lobe levels (SLLs) in both the lateral and axial directions. By implementing proper amplitude filters within the telecommunication working wavelength (1.55 μm), …
Arbitrary Waveform Generator Based on All-Incoherent Pulse Shaping
2006
An all-incoherent technique for the generation of arbitrary electromagnetic intensity profiles is presented. It is based on spectral filtering of a broadband continuous-wave light source so that the filtered spectral density function (SDF) becomes the user-defined waveform. After large temporal modulation and subsequent distortion in a first-order dispersive medium, the incoherent mapping of the filtered SDF to the time domain occurs. Finally, optical-to-electrical conversion in a fast photodiode allows the optical intensity to be mapped into the electrical domain
Tunable liquid lens equipped virtual reality adapter for scientific, medical, and therapeutic goals
2018
We adapted virtual reality appliances to use them in scientific medical diagnostics and therapeutic aims by incorporated as part of appliance ocular system two electrically tunable Optotune liquid lenses, controllable by computer USB ports within 20D range. In present time we used the appliance to investigate the mono- and/or binocularly illusory perception dominances (Shapiro and al;2008), nonlinearities caused by controversial Gestalt recognition of motion. Back layer of stimuli elements contained internal motion sources - clockwise spinning disk on neutral background. Disk consisted of centrosymmetric radial rays which luminance was sinus mode modulated along the disc circumference. Spin…
Buffering optical topological data using passive Kerr resonators
2018
We experimentally demonstrate the existence of dissipative polarization domain walls, in a normally dispersive Kerr resonator. Through deterministic manipulation of the laser driving the resonator, we achieve systematic excitation and locking of the domain walls.
Laser Pulse Effects in Two-level Systems Driven by Coherent and Fluctuating Radiation Fields
1988
Abstract We reconsider the problem of a two-level system interacting with a radiation field in order to study some new features suggested by the actual experimental conditions. Pulse shape and duration effects are included in the formalism and the counter-rotating terms are retained. The criterion of validity of the rotating wave approximation (RWA) for pulsed fields is investigated; generalizing results well known in RWA, we establish some new formal results, including non-RWA contributions to all orders and for any pulse shape. The analysis is then carried out for fluctuating fields, by developing a method based on the theory of multiplicative stochastic differential equations. For short …
Experimental observation of the generation of cutoff solitons in a discreteLCnonlinear electrical line
2014
We address the problem of supratransmission of waves in a discrete nonlinear system, driven at one end by a periodic excitation at a frequency lying above the phonon band edge. In an experimental electrical transmission line made of 200 inductance-capacitance LC cells, we establish the existence of a voltage threshold for a supratransmission enabling the generation and propagation of cut-off solitons within the line. The decisive role of modulational instability in the onset and development of the process of generation of cut-off solitons is clearly highlighted. The phenomenon of dissipation is identified as being particularly harmful for the soliton generation, but we show that its impact …
Single-step superresolution by interferometric imaging
2009
The use of vertical-cavity surface-emitting laser (VCSEL) arrays for implementation of incoherent source superresolution is presented. The method uses an interferometer setup to obtain superresolution in a single step. The novelty of the method relies on the use of a VCSEL array as the light source, which provides a set of coherent sources which are mutually incoherent. The technique accomplishes the transmission of several spatial frequency bands of the object's spectrum in parallel by use of spatial multiplexing that occurs because of the tilted illumination of the source array. The recording process is done by interference of each frequency band with a complementary set of reference plan…