Search results for "BAND"
showing 10 items of 2610 documents
Generation of a 160-GHz transform-limited pedestal-free pulse train through multiwave mixing compression of a dual-frequency beat signal.
2002
International audience; We report the experimental generation of a 160-GHz picosecond pulse train at 1550 nm, using multiple four-wave mixing temporal compression of an initial dual-frequency beat signal in the anomalous-dispersion regime of a nonzero dispersion-shifted fiber. Complete intensity and phase characterizations of the pulse train were carried out by means of a frequency-resolved optical gating technique, showing that 1.27-ps transform-limited pedestal-free Gaussian pulses were generated.
Nanobox array for silicon-on-insulator luminescence enhancement at room temperature
2006
We report the light extraction enhancement obtained at room temperature from a square lattice of crystalline silicon nanoboxes etched in a silicon-on-insulator substrate. Luminescence spectra recorded under optical pumping show a 125 times emission enhancement as compared with the reference unpatterned silicon-on-insulator emission. In light of band diagram calculations, it is demonstrated that the emission enhancement partially results from the coupling between electron-hole recombination inside the silicon boxes and low group velocity optical modes of the array. Moreover, it is observed that these modes present different decoupling lengths and that a complete extraction of luminescence ca…
Analysis of the angular acceptance of surface plasmon Bragg mirrors
2007
International audience; We analyze an important aspect of the behavior of surface plasmon polariton (SPP) Bragg mirrors: the dependence of the angular acceptance for reflection on the incidence angle. By means of leakage radiation microscopy, both in direct and Fourier space, we observe that the angular acceptance diminishes for increasing incidence angles. This effect, which can considerably affect the design of devices based on these elements, is shown to be the consequence of the decrease of the bandgap width with increasing incidence angle. (c) 2007 Optical Society of America.
Bloch mode coupling investigation in silicon-on-insulator W1 photonic crystal waveguide
2004
We report in this paper the study of a W1 photonic crystal waveguide which supports two Bloch modes having 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, evidence the even mode propagation along the defect line and experimental spectrum is discussed in light of band diagram and FDTD calculations. 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 wav…
Generation of aperiodic picosecond pulses sequences from incoherent optical waves
2007
We present an original method to generate optical pulses trains with random time-interval values from incoherent broadband sources. Our technique relies on the remarkable properties of a line made of cascaded SPM-based optical regenerators.
Gain sideband splitting in dispersion oscillating fibers
2014
International audience; We analyze the modulation instability spectrum in a varying dispersion optical fiber as a function of the dispersion oscillation amplitude, and predict a novel sideband splitting into different sub-sidebands for relatively large dispersion oscillations
On the possibility of observing bound soliton pairs in a "wave-breaking-free" mode-locked fiber laser
2007
To generate ultrashort pulses with higher energy in passively mode-locked fiber lasers, several groups have recently focused on the development of laser cavities operating in normal path-averaged dispersion, with a view to achieve wave-breaking-free operation. The mode-locking mechanism in fiber laser play a key role in providing scalability limitation: for instance, nonlinear polarization evolution can be overdriven. Furthermore, the differential gain of the doped fiber decreases along with the traveled distance. From all of these limitations, it follows that power scalability is always bounded for virtually any mode-locked laser cavity design. In general, the consequence is the emergence …
Experimental and theoretical study of line mixing in methane spectra. III. The Q branch of the Raman nu(1) band
2000
International audience; The shape of the nu(1) Raman Q branch of CH4 perturbed by Ar and He at room temperature has been studied. Stimulated Raman spectroscopy (SRS) experiments have been made in the 2915-2918 cm(-1) spectral region for total pressures from 0.4 to 70 atm and mixtures of approximate to 5% CH4 with He and Ar. Analysis of the spectra demonstrates that the shape of the Q branch is significantly influenced by line mixing and much narrower than what is predicted by the addition of individual line profiles. For the first time, a model is proposed for the calculation and analysis of the effects of collisions on the considered spectra. In this approach, the rotational part of the re…
All-fibered high-quality 28-GHz to 112 GHz pulse sources based on nonlinear compression of optical temporal besselons
2021
The generation of high quality pulse trains at repetition rates of several tens of GHz remains a crucial step for optical telecommunications, optical sampling or component testing applications. Unfortunately, the current bandwidth limitations of optoelectronic devices do not allow the direct generation of well-defined optical pulse trains with low duty cycles. An attractive solution is based on a direct temporal phase modulation that is then converted into an intensity modulation thanks to a dispersive element that imprints a spectral quadratic phase. Picosecond pulses at repetition rates of several tens of GHz have been successfully demonstrated [1] . However, this approach suffers from a …
Stabilisation of modelocking in fibre ring laser through pulse bunching
2001
Bunching of equally spaced pulses is reported to be the most stable mode of operation in a passively modelocked fibre ring laser. The ring includes dispersion management, which results in the absence of strict pulse energy quantisation, giving pulse bunching a better immunity to environmental perturbation.