In 1998, Bender and Boettcher found that a wide class of Hamiltonians, even though non-Hermitian, can still exhibit entirely real spectra provided they obey parity-time requirements or PT symmetry. Here we demonstrate experimentally passive PT-symmetry breaking within the realm optics. This phase transition leads to loss induced optical transparency in specially designed pseudo-Hermitian guiding potentials.

We report the first observation of Airy optical beams. This intriguing class wave packets, initially predicted by Berry and Balazs in 1979, has been realized both one- two-dimensional configurations. As demonstrated our experiments, these beams can exhibit unusual features such as ability to remain diffraction-free over long distances while they tend freely accelerate during propagation.

We investigate the acceleration dynamics of quasi-diffraction-free Airy beams in both one- and two-dimensional configurations. show that this class finite energy waves can retain their intensity features over several diffraction lengths. The possibility other physical realizations involving spatiotemporal wave packets is also considered.

Parity-time (PT) symmetric periodic structures, near the spontaneous PT-symmetry breaking point, can act as unidirectional invisible media. In this regime, reflection from one end is diminished while it enhanced other. Furthermore, transmission coefficient and phase are indistinguishable those expected in absence of a grating. The phenomenon robust even presence Kerr nonlinearities, also effectively suppress optical bistabilities.

The ability to control the modes oscillating within a laser resonator is of fundamental importance. In general, presence competing can be detrimental beam quality and spectral purity, thus leading spatial as well temporal fluctuations in emitted radiation. We show that by harnessing notions from parity-time (PT) symmetry, stable single–longitudinal mode operation readily achieved system coupled microring lasers. selective breaking PT symmetry used systematically enhance maximum attainable...

We investigate the effect of nonlinearity on beam dynamics in parity-time ($\mathcal{P}\mathcal{T}$) symmetric potentials. show that a novel class one- and two-dimensional nonlinear self-trapped modes can exist optical $\mathcal{P}\mathcal{T}$ synthetic lattices. These solitons are shown to be stable over wide range potential parameters. The transverse power flow within these complex is also examined.

Starting from Lagrangian principles we develop a formalism suitable for describing coupled optical parity-time symmetric systems.

Physical systems exhibiting topological invariants are naturally endowed with robustness against perturbations, as manifested in insulators-materials robust electron transport, immune from scattering by defects and disorder. Recent years have witnessed intense efforts toward exploiting these phenomena photonics. Here we demonstrate a nonmagnetic insulator laser system topologically protected transport the cavity. Its properties give rise to single-mode lasing, defects, considerably higher...

We show that a nonlinear array of coupled waveguides can exhibit discrete self-focusing in the continuum approximation obeys so-called Schrödinger equation. This process has much common with biophysical model Davydov.

We investigate both theoretically and experimentally the self-healing properties of accelerating Airy beams. show that this class waves tends to reform during propagation in spite severity imposed perturbations. In all occasions reconstruction these beams is interpreted through their internal transverse power flow. The robustness optical scattering turbulent environments also studied experimentally. Our observations are excellent agreement with numerical simulations.

We experimentally investigate the evolution of linear and nonlinear waves in a realization Anderson model using disordered one dimensional waveguide lattices. Two types localized eigenmodes, flat-phased staggered, are directly measured. Nonlinear perturbations enhances localization type, induce delocalization other. In complementary approach, we study on short time scales $\delta$-like wavepackets presence disorder. A transition from ballistic wavepacket expansion to exponential (Anderson)...

Plasma channel generation (or filamentation) using ultraintense laser pulses in dielectric media has a wide spectrum of applications, ranging from remote sensing to terahertz lightning control. So far, filamentation been triggered with the use ultrafast axially symmetric spatial beam profiles, thereby generating straight filaments. We report experimental observation curved plasma channels generated air femtosecond Airy beams. In this unusual propagation regime, tightly confined main...

Topological insulators are phases of matter characterized by topological edge states that propagate in a unidirectional manner is robust to imperfections and disorder. These attributes make insulator systems ideal candidates for enabling applications quantum computation spintronics. We propose concept exploits effects unique way: the laser. lasers whose lasing mode exhibits topologically protected transport without magnetic fields. The underlying properties lead highly efficient laser,...

We show that nonlinear optical structures involving a balanced gain-loss profile can act as unidirectional valves. This is made possible by exploiting the interplay between fundamental symmetries of parity ($\mathcal{P}$) and time ($\mathcal{T}$), with effects. dynamics specifically demonstrated for case an integrable $\mathcal{PT}$-symmetric system.

We observe optical trapping and manipulation of dielectric microparticles using autofocusing radially symmetric Airy beams. This is accomplished by exploiting either the inward or outward transverse acceleration associated with their chirped wavefronts. experimentally demonstrate, for first time to our knowledge, that such beams morph into nondiffracting Bessel in far-field. Furthermore, ability guiding transporting along primary rings this class explored.

We demonstrate that optical discrete solitons are possible in appropriately oriented biased photorefractive crystals. This can be accomplished optically induced periodic waveguide lattices created via plane-wave interference. Our method paves the way towards observation of entirely new families solitons. These include, for example, two-dimensional self-focusing and defocusing different group symmetries, incoherently coupled vector solitons, soliton states diatomic chains, as well their...

We introduce a new class of (2+1)D spatial and (3+1)D spatiotemporal waves that tend to autofocus in an abrupt fashion. While the maximum intensity such radial wave remains almost constant during propagation, it suddenly increases by orders magnitude right before its focal point. These can be generated through use radially symmetric Airy or appropriately superimposing packets. Possible applications abruptly focusing beams are also discussed.

We report the first experimental observation of discrete solitons in an array optically induced waveguides. The waveguide lattice is real time by illuminating a photorefractive crystal with pair interfering plane waves. demonstrate two types bright solitons: in-phase self-localized states and staggered (pi out-of-phase) soliton family. This experiment any physical system. Our scheme paves way for reconfigurable focusing defocusing photonic lattices where low-power (mW) can be thoroughly investigated.