ABSTRACT
Infrared fiber materials such as chalcogenide, tellurite, and heavily germanium-doped silica glasses are attractive materials for many applications based on nonlinear optical effects such as Kerr, Raman, and Brillouin processes. Here, we experimentally demonstrate a close-to-single-frequency Brillouin fiber laser in the 2-µm wavelength region either based on tellurite (TeO2) glass or on heavily germanium-doped silica glass. Our results reveal a strong enhancement of the Brillouin gain efficiency at 2 µm of more than 50 times that of standard silica optical fibers. A lasing threshold and narrow linewidth of 98 mW and 48 kHz, respectively, have been demonstrated in the tellurite fiber-based laser. This simple Brillouin laser source configuration confirms the potential applications of such fibers for the development of nonlinear photonic devices in the important 2-µm spectral range.
ABSTRACT
We report the observation of all-optical polarization pulling of an initially polarization-scrambled signal using parametric amplification in a highly nonlinear optical fiber. Broadband polarization pulling has been achieved both for the signal and idler waves with up to 25 dB gain using the strong polarization sensitivity of parametric amplifiers. We further derive the probability distribution function for the final polarization state, assuming a randomly polarized initial state, and we show that it agrees well with the experiments.
Subject(s)
Amplifiers, Electronic , Computer Simulation , Fiber Optic Technology/instrumentation , Optical Fibers , Computer-Aided Design , Equipment Design , Nonlinear DynamicsABSTRACT
We present experimental and numerical results demonstrating the simultaneous frequency-selective excitation of several guided acoustic Brillouin modes in a photonic crystal fiber with a multi-scale structure design. These guided acoustic modes are identified by using a full vector finite-element model to result from elastic radial vibrations confined by the wavelength-scale air-silica microstructure. We further show the strong impact of structural irregularities of the fiber on the frequency and modal shape of these acoustic resonances.
ABSTRACT
In this paper we investigate the effect of microstructure irregularities and applied strain on backward Brillouin scattering by comparing two photonic crystal fibers drawn with different parameters in order to minimize diameter and microstructure fluctuations. We fully characterize their Brillouin properties including the gain spectrum and the critical power. Using Brillouin echoes distributed sensing with a high spatial resolution of 30 cm we are able to map the Brillouin frequency shift along the fiber and get an accurate estimation of the microstructure longitudinal fluctuations. Our results reveal a clear-cut difference of longitudinal homogeneity between the two fibers.
Subject(s)
Models, Theoretical , Refractometry/instrumentation , Refractometry/methods , Transducers , Computer Simulation , Computer-Aided Design , Crystallization , Equipment Design , Equipment Failure Analysis , Light , Photons , Scattering, RadiationABSTRACT
We provide a complete experimental characterization of stimulated Brillouin scattering in a 160 m long solid-core photonic crystal fiber, including threshold and spectrum measurements as well as position-resolved mapping of the Brillouin frequency shift. In particular, a three-fold increase of the Brillouin threshold power is observed, in excellent agreement with the spectrally-broadened Brillouin gain spectrum. Distributed measurements additionally reveal that the rise of the Brillouin threshold results from the broadband nature of the gain spectrum all along the fiber and is strongly influenced by strain. Our experiments confirm that these unique fibers can be exploited for the passive control or the suppression of Brillouin scattering.
ABSTRACT
Baida and Van Labeke recently proposed a structure that exhibits a supertransmission of light through an array of nanometric coaxial apertures in a metallic film that has been named an annular aperture array (AAA) [Opt. Commun. 209, 17 (2002); Phys. Rev. B 67, 155314 (2003); J. Microsc. 213, 140 (2003)]. We present the first experimental study, to our knowledge, of an AAA structure in the visible region. For technological reasons, the structure under study does not produce a supertransmission of 80% as in Baida and Van Labeke [Opt. Commun. 209, 17 (2002)]. We built the nanostructure and experimentally recorded its far-field spectral response. This transmission shows only one broad band with a maximum around lambda = 700 nm, giving a maximum efficiency around 17%. A finite-difference time-domain simulation reproduces quite well the obtained transmission spectrum.
ABSTRACT
We report the observation of large self-deflection of 2-D bright photorefractive solitons in LiNbO3 crystal under a dc applied field. Beam deflection as large as 300 microm after a 7 mm propagation distance is reported, leading to formation of curved 2-D waveguides. We attribute this large deflection to the low level of impurity acceptors present in the samples, as confirmed by numerical results from a time-dependent photorefractive model.
ABSTRACT
The nonlinear propagation of a partially coherent continuous-wave laser beam in single-mode optical fibers is investigated both theoretically and experimentally, with a special attention to the zero-dispersion wavelength region where modulation instability is expected. Broadband asymmetric spectral broadening is reported experimentally and found in fairly good agreement with a numerical Schrödinger simulation including a phase-diffusion model for the partially coherent beam. This model shows in addition that the underlying spectral broadening mechanism relies not only on modulation instability but also on the generation of high-order soliton-like pulses and dispersive waves. The coherence degradation which results from these ultrafast phenomena is confirmed by autocorrelation measurement.
ABSTRACT
We show experimentally that the two-component multimode spatial optical vector soliton, i.e., a two-hump self-guided laser beam, exhibits in Kerr media a sharp space-inversion symmetry-breaking instability. The experiment is performed in a CS2 planar waveguide using the orthogonal circular polarization states of light as the two components of the vector soliton.
ABSTRACT
Dark photorefractive photovoltaic spatial solitons are demonstrated at 532 nm in nominally undoped and slightly Fe-doped LiNbO(3) planar optical waveguides. The spatial solitons are observed in a transient regime before transverse modulation instability occurs. Their widths are intensity independent as predicted by theory. Meanwhile, excited mode distribution and Fe-doping concentration are shown to influence soliton width. The guiding properties of soliton-induced waveguides are also presented.
ABSTRACT
We demonstrate efficient frequency conversion with large frequency shifts of an anti-Stokes signal into a parametrically seeded Stokes idler, which is generated by a highly mismatched three-wave mixing interaction and subsequent Raman amplification in a normally dispersive single-mode fiber. The use of non-phase-matched waves in Raman-assisted three-wave mixing interactions overcomes the strict spectral limitations imposed by phase-matching conditions in parametric frequency-conversion processes.
ABSTRACT
We propose a picosecond single-beam open Z-scan experiment in which the usual apertured detection scheme is replaced by a two-dimensional single-shot CCD camera. This enables us to extract the two-dimensional transverse modifications of the whole far-f ield pattern that are due to nonlinear refraction as well as to measure the induced nonlinear phase shift with increased sensitivity compared with that of the conventional Z scan.
