We demonstrate the presence of parity-time (PT) symmetry for non-Hermitian two-state Hamiltonian a dissipative microwave billiard in vicinity an exceptional point (EP). The shape depends on two parameters. is determined from measured resonance spectrum fine grid parameter plane. After applying purely imaginary diagonal shift to Hamiltonian, its eigenvalues are either real or complex conjugate curve, which passes through EP. An appropriate basis choice reveals PT symmetry. Spontaneous...

Taming laser instabilities Broad-area and high-power lasers often suffer from owing to the chaotic interference of multiple modes within cavity. Such can ultimately limit operation or damage The usual approach minimizing such is number in Bittner et al. designed a cavity that disrupts formation self-organized structures lead (see Perspective by Yang). This fighting chaos with using boundary condition shape may provide robust route stabilizing at high operating powers. Science , this issue p....

Random numbers are widely used for information security, cryptography, stochastic modeling, and quantum simulations. Key technical challenges physical random number generation speed scalability. We demonstrate a method ultrafast of hundreds bit streams in parallel with single laser diode. Spatio-temporal interference many lasing modes specially designed cavity is introduced as scheme greatly accelerated generation. Spontaneous emission, caused by fluctuations, produces noise that makes the...

We present measurements of transmission and reflection spectra a microwave photonic crystal composed 874 metallic cylinders arranged in triangular lattice. The show clear evidence Dirac point, characteristic spectrum relativistic massless fermions. In fact, points are peculiar property the electronic band structure graphene, whose properties consequently can be described by equation. vicinity measured resemble those obtained conductance scanning tunneling microscopy graphene flakes.

This paper presents experimental results on properties of waves propagating in an unbounded and a bounded photonic crystal consisting metallic cylinders that are arranged triangular lattice. First, we present transmission measurements plane traversing crystal. The experiments performed the vicinity Dirac point, i.e., isolated conical singularity band structure. There, shows pseudodiffusive $1/L$ dependence, with $L$ being thickness crystal, phenomenon also observed graphene. Second,...

Nonlinear disordered systems are not only a model system for fundamental studies but also in high demand practical applications. However, optical nonlinearity based on intrinsic material response is weak random scattering systems. Here, we propose and experimentally realize highly nonlinear mapping between the potential emerging light of reconfigurable multiple-scattering cavity. A quantitative analysis degree reveals its dependence number events. The effective order can be tuned over wide...

The optical memory effect has emerged as a powerful tool for imaging through multiple-scattering media; however, the finite angular range of limits field view. Here, we demonstrate experimentally that selective coupling incident light into high-transmission channel increases memory-effect range. This enhancement is attributed to robustness channels against perturbations such sample tilt or wave front tilt. Our work shows provide an enhanced view memory-effect-based diffusive media.

The ray dynamics of optical cavities exhibits bifurcation points: special geometries at which trajectories switch abruptly between stable and unstable. A prominent example is the Fabry-Perot cavity with two planar mirrors, widely employed for broad-area semiconductor lasers. Such support lasing in a relatively small number transverse modes, laser highly susceptible to filamentation irregular pulsations. Here we demonstrate experimentally that slight deviation from this point (planar cavity)...

We report on experiments with deformed polymer microlasers that have a low refractive index and exhibit unidirectional light emission. demonstrate the highly directional emission is due to transport of rays along unstable manifold chaotic saddle in phase space. Experiments, ray-tracing simulations, mode calculations show very good agreement.

Scattering experiments with microwave cavities were performed and the effects of broken time-reversal invariance (TRI), induced by means a magnetized ferrite placed inside cavity, on an isolated doublet nearly degenerate resonances investigated. All elements effective Hamiltonian this two-level system extracted. As function two experimental parameters, associated eigenvectors could be tuned to coalesce at so-called exceptional point (EP). The behavior eigenvalues when encircling EP in...

