Search results for "Photonic Crystal"
showing 10 items of 218 documents
Effects of structural irregularities on modulational instability phase matching in photonic crystal fibers
2004
International audience; The effect of structural irregularities in photonic crystal fibers on scalar and vector modulational instability (MI) processes is studied by numerical simulations and experiments. For an anomalous-dispersion regime pump, variations in core ellipticity as small as 0.5% over length scales of the order of several meters are shown to have a negligible effect on scalar MI, yet they completely suppress vector MI. In contrast, for a normal-dispersion regime pump, vector MI is shown to be robust against such fluctuations.
Nodal solitons and the nonlinear breaking of discrete symmetry
2005
We present a new type of soliton solutions in nonlinear photonic systems with discrete point-symmetry. These solitons have their origin in a novel mechanism of breaking of discrete symmetry by the presence of nonlinearities. These so-called nodal solitons are characterized by nodal lines determined by the discrete symmetry of the system. Our physical realization of such a system is a 2D nonlinear photonic crystal fiber owning C6v symmetry.
Spectral analog of the Gouy phase shift
2013
We demonstrate the existence of the spectral phase shift a pulse experiences when it is subjected to spectral focusing. This $\frac{\ensuremath{\pi}}{2}$ phase shift is the spectral analog of the Gouy phase shift a 2D beam experiences when it crosses its focal plane. This spectral Gouy phase shift is measured using spectral interference between a reference pulse and a negatively chirped parabolic pulse experiencing spectral focusing in a nonlinear photonic crystal fiber. To avoid inherent phase instability in the measurement, both reference and parabolic pulses are generated with a $4\mathrm{\text{\ensuremath{-}}}f$ pulse shaper and copropagate in the same fiber. We measure a spectral phase…
Spatial Solitons in Quadratic 2D Nonlinear Photonic Crystals
2007
We report on the first investigations into parametric solitary-wave formation in 2D nonlinear photonic crystals and present experimental results obtained in an hexagonally poled LiNbO3 waveguide designed for twin-beam second harmonic generation at telecom wavelengths.
Gap solitons and modulation instability in a dynamic Bragg grating with nonlinearity management
2008
International audience; We investigate the occurrence of modulation instability in systems in which a dynamic Bragg grating consists of alternating positive and negative Kerr coefficients. The dependence of modulation instability gain spectra over the perturbation wavenumber and system parameters is portrayed near and at the edges of the photonic band gap structure. Further, we demonstrate the generation of traveling gap solitons near the photonic band gap structure through the modulation instability
Inverse photonic-crystal-fiber design through geometrical and material scalings
2020
Geometrical and material - i.e., external and internal - scaling symmetries are exploited to obtain approximated analytical expressions for the mode effective index, group index, and chromatic dispersion of a scaled fiber. Our results include material refractive index scaling that changes the numerical aperture. First, the analytical expressions are successfully tested with a conventional step index fiber in a broadband range of wavelengths, from 1 to 2 mu m. Then, we establish a procedure to adapt the analytical expressions to photonic crystal fibers (PCFs) and illustrate its application in a triangular PCF with circular holes. These adapted analytical expressions show good agreement with …
Tunable defects in colloidal photonic crystals
2006
We present a bottom-up approach for the construction of tunable functional defects in colloidal photonic crystals (CPCs). These structures incorporate polyelectrolyte multilayer (PEM) planar defects embedded in silica CPCs through a combination of evaporation induced self-assembly and microcontact transfer printing. We show how the enormous chemical diversity inherent to PEMs can be harnessed to create chemically active defect structures responsive to solvent vapor pressures, light, temperature as well as redox cycling. A sharp transmission state within the photonic stopband, induced by the PEM defect, can be precisely, reproducibly and in some cases reversibly tuned by these external stimu…
Modelling leaky photonic wires: a mode solver comparison
2006
We present results from a mode solver comparison held within the framework of the European COST P11 project. The structure modelled is a high-index contrast photonic wire in silicon-oninsulator subject to substrate leakage. The methods compared are both in-house developed and commercial, and range from effective index and perturbation methods, over finite-element and finite-difference codes, beam propagation methods, to film mode matching methods and plane wave expansion methods.
Bloch surface waves engineering in one-dimensional photonic crystals with a chiral cap layer
2019
We investigate the localization properties of surface waves created at the interface between a truncated 1D photonic crystal and homogeneous medium in the presence of a chiral cap layer using the transfer matrix method. The numerical results show that the interface can support surface waves with both transverse electric and transverse magnetic polarizations. We demonstrate that the surface waves can be engineered by varying the chirality parameter of the cap layer, which plays an important role in controlling and localization of surface states. It is shown that the effect of a chirality parameter on surface waves with transverse electric polarization is more remarkable compared with surface…
State Preparation and Tomography of a Nanomechanical Resonator with Fast Light Pulses
2018
Pulsed optomechanical measurements enable squeezing, non-classical state creation and backaction-free sensing. We demonstrate pulsed measurement of a cryogenic nanomechanical resonator with record precision close to the quantum regime. We use these to prepare thermally squeezed and purified conditional mechanical states, and to perform full state tomography. These demonstrations exploit large photon-phonon coupling in a nanophotonic cavity to reach a single-pulse imprecision of 9 times the mechanical zero-point amplitude $x_\mathrm{zpf}$. We study the effect of other mechanical modes which limit the conditional state width to 58 $x_\mathrm{zpf}$, and show how decoherence causes the state to…