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In order to obtain analytical gain expression in Brillouin optical Fiber Amplifiers (BFAs), coupled intensity equations describing the interaction of pump and stokes waves must be solved simultaneously. For long optical fibers, although fiber loss is responsible for the pump depletion and nonnegligible effect, for short optical fibers less than 2 km, its effect can be discarded. In this paper, we provide an accurate analytic expression for the BFA gain for fiber lengths less than 2 km by discarding the optical fiber loss and show results of experimental validation.

A simple approach is proposed for determining peak frequencies, stress heights, stress lengths, full-width at half-maximum (FWHM), broadening and symmetry properties, of a composite Brillouin Gain Spectrum (BGS) which is obtained for the pulse lengths longer than the embedded stress lengths. The composite BGS is thus reconstructed in terms of extracted components. It is validated that the method is successful in determining every level of stress peaks and heights embedded in composite BGS.

An efficient silicon-based light source presents an unreached goal in the field of photonics, due to Silicon’s indirect electronic band structure preventing direct carrier recombination and subsequent photon emission. Here we utilize inelastically tunneling electrons to demonstrate an electrically-driven light emitting silicon-based tunnel junction operating at room temperature. We show that such a junction is a source for plasmons driven by the electrical tunnel current. We find that the emission spectrum is not given by the quantum condition where the emission frequency would be proportional to the applied voltage, but the spectrum is determined by the spectral overlap between the energy-dependent tunnel current and the modal dispersion of the plasmon. Experimentally we find the highest light outcoupling efficiency corresponding to the skin-depth of the metallic contact of this metal-insulator-semiconductor junction. Distinct from LEDs, the temporal response of this tunnel source is not governed by nanosecond carrier lifetimes known to semiconductors, but rather by the tunnel event itself and Heisenberg’s uncertainty principle. Finally We discuss a path for single photon emission via the Coulomb blockade effect leading to single electron tunneling.

We show that inelastically-scattering tunnel electrons are a source for electric plasmon generation. We experimentally demonstrate such electrically-driven light-emitting tunnel junction by forward biasing a Fermi sea against a doped semiconductor across a nanometer-thin tunnel gap. Light emission at room temperature is found in the visible frequency range corresponding to a spectral power dependency of the tunnel current and the plasmonic mode. The response time (speed) of such a tunnel junction scales inverse exponentially with the tunnel gap thickness approaching Tpbs for

Goktas, Hasan/0000-0002-2195-9531 WOS: 000424678900006 PubMed: 29400726 We report on an accurate closed-form analytical model for the gain of a Brillouin fiber amplifier that accounts for material loss in the depleted pump regime. We determined the operational model limits with respect to its relevant parameters and pump regimes through both numerical and experimental validation. As such, our results enable accurate performance prediction of Brillouin fiber amplifiers operating in the weak-pump, high-gain, and saturation regimes alike. (C) 2018 Optical Society of America

We present a comprehensive analysis of the technique of Longitudinal-Mode-Filling (LMF) to reduce Stimulated Brillouin Scattering (SBS) limitations in Ytterbium Doped Fibre Amplifiers (YDFA), for the generation of nanosecond, temporally shaped pulses. A basic Master-Oscillator-Power-Amplifier (MOPA) system, comprising an output YDFA with 10 mu m-core active fibre, is experienced for benchmarking purposes. Input pulse-shaping is operated thanks to direct current modulation in highly multimode laser-diode seeds, either based on the use of Distributed Feed-Back (DFB) or of a Fibre Bragg Grating (FBG). These seeds enable wavelength control. We verify the effectiveness of the combination of LMF, with appropriate mode spacing, in combination with natural chirp effects from the seed to control the SBS threshold in a broad range of output energies, from a few to some tens of mu J. These variations are discussed versus all the parameters of the laser system. In accordance with the proposal of a couple of basic principles and with the addition of gain saturation effects along the active fibre, we develop a full-vectorial numerical model. Fine fits between experimental results and theoretical expectations are demonstrated. The only limitation of the technique arises from broadband beating noise, which is analysed thanks to a simplified, but fully representative description to discuss the signal-to-noise ratio of the amplified pulses. This provides efficient tools for application to the design of robust and cost-effective MOPAs, aiming to the generation of finely shaped and energetic nanosecond pulses without the need for any additional electro-optics. (C) 2014 Optical Society of America

Brussels Photonics Team (B-PHOT);Brussels-Capital Region;Fonds Wetenschappelijk Onderzoek (FWO);The Society of Photo-Optical Instrumentation Engineers (SPIE);Ville de Bruxelles Nonlinear Optics and Its Applications VIII; and Quantum Optics III -- 14 April 2014 through 16 April 2014 -- -- 110770 We present a comprehensive experimental study of the technique of Longitudinal Mode Filling (LMF) applied to the reduction of Stimulated Brillouin Scattering (SBS), in Ytterbium Doped Fibre Amplifiers (YDFA) at the wavelength of 1064 nm. Pulse durations and Mode Field Diameters (MFD) lie in the ranges of 10 - 100 ns and 10 - 35 ?m, respectively. Input pulse-shaping is implemented by means of direct current modulation in multimode Laser-Diode seeds. This evidences a number of interests in the development of robust and low cost Master Oscillator Power Amplifiers (MOPA). Highly energetic, but properly shaped, nanosecond pulses may be produced this way without any need of additional electro-optical means for in-line phase and amplitude modulation. Seeds consist of Distributed Feed- Back (DFB) and Fibre Bragg Gratings (FBG) with different fibre lengths. We demonstrate the benefit of LMF with properly controlled mode spacing, in combination with chirp effects due to fast current transients in the semiconductors, in order to deal with SBS thresholds in the range of a few to some hundred ?J. The variations of the SBS threshold are discussed versus the number of longitudinal modes, the operating conditions of the selected seed and pulse-shaping conditions. © 2015 SPIE.

Purpose – The purpose of this paper is to present the method of lines (MOL) solution of the stimulated Brillouin scattering (SBS) equations (a system of three first-order hyperbolic partial differential equations (PDEs)), describing the three-wave interaction resulting from a coupling between light and acoustic waves. The system has complex numbers and boundary values. Design/methodology/approach – System of three first-order hyperbolic PDEs are first transformed and then spatially discretized. Superbee flux limiter is proposed to offset numerical damping and dispersion, brought on by the low order approximation of spatial derivatives in the PDEs. In order to increase computational efficiency, the structured structure of the PDE Jacobian matrix is identified and a sparse integration algorithm option of the ordinary differential equation (ODE) solvers is used. The flux limiter based on higher order approximations eliminates numerical oscillation. Examples are presented, and the performance of the Matlab ODE solvers is evaluated by comparison. Findings – This type of solution provides a rapid means of investigating SBS as a tool in fiber optic sensing. Originality/value – To the best of the authors' knowledge, MOL solution is proposed for the first time for the modeling of three-wave interaction in a SBS-based fiber optic sensor.

The MATLAB computing environment is a package used extensively throughout industry, research and education by users of a complete range in proficiency. MATLAB provides then an ideal platform to introduce such an item of Boundary Value Problem (BVP) software and indeed, Kierzenka and Shampine (Kierzenka & Shampine, 2001) developed the core BVP Ordinary Differential Equation (ODE) software bvp4c to solve a large class of two-point boundary value problems of the form