We experimentally study the synchronization of chaos generated by semiconductor lasers in a cascade injection configuration, i.e., tunable master laser is used to generate optical transmitter that injects light into receiver laser. Chaos between and achieved with correlation coefficient 90 % for measurement bandwidth up 35 GHz. Two parameter regions good are found, corresponding alignment oscillation frequencies either or

Quantum wires and electromagnetic waveguides possess common features since their physics is described by the same wave equation. We exploit this analogy to investigate experimentally with microwave theoretically help of an effective potential approach occurrence bound states in sharply bent quantum wires. In particular, we compute states, study transition from a unbound state caused variation bending angle, determine critical angles at which such takes place. The predictions are confirmed...

Cuboid-shaped organic microcavities containing a pyrromethene laser dye and supported upon photonic crystal have been investigated as an approach to reducing the lasing threshold of cavities. Multiphoton lithography facilitated fabrication cuboid cavities directly on substrate or decoupling structure, while similar structures were fabricated by UV for comparison. Significant reduction factor ~30 has observed relative those substrate. The mode spectra microresonators provide strong evidence...

Open dielectric resonators of different shapes are widely used for the manufacture microlasers. A precise determination their resonance frequencies and widths is crucial design. Most microlasers have a flat cylindrical geometry, two-dimensional approximation, so-called method effective index refraction, commonly employed numerical calculations. Our aim has been an experimental test precision applicability model based on this approximation. We performed very thorough accurate measurements two...

The length spectra of flat three-dimensional dielectric resonators circular shape were determined from a microwave experiment. They compared to semiclassical trace formula obtained within two-dimensional model based on the effective index refraction approximation and good agreement was found. It necessary take into account dispersion for approximation. Furthermore, small deviations between experimental spectrum prediction attributed systematic error In summary, methods developed in this...

We investigated experimentally the ray-wave correspondence in organic microlasers of various triangular shapes. Triangular billiards are interest since they simplest cases polygonal and existence properties periodic orbits triangles not yet fully understood. The with symmetric shapes that were exhibited states localized on simple orbits, their lasing characteristics like spectra far-field distributions could be well explained by orbits. Furthermore, asymmetric do feature studied. Their found...

We investigate experimentally and theoretically the lasing behavior of dielectric microcavity lasers with chaotic ray dynamics. Experiments show multimode for both D-shaped stadium-shaped wave-chaotic cavities. Theoretical calculations also find different shapes, sizes refractive indices. While there are quantitative differences between theoretical spectra stadium D-cavity, due to presence scarred modes anomalously high quality factors, these decrease as system size increases, substantially...

The emission from open cavities with non-integrable features remains a challenging problem of practical as well fundamental relevance. Square-shaped dielectric microcavities provide favorable case study generic implications for other polygonal resonators. We report on joint experimental and theoretical square-shaped organic microlasers exhibiting far-field that is strongly concentrated in the directions parallel to side walls cavity. A semiclassical model distributions developed agreement...

Resonance spectra of two-dimensional dielectric microwave resonators circular and square shapes have been measured. The deduced length periodic orbits were analyzed a trace formula for recently proposed by Bogomolny et al. [Phys. Rev. E 78, 056202 (2008)] was tested. observed deviations between the experimental predictions are attributed to large number missing resonances in measured spectra. We show that taking into account systematics fully understood. In particular, connection most...

We investigated the frequency spectra and field distributions of a dielectric square resonator in microwave experiment. Since such systems cannot be treated analytically, experimental studies their properties are indispensable. The momentum representation measured shows that all resonant modes localized on specific classical tori billiard. Based these observations semiclassical model was developed. It excellent agreement with but single class will separately.

We experimentally investigate spatiotemporal lasing dynamics in semiconductor microcavities with various geometries, featuring integrable or chaotic ray dynamics. The classical directly impacts the dynamics, which is primarily determined by local directionality of long-lived trajectories. optical propagation dictates characteristic length scales intensity variations, play a pivotal role nonlinear light-matter interactions. While wavelength-scale variations tend to stabilize modulation on...

We design and fabricate an on-chip laser source that produces a directional beam with low spatial coherence. The lasing modes are based on the axial orbit in stable cavity have good directionality. To reduce coherence of emission, number transverse is maximized by fine-tuning geometry. In size hundreds micrometers, 1000 lase simultaneously independently, reducing speckle contrast to 0.03. Decoherence reached few nanoseconds as result frequency detuning modes. Such rapid decoherence will...