Pawel S. Jung

• PhD
• Warsaw University of Technology

Topological quantum photonics explores the interaction of the topology of the dispersion relation of photonic materials with the quantum properties of light. The main focus of this field is to create robust photonic quantum information systems by leveraging topological protection to produce and manipulate quantum states of light that are resilient...

By utilizing the theoretical tools of optical thermodynamics, we investigate thermalization in nonlinear disordered lattices beyond the diffusion regime. Even under extreme levels of disorder, we analytically predict the expected thermal value of entropy and the associated Rayleigh-Jeans distribution, once thermalization ensues. In this context, we...

We establish a thermodynamic framework for an all-optical Joule-Thomson expansion process in multimoded nonlinear systems. We experimentally demonstrate that power from single-site inputs can universally condense into the fundamental mode of a waveguide lattice.

We discover and discuss the giant oscillations of stable soliton-molecules as induced by the violation of the action-reaction principle in optical systems ruled by competing nonlinear nonlocal interactions.

We report the first experimental observation of a novel fundamental soliton class, termed Tower and Volcano solitons, in soft-matter systems characterized by nonlinear responses driven by competing nonlocal interactions.

The theory of optical thermodynamics provides a comprehensive framework that enables a self-consistent description of the intricate dynamics of nonlinear multimoded photonic systems. This theory, among others, predicts a pressurelike intensive quantity (p^) that is conjugate to the system’s total number of modes (M)—its corresponding extensive vari...

Statistical mechanics demands that the temperature of a system is positive provided that its internal energy has no upper bound. Yet if this condition is not met, it is possible to attain negative temperatures for which higher-order energy states are thermodynamically favored. Although negative temperatures have been reported in spin and Bose-Hubba...

We show that, in the presence of radially symmetric random perturbations, the orbital angular momenta of a multimode nonlinear fiber will relax into a Rayleigh-Jeans distribution characterized by a well-defined optical temperature and chemical potential.

From biological ecosystems to spin glasses, connectivity plays a crucial role in determining the function, dynamics, and resiliency of a network. In the realm of non-Hermitian physics, the possibility of complex and asymmetric exchange interactions (|kappa_ij| not equal to |kappa_ji|) between a network of oscillators has been theoretically shown to...

From biological ecosystems to spin glasses, connectivity plays a crucial role in determining the function, dynamics, and resiliency of a network. In the realm of non-Hermitian physics, the possibility of complex and asymmetric exchange interactions ( $$\left| {\kappa _{ij}} \right| \ne \left| {\kappa _{ji}} \right|$$ κ i j ≠ κ j i ) between a netwo...

The chaotic evolution resulting from the interplay between topology and nonlinearity in photonic systems generally forbids the sustainability of optical currents. Here, we systematically explore the nonlinear evolution dynamics in topological photonic lattices within the framework of optical thermodynamics. By considering an archetypical two-dimens...

We develop a rigorous theoretical framework based on principles from statistical mechanics that allows one to predict the equilibrium response of classical non-Hermitian arrangements in the weakly nonlinear regime. In this respect, we demonstrate that a pseudo-Hermitian configuration can always be driven into thermal equilibrium when a proper nonli...

We show that the orbital angular momentum (OAM) of a light field can be thermalized in a nonlinear cylindrical multimode optical waveguide. We find that upon thermal equilibrium, the maximization of the optical entropy leads to a generalized Rayleigh-Jeans distribution that governs the power modal occupancies with respect to the discrete OAM charge...

The ability to tailor the hopping interactions between the constituent elements of a physical system could enable the observation of unusual phenomena that are otherwise inaccessible in standard settings. In this regard, a number of recent theoretical studies have indicated that an asymmetry in either the short- or long-range complex exchange const...

We study the propagation dynamics of bright optical vortex solitons in nematic liquid crystals with a nonlocal reorientational nonlinear response. We investigate the role of optical birefringence on the stability of these solitons. In agreement with recent experimental observations, we show that birefringence-induced astigmatism can eventually dest...

We theoretically investigate a Thouless pumping scheme in the one-dimensional topological Su-Schrieffer-Heeger (SSH) model for single and multiple band-gap systems when implemented in a discrete nematic liquid crystal arrangement. For an electrically controlled SSH waveguide array, we numerically demonstrate edge-to-edge light transport at low powe...

We theoretically investigate a Thouless pumping scheme in the 1D topological Su-Schrieffer-Heeger (SSH) model for single and multiple band-gaps systems when implemented in a discrete nematic liquid crystal arrangement. For an electrically controlled SSH waveguide array, we numerically demonstrate edge-to-edge light transport at low power levels. On...

Most acousto-optic lenses produce energy dissipating annular fringes. Here, we report a 3D dynamic focusing with fully-localized focus and 477-fold beam confinement with an extended depth of field (DoF) of more than 28 cm.

We show that the orbital angular momentum (OAM) of a light field can be thermalized in a nonlinear cylindrical multimode optical waveguide. We find, that upon thermal equilibrium, the maximization of the optical entropy leads to a generalized Rayleigh-Jeans distribution that governs the power modal occupancies with respect to the discrete OAM charg...

Light-sheet fluorescence microscopy has greatly improved the speed and overall photostability of optically sectioning cellular and multi-cellular specimens. Similar gains have also been conferred by light-sheet Raman imaging; these schemes, however, rely on diffraction limited Gaussian beams that hinder the uniformity and size of the imaging field-...

The ability to tailor the hopping interactions between the constituent elements of a physical system could enable the observation of unusual phenomena that are otherwise inaccessible in standard settings1,2. In this regard, a number of recent theoretical studies have indicated that an asymmetry in either the short- or long-range complex exchange co...

The collective response of a system is profoundly shaped by the interaction dynamics between its constituent elements. In physics, tailoring these interactions can enable the observation of unusual phenomena that are otherwise inaccessible in standard settings, ranging from the possibility of a Kramer’s degeneracy even in the absence of spin to the...

We investigate scalar and vector multi-hump spatial solitons resulting from competing Kerr-like nonlinear responses excited in a nonlocal medium by either one or two (mutually incoherent) light beams. Two-color vector supermode solitons are more amenable to control but exhibit an intriguing form of spontaneous symmetry breaking in propagation.

The collective response of a system is profoundly shaped by the interaction dynamics between its constituent elements. In physics, tailoring these interactions can enable the observation of unusual phenomena that are otherwise inaccessible in standard settings, ranging from the possibility of a Kramer's degeneracy even in the absence of spin to the...

We present a new scaling law that relates the thermodynamic pressure with the electrodynamic forces in multimode nonlinear dielectric waveguides. Our results are in exact agreement with those obtained using the Maxwell stress tensor formalism.

We study optical thermalization dynamics in integrated photonic coupled-cavity arrangements on a Si3N4 platform. We show that isolated photonic bandgap modes can reach positive or negative temperatures that can be predicted effortlessly using optical thermodynamics.

We demonstrate that, due to nonlinear interactions, the orbital angular momentum in a multimode optical fiber can reach a thermal equilibrium state that is characterized by a temperature and a generalized Rayleigh-Jeans distribution.

We report on the first observation of a gain-induced topological response in a photonic lattice exhibiting asymmetric long-range interactions enabled by unidirectional microrings under pumping. This new platform is used to implement the Haldane lattice.

The complex nonlinear behaviors of heavily multimode lightwave structures have been recently the focus of considerable attention. Here we develop an optical thermodynamic approach capable of describing the thermalization dynamics in large scale nonlinear photonic chain networks - a problem that has remained unresolved so far. A Sackur-Tetrode equat...

We study the propagation dynamics of bright optical vortex solitons in nematic liquid crystals with a nonlocal reorientational nonlinear response. We investigate the role of optical birefringence on the stability of these solitons. In agreement with recent experimental observations, we show that the birefringence-induced astigmatism can eventually...

The convoluted nonlinear behaviors of heavily multimode photonic structures have been recently the focus of considerable attention. The sheer complexity associated with such multimode systems, allows them to display a host of phenomena that are otherwise impossible in few-mode settings. At the same time, however, it introduces a set of fundamental...

Light-sheet microscopy enables considerable speed and phototoxicity gains, while quantitative-phase imaging confers label-free recognition of cells and organelles, and quantifies their number-density that, thermodynamically, is more representative of metabolism than size. Here, we report the fusion of these two imaging modalities onto a standard in...

By utilizing notions from statistical mechanics, we develop a general and self-consistent theoretical framework capable of describing any weakly nonlinear optical multimode system involving conserved quantities. We derive the fundamental relations that govern the grand canonical ensemble through maximization of the Gibbs entropy at equilibrium. In...

We show that the optical brightness of a high-intensity multimode beam can be substantially enhanced using thermodynamic optical cooling schemes enabled by nonlinear interactions. This can be achieved without violating the second law of thermodynamics.

We show that a nonlinear topological Haldane lattice can exhibit a number of intriguing thermodynamic properties such as a metastable response leading to different temperatures in two bands or thermal equilibrium at different chemical potentials.

We demonstrate that in nonlinear waveguide arrangements, the optical thermodynamic pressure results from the electrodynamic force exerted on the guiding interface and from an entropy growth term associated with an irreversible expansion.

We report the first experimental observation of optical thermodynamic processes in nonlinear mesh photonic lattices. These include Rayleigh-Jeans distributions with either positive or negative temperatures, isentropic expansions and compressions, as well as Joule photon gas expansions.

We report on the first demonstration of a topological Haldane lattice in a photonic setting using active microring structures.

Over the last few years, parity-time (PT) symmetry has been the focus of considerable attention. Ever since, pseudo-Hermitian notions have permeated a number of fields ranging from optics to atomic and topological physics, as well as optomechanics, to mention a few. Unlike their Hermitian counterparts, nonconservative systems do not exhibit a prior...

We show that, in general, any complex weakly nonlinear highly multimode system can reach thermodynamic equilibrium, characterized by a unique temperature and chemical potential. The conditions leading to either positive or negative temperatures are explicitly obtained in terms of the linear spectrum of the system, the input power, and the correspon...

We show that, in general, any complex weakly nonlinear highly multimode system can reach thermodynamic equilibrium that is characterized by a unique temperature and chemical potential. The conditions leading to either positive or negative temperatures are explicitly obtained in terms of the linear spectrum of the system, the input power, and the co...

We theoretically investigate the effect of linear absorption on the stability of nonlinear vortex beams in dye-doped nematic liquid crystals. We show that the combined effects of intensity attenuation and thermal defocusing provide a stabilization mechanism which significantly extends the stable propagation distance of the vortex beam for first- an...

Parity-time (PT) symmetry has attracted a lot of attention since the concept of pseudo-Hermitian dynamics of open quantum systems was first demonstrated two decades ago. Contrary to their Hermitian counterparts, non-conservative environments a priori do not show real energy eigenvalues and unitary evolution. However, if PT-symmetry requirements are...

We study experimentally the interaction of mutually incoherent bright spatial solitons in dye-doped nematic liquid crystals (LCs). The dye-induced light absorption results in a complex nonlinear optical response of the LC having spatially nonlocal focusing and defocusing contributions. The competition between both nonlinearities leads to the separa...

Under thermal equilibrium conditions, we show that the zeroth law of thermodynamics can be used to measure a soliton’s optical temperature in a nonlinear multimode system. Here, the modal gas plays the role of an optical thermometer.

We introduce a new design for implementing the topological Haldane laser on a nonmagnetic platform. Unit cells are provided for detuned nearest neighbor coupling and imaginary next-nearest neighbor coupling based on microring laser networks.

We show that the zeroth law of thermodynamics can be used to measure a soliton’s optical temperature in a nonlinear multimode system. Here, the modal gas plays the role of an optical thermometer.

In this work, we introduce a straightforward and original approach for evanescent field boundary conditions (EBCs), which can be, in principle, applied in both Beam Propagation Method (BPM) and Finite Difference Time Domain Method (FDTD) numerical simulations. Importantly, suggested method may serve as an efficient alternative to typically applied...

We report on the first experimental observation of stable vortex solitons in nematic liquid crystals with nonlocal nonlinear reorientational response. We show how these nonlinear vortex beams can be formed and confined in extraordinary optical waves by employing the cell with no lateral boundary conditions and the application of an external magneti...

In this work, we investigate a thin-film polarizer for a high intensity electromagnetic (EM) beam based on Cr nano wire arrays. Commonly used thin-film polarizing components are very sensitive for high power of EM waves and can be easily damaged by focused beams. The solution to this problem could be a thin-film polarizer based on metallic subwavel...

We study light propagation in nematic liquid crystals in the context of spatial optical solitons formation. We propose a simple analytical model with multiplicative nonlinearity, which represents (qualitatively) the liquid crystal response by comprising the competition between focusing (reorientational) and defocusing (thermal) nonlocal nonlinearit...

We study numerically formation of spatial optical solitons in nematic liquid crystals with competing nonlocal nonlinearities. We demonstrate that at the sufficiently high input power the interplay between focusing and thermally induced defocusing may lead to the formation of two-peak fundamental spatial solitons. These solitons have constant spatia...

We study numerically formation of spatial optical solitons in nematic liquid crystals with competing nonlocal nonlinearities. We demonstrate that at the sufficiently high input power the interplay between focusing and thermally induced defocusing may lead to the formation of two-peak fundamental spatial solitons. These solitons have constant spatia...

In this paper we have investigated the alignment of nematic liquid crystal (NLC) molecules in homogenously oriented liquid crystal cells used for nematicons generation. We propose three different methods based on contrast evaluation, linear diffraction and nematicons generation. We showed that LC cell contrast evaluation is not enough from the pers...

We employ a thick layer of chiral nematic liquid crystals to demonstrate the evolution of a one-dimensional (1D) higher-order guided mode into a beam self-confined in both transverse dimensions at various wavelengths. We also report the experimental observation of higher-order modes guided by soliton-induced waveguides in chiral nematic liquid crys...

We investigate a non-homogeneous layered structure encompassing dual spatial dispersion: continuous diffraction in one transverse dimension and discrete diffraction in the orthogonal one. Such dual diffraction can be balanced out by one and the same nonlinear response, giving rise to light self-confinement into astigmatic spatial solitons: self-foc...

We demonstrate the evolution of higher order one-dimensional guided modes into two-dimensional solitary waves in a reorientational medium. The observations, carried out at two different wavelengths in chiral nematic liquid crystals, are in good agreement with a simple nonlocal nonlinear model.

In this paper theoretical and experimental results regarding discrete light propagation in photonic liquid crystal fibres (PLCFs) are presented. Particular interest is focused on tunability of the beam guidance obtained due to the variation in either external temperature or optical power (with assumption of thermal nonlinearity taking place in liqu...

In this paper, the results of theoretical analyses and experimental tests related to the light propagation in the photonic crystal fiber (PCF) infiltrated with liquid crystal (LC) are presented. While refractive index of the inclusion is higher than that of silica glass, analyzed photonic structure can be considered as a matrix of mutually parallel...

Simulation of light beam propagation in optical fiber with a high step index requires the use of complicated methods. One of the simplest and accurate method is presented in this paper. The possibility of use of beam propagation method with exact boundary conditions in light beam propagation in optical fibers is shown in this work. The comparison o...

In this paper a simple and effective method to analyze rectangular media with a high step of the refractive index is shown. Comparison of the method with a classical Beam Propagation Method and with analytical solutions for the planar waveguides in the (1+1)dimensional case are presented. There is also shown an influence of a high step of refractiv...

The influence of smoke on THz imaging was examined. We tested experimentally a passive THz camera - TS4 from ThruVision Systems Ltd. The camera detects natural human radiation at a frequency of 0.25THz. The distance camera-target could be 3-15 meters. Moreover, Time Domain Spectroscopy was used to investigate the influence of the amount of smoke on...