Exact bidirectional X-wave solutions in fiber Bragg gratings

We find exact solutions describing bidirectional pulses propagating in fiber Bragg gratings. They are derived by solving the coupled-mode theory equations and are expressed in terms of products of modified Bessel functions with algebraic functions. Depending on the values of the two free parameters the general bidirectional X-wave solution can also take the form of a unidirectional pulse. We analyze the symmetries and the asymptotic properties of the solutions and also discuss about additional waveforms that are obtained by interference of more than one solutions. Depending on their parameters such pulses can create a sharp focus with high contrast

Supersymmetric Laser Arrays

The theoretical framework of supersymmetry (SUSY) aims to relate bosons and fermions -- two profoundly different species of particles -- and their interactions. While this space-time symmetry is seen to provide an elegant solution to many unanswered questions in high-energy physics, its experimental verification has so far remained elusive. Here, we demonstrate that, notions from supersymmetry can be strategically utilized in optics in order to address one of the longstanding challenges in laser science. In this regard, a supersymmetric laser array is realized, capable of emitting exclusively in its fundamental transverse mode. Our results not only pave the way towards devising new schemes for scaling up radiance in integrated lasers, but also on a more fundamental level, they could shed light on the intriguing synergy between non-Hermiticity and supersymmetry

The modalities of Iranian soft power: from cultural diplomacy to soft war

Through exploring Iran's public diplomacy at the international level, this article demonstrates how the Islamic Republic's motives should not only be contextualised within the oft-sensationalised, material or ‘hard’ aspects of its foreign policy, but also within the desire to project its cultural reach through ‘softer’ means. Iran's utilisation of culturally defined foreign policy objectives and actions demonstrates its understanding of soft power's potentialities. This article explores the ways in which Iran's public diplomacy is used to promote its soft power and craft its, at times, shifting image on the world stage

Electromagnetic wave scattering by a superconductor

The interaction between radiation and superconductors is explored in this paper. In particular, the calculation of a plane standing wave scattered by an infinite cylindrical superconductor is performed by solving the Helmholtz equation in cylindrical coordinates. Numerical results computed up to $\mathcal{O}(77)$ of Bessel functions are presented for different wavelengths showing the appearance of a diffraction pattern.Comment: 3 pages, 3 figure