We experimentally demonstrate PT-symmetric optical lattices with periodical gain and loss profiles in a coherently prepared four-level N-type atomic system. By appropriately tuning the pertinent parameters, onset of PT-symmetry breaking is observed through measuring an abrupt phase-shift jump between adjacent waveguides. The experimental realization such readily reconfigurable effectively controllable waveguide array structure sets new stage for further exploiting better understanding...

The unique combination of lightweight, strength, corrosion resistance, high-temperature and biocompatibility make Ti6Al4V alloy an important material in metal contact solar cells, selective laser melting (SLM) enables the production parts complex geometries that would be difficult or impossible to produce using traditional manufacturing methods. build orientation SLM process presents essential effect on quality produced parts, thus, this study it investigates impact multi-build (0°, 30°,...

Edge states emerge in diverse areas of science, offering new opportunities for the development novel electronic or optoelectronic devices, sound and light propagation controls acoustics photonics. Previous experiments on edge exploration topological phases photonics were carried out mostly linear regimes, but current belief is that nonlinearity introduces striking features into physics states, lead-ing to formation solitons, optical isolation, lasing, name a few. Here we experimentally...

Beams of ``squeezed'' light have important applications in quantum metrology and gravitational-wave detection. The authors generate twin beams correlated photons using parametrically amplified four- six-wave mixing a nonlinear optical crystal. This medium offers several advantages, such as better on-chip integration than atomic vapors, plus longer coherence time traditional materials. These achievements can also find potential application all-optical communication storage photonic circuits.

Topological defects, such as quantum vortices, determine the properties of fluids. Their study has been at center activity in solid state and BEC communities. In parallel, nontrivial behavior linear wave packets with complex phase patterns was investigated by singular optics. Here, we formation, evolution, interaction optical vortices Dirac point photonic graphene. We show that while their exact goes beyond equation requires a full account lattice properties, it can be still approximately...

Spin–orbit coupling of electromagnetic waves is one the most important effects in topological photonics, but so far it has not been studied photonic graphene implementations based on paraxial configuration, particular, atomic vapor cells. We generate experimentally a honeycomb refractive index pattern such cell using electromagnetically induced transparency. demonstrate that an effective spin–orbit appears as correction to beam equations because strong spatial gradients permittivity. It...

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We establish a link between the fractional Schr\"odinger equation (FSE) and light propagation in honeycomb lattice (HCL) - Dirac-Weyl (DWE). The Laplacian FSE causes modulation of dispersion relation system, which limiting case becomes linear. In HCL, is already linear around Dirac point, suggesting possible connection with FSE. Here, we demonstrate this by describing both using DWE. Thus, propagate Gaussian beams according to FSE, HCL DWE, discover very similar behavior conical diffraction....

Narrow-band intensity-difference squeezing (IDS) beams have important applications in quantum metrology and gravitational wave detection. The best way to generate narrow-band IDS is employ a parametrically amplified (PA) four-wave mixing (FWM) process high-gain atomic media. Such can be further enhanced by cascading multiple PA FWM processes separate complicated experimental setup, added losses, mechanical stability limit the wide use of such scheme practical applications. Here we show that...

Atomic media are important in optics research since they can be conveniently manipulated and controlled due to easy selection of atomic levels, laser fields, the active adjustment many system parameters. In this paper, we investigate optical Bloch oscillation, Zener tunneling, Bloch–Zener oscillation both theoretically numerically. We use two coupling fields prepare dynamical lattice through interference. To induce a transverse force, make frequency difference between increase linearly along...

The Klein paradox consists in the perfect tunneling of relativistic particles through high potential barriers. As a curious feature particle physics, it is responsible for exceptional conductive properties graphene. It was recently studied context atomic condensates and topological photonics phononics. While theory holds only normal incidence, so far angular dependence its strong variation with barrier height were not measured experimentally. In this work, we capitalize on versatility vapor...

We experimentally demonstrate the Talbot effect resulting from repeated self-reconstruction of a spatially intensity-modulated probe field under Fresnel near-field regime. By launching beam into an optically induced atomic lattice (established by interfering two coupling fields) inside rubidium vapor cell, we can obtain diffracted pattern formed electromagnetically grating (EIG) in three-level $\Lambda$-type Doppler-free configuration with assistance transparency (EIT). The EIG-based...

We investigate controllable spatial modulation of circular autofocusing Airy beams, under action different dynamic linear potentials, both theoretically and numerically.We introduce a novel treatment method in which the beam is represented as superposition narrow azimuthally-modulated one-dimensional beams that can be analytically treated.The potentials are appropriately designed, so effect either weakened or even eliminated when potential exerts "pulling" on beam, if "pushing" effect,...

A wide class of non-Hermitian Hamiltonians can possess entirely real eigenvalues when they have parity-time (PT) symmetric potentials. Recently, this family systems has attracted considerable attention in diverse areas physics due to their extraordinary properties, especially optical based on solid-state materials, such as coupled gain–loss waveguides and microcavities. Considering the desired refractive index be effectively manipulated through atomic coherence, it is important realize...

We experimentally generate a vortex beam through four-wave mixing (FWM) process after satisfying the phase-matching condition in rubidium atomic vapor cell with photonic band gap (PBG) structure. The observed FWM can also be viewed as reflected part of launched probe from PBG. Further, we investigate propagation behaviors, including spatial shift and splitting vortices medium enhanced Kerr nonlinearity induced by electromagnetically transparency. This Letter useful for better understanding...

For the first time, we study parametric amplification process of multi-wave mixing (PA-MWM) signal and cascaded-nonlinearity (CNP) in sodium vapors both theoretically experimentally, based on a conventional phase-conjugate MWM self-diffraction four-wave (SD-FWM) processes, which are pumped by laser or amplified spontaneous emission (ASE), respectively. pumping case, SD-FWM serves as quantum linear amplifier (a CNP) out (inside) resonant absorption region. While for ASE only CNP occurs output...