Incorporating many-body effects into modeling of semiconductor lasers and amplifiers

Major many-body effects that are important for semiconductor laser modeling are summarized. The authors adopt a bottom-up approach to incorporate these many-body effects into a model for semiconductor lasers and amplifiers. The optical susceptibility function ({Chi}) computed from the semiconductor Bloch equations (SBEs) is approximated by a single Lorentzian, or a superposition of a few Lorentzians in the frequency domain. Their approach leads to a set of effective Bloch equations (EBEs). The authors compare this approach with the full microscopic SBEs for the case of pulse propagation. Good agreement between the two is obtained for pulse widths longer than tens of picoseconds

Generation and control of extreme-blue shifted continuum peaks in optical Kerr media

We demonstrate tunable, extremely blueshifted continuum in \u3bb=1.055 \u3bcm ultrashort laser pulse filamentation in silica. Close to threshold, the continuum appears as a single, isolated blue peak. The spectral position of the two supercontinuum components can be tuned and a regime with encompassing fundamental and second harmonic is possible to achieve. At higher energies, the continuum expands in bandwidth starting from the blue peak. The spectral dynamics and tunability are explained in terms of X-wave generation and intrafilament pulse splitting which may be controlled by modifying the input pulse focusing conditions

Clamping of the Linewidth Enhancement Factor in Narrow Quantum-Well GRINSCH Semiconductor Lasers

The linewidth enhancement factor in single quantum-well GRINSCH semiconductor lasers is investigated theoretically and experimentally. For thin wells a small linewidth enhancement factor is obtained which clamps with increasing carrier density, in contrast to the monotonous increase observed for thicker wells. Microscopic many-body calculations reproduce the experimental observations attributing the clamping to a subtle interplay between excitation dependent gain shifts and carrier population distributions

A model for interacting instabilities and texture dynamics of patterns

A simple model to study interacting instabilities and textures of resulting patterns for thermal convection is presented. The model consisting of twelve-mode dynamical system derived for periodic square lattice describes convective patterns in the form of stripes and patchwork quilt. The interaction between stationary zig-zag stripes and standing patchwork quilt pattern leads to spatiotemporal patterns of twisted patchwork quilt. Textures of these patterns, which depend strongly on Prandtl number, are investigated numerically using the model. The model also shows an interesting possibility of a multicritical point, where stability boundaries of four different structures meet.Comment: 4 pages including 4 figures, page width revise

Interaction of two modulational instabilities in a semiconductor resonator

The interaction of two neighboring modulational instabilities in a coherently driven semiconductor cavity is investigated. First, an asymptotic reduction of the general equations is performed in the limit of a nearly vertical input-output characteristic. Next, a normal form is derived in the limit where the two instabilities are close to one other. An infinity of branches of periodic solutions are found to emerge from the unstable portion of the homogeneous branch. These branches have a nontrivial envelope in the bifurcation diagram that can either smoothly join the two instability points or form an isolated branch of solutions

High-harmonic generation from a subwavelength dielectric resonator

Published 26 April 2023Higher-order optical harmonics entered the realm of nanostructured solids being observed recently in optical gratings and metasurfaces with a subwavelength thickness. Structuring materials at the subwavelength scale allows us toresonantly enhance the efficiency of nonlinear processes and reduce the size of high-harmonic sources. We report the observation of up to a seventh harmonic generated from a single subwavelength resonator made of AlGaAs material. This process is enabled by careful engineering of the resonator geometry for supporting an optical mode associated with a quasi-bound state in the continuum in the mid-infrared spectral range at around λ = 3.7 μm pump wavelength. The resonator volume measures ~0.1 λ3. The resonant modes are excited with an azimuthally polarized tightly focused beam. We evaluate the contributions of perturbative and nonperturbative nonlinearities to the harmonic generation process. Our work proves the possibility to miniaturize solid-state sources of high harmonics to the subwavelength volumes.Anastasiia Zalogina, Luca Carletti, Anton Rudenko, Jerome V. Moloney, Aditya Tripathi, Hoo-Cheol Lee, Ilya Shadrivov, Hong-Gyu Park, Yuri Kivshar, Sergey S. Kru

Temporal fluctuations of waves in weakly nonlinear disordered media

We consider the multiple scattering of a scalar wave in a disordered medium with a weak nonlinearity of Kerr type. The perturbation theory, developed to calculate the temporal autocorrelation function of scattered wave, fails at short correlation times. A self-consistent calculation shows that for nonlinearities exceeding a certain threshold value, the multiple-scattering speckle pattern becomes unstable and exhibits spontaneous fluctuations even in the absence of scatterer motion. The instability is due to a distributed feedback in the system "coherent wave + nonlinear disordered medium". The feedback is provided by the multiple scattering. The development of instability is independent of the sign of nonlinearity.Comment: RevTeX, 15 pages (including 5 figures), accepted for publication in Phys. Rev.

THEORY OF NONLINEAR WAVEGUIDES : STATIONARY AND PROPAGATING WAVES

On donne un aperçu sur les techniques d'obtention des solutions d'ondes guidée non linéaires et stationnaires, et d'ondes de surface dans les ondes guidées diélectriques, ainsi que détermination de leurs propriétés d'instabilité et l'étude des caractéristiques de propagation.Techniques for obtaining stationary nonlinear guided and surface wave solutions in dielectric waveguides, determining their stability properties and investigating global propagation characteristics will be overviewed

Coupled kinetic Boltzmann electromagnetic approach for intense ultrashort laser excitation of plasmonic nanostructures

We propose a multiphysical computational approach that allows for efficient coupling of full-vector Maxwell-based propagation codes with kinetic Boltzmann equations to investigate the spatial dynamics of non-equilibrium processes in plasmonic nanostructures upon intense laser excitation. Accessing the energy-resolved electron distribution provides a direct path towards multidimensional modeling of transient optical, electron emission, and electron transport processes. Simulations are performed for a gold nanoparticle upon infrared ultrashort-pulse excitation close to the melting threshold, evidencing the interplay between strong intrinsic and (non)thermal nonlinearities and accessing simultaneously the non-equilibrium thermal and propagation dynamics. While delivering the results within a reasonable simulation time and while being open to further extensions, the proposed approach can serve as a reliable compromise between point quantum and space-dimensional classical models. © 2021 American Physical Society.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]