09:00  09:30

Marco Ornigotti
(Universität Rostock)
Quantum X Waves with Orbital Angular Momentum in Nonlinear Dispersive media
X waves are solutions of Maxwell's equations, which exhibit neither diffraction nor dispersion during propagation. Traditionally, X waves are understood as superpositions of zeroth order Bessel beams, therefore carrying no orbital angular momentum (OAM). A generalisation to the case of OAMcarrying X waves, however, has been proposed recently, highlighting new features and possibilities, especially in freespace classical and quantum communications [1]. For the latter case, in particular, a careful analysis of he quantum properties of X waves with OAM is needed.
In this work, we present a complete and consistent quantum theory of generalised X waves carrying orbital angular momentum, propagating in nonlinear dispersive media. Our quantisation scheme is based on canonical quantisation in terms of collections of harmonic oscillators solidal with the X wave itself.
Within this framework, we show that the resulting quantised pulses are resilient against external perturbation, due to their intrinsic nondiffracting and nondispersive nature. Moreover, as an example of application of our formalism, we consider explicitly the case of squeezing in $\chi^2$media. Our findings reveal that the OAM carried by the X wave regulates which quadrature of the field is squeezed, while the X wave velocity (namely, its Bessel cone angle) regulates the amount of squeezing. in particular, we show that there exist an optimal Bessel cone angle, for which the squeezing is maximum.
References:
[1] M. Ornigotti, C. Conti and A. Szameit, Phys. Rev. Lett. 115, 100401 (2015).

09:30  09:45

Fabio Revuelta
(Universidad Politecnica de Madrid and ICMAT)
Dynamical localization in nonideal kicked rotators
A new theoretical framework is developed to study dynamical localization (quantum suppression of classical diffusion) in the context of ultracold atoms in periodically shaken optical lattices. Our method is capable to account for finitetime modulations with different shapes, thus going beyond the paradigmatic kicked rotator.

09:45  10:15

Sergej Flach
(nstitute for Basic Science)
Designing and perturbing flatband networks

10:15  10:45

Andrea Fratalocchi
(KAUST University)
Complex epsilonnearzero biomimetic metasurfaces for structural colors, photovoltaics and photocatalysis applications

10:45  11:15

Coffee break

11:15  11:45

Yaroslav Kartashov
(ICFOInstitut de Ciencies Fotoniques)
Edge states and quasisolitons in polariton topological insulators

11:45  12:15

Robert Thomson
(Heriot Watt University)
Photonic lanterns and their applications
I will present some of the work we have conducted in the area of discrete optical analogues using ultrafast laser inscribed waveguide systems. Specifically, I will discuss how we have used this technology to realize flatband and topological systems, and how we are developing new characterization methodologies to extend the capabilities of this powerful platform.

12:15  12:30

Ragnar Fleischmann
(Max Planck Institute for Dynamics and SelfOrganization)
Channeling of branched flow in weakly scattering anisotropic media
When waves propagate through weakly scattering but correlated, disordered environments they are randomly focussed into pronounced branchlike structures, a phenomenon referred to as \emph{branched flow} which has been studied in a wide range of isotropic random media. In many natural environments, however, the fluctuations of the random medium typically show pronounced anisotropies. We study the influence of anisotropy on such natural focusing events and find a strong and nonintuitive dependence on the propagation angle which we explain by stochastic ray theory.

12:30  14:15

Lunch and discussions

14:15  14:45

Kestutis Staliunas
(Universitat Politecnica de Catalunya)
Photonic crystal microchip laser

14:45  15:15

Andrey Sukhorukov
