Amine Ben Salem

Bio: Amine Ben Salem is an academic researcher from Carthage University. The author has contributed to research in topics: Supercontinuum & Photonic-crystal fiber. The author has an hindex of 11, co-authored 42 publications receiving 523 citations.

Optical communication beyond orbital angular momentum

Abstract: Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks.

Super-flat coherent supercontinuum source in As 38.8 Se 61.2 chalcogenide photonic crystal fiber with all-normal dispersion engineering at a very low input energy.

Abstract: We numerically report super-flat coherent mid-infrared supercontinuum (MIR-SC) generation in a chalcogenide As38.8Se61.2 photonic crystal fiber (PCF). The dispersion and nonlinear parameters of As38.8Se61.2 chalcogenide PCFs by varying the diameter of the air holes are engineered to obtain all-normal dispersion (ANDi) with high nonlinearities. We show that launching low-energy 50 fs optical pulses with 0.88 kW peak power (corresponding to pulse energy of 0.05 nJ) at a central wavelength of 3.7 μm into a 5 cm long ANDi-PCF generates a flat-top coherent MIR-SC spanning from 2900 to 4575 nm with a high spectral flatness of 3 dB. This ultra-wide and flattened spectrum has excellent stability and coherence properties that can be used for MIR applications such as medical diagnosis of diseases, atmospheric pollution monitoring, and drug detection.

Encoding information using Laguerre Gaussian modes over free space turbulence media.

Abstract: We experimentally demonstrate an efficient information transmission technique using Laguerre Gaussian (LG) modes. This technique is based on multiplexing and demultiplexing multiple LG modes with different azimuthal and radial components. At the reception, the initially sent modes encoding the information are extracted with high fidelity using a complete decomposition allowing to identify a particular mode from a set of modes within a unique iteration. Importantly, we investigate the effects of the atmospheric turbulence on the proposed communication system. We believe that the proposed technique is promising for high-bit-rate spatial division multiplexing in optical fiber and free space communication systems.

Highly nonlinear As2Se3-based chalcogenide photonic crystal fiber for midinfrared supercontinuum generation

Abstract: We propose a real, highly nonlinear, As2Se3-based chalcogenide photonic crystal fiber in which a supercontinuum (SC) spanning more than 2 octaves is generated at =2.8 µm in the femtosecond regime. The designed PCF is characterized for ultrabroadband mid-infrared SC generation in only few millimetres of fiber length. A full modal analysis of the optical properties of the fiber is presented in terms of the effective area, the nonlinearity coefficient, and the chromatic dispersion. A second-order Sellmeier approximation is proposed to estimate the variation of the refractive index of the As2Se3 material as a function of wavelength. The numerical study shows that a SC spanning from 1.9 to 4 µm can be generated in the chalcogenide PCF with an air-hole diameter of 1.26 µm and a pitch of 1.77 µm. We examine the interplay of the nonlinear effects that lead to the construction of the SC as a function of the input power and the fiber length. We find that the dynamics behind the SC generation is mainly ruled by the effects of self phase modulation and stimulated Raman scattering. The intrinsic properties of the chalcogenide glasses and the microstructure provide enhanced optical properties and offer numerous applications in the infrared field.

Ultraflat-top midinfrared coherent broadband supercontinuum using all normal As2S5-borosilicate hybrid photonic crystal fiber

Abstract: We report more than two octave spanning mid-IR flat-top supercontinuum (SC) generation using all normal As2S5-borosilicate hybrid photonic crystal fiber Our design is based on a chalcogenide As2S5 photonic crystal fiber (PCF), where the first ring composed of six air holes is made by borosilicate glass By injecting 50-fs pulses with 16 nJ energy at 25 μm in the all normal dispersion (ANDi) regime, a flat-top broadband SC extending from 1 to 5 μm with high-spectral flatness of 8 dB is obtained in only 4-mm fiber length To the best of our knowledge, we present the broadest flat mid-IR spectrum generated in the ANDi regime of an optical fiber The self-phase modulation and the optical wave breaking are identified as the main broadening mechanisms The obtained broadband light source can be potentially used in the field of spectroscopy and in high-resolution optical coherent tomography owing to the high-spectral SC flatness generated by our designed fiber

Principles Of Optics Electromagnetic Theory Of Propagation Interference And Diffraction Of Light

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Orbital angular momentum 25 years on [Invited]

Abstract: Twenty-five years ago Allen, Beijersbergen, Spreeuw, and Woerdman published their seminal paper establishing that light beams with helical phase-fronts carried an orbital angular momentum. Previously orbital angular momentum had been associated only with high-order atomic/molecular transitions and hence considered to be a rare occurrence. The realization that every photon in a laser beam could carry an orbital angular momentum that was in excess of the angular momentum associated with photon spin has led both to new understandings of optical effects and various applications. These applications range from optical manipulation, imaging and quantum optics, to optical communications. This brief review will examine some of the research in the field to date and consider what future directions might hold.

Supercontinuum generation, photonic crystal fiber

Abstract: A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

A review of complex vector light fields and their applications

Abstract: Vector beams, and in particular vector vortex beams, have found many applications in recent times, both as classical fields and as quantum states. While much attention has focused on the creation and detection of scalar optical fields, it is only recently that vector beams have found their place in the modern laboratory. In this review, we outline the fundamental concepts of vector beams, summarise the various approaches to control them in the laboratory, and give a concise overview of the many applications they have spurned.

Underwater Optical Wireless Communications, Networking, and Localization: A Survey

Abstract: Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, the severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: (1) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques (2) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; (3) Network layer topics containing relaying techniques and potential routing algorithms; (4) Transport layer subjects such as connectivity, reliability, flow and congestion control; (5) Application layer goals, and (6) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the prospective directions for underwater optical wireless communications, networking, and localization studies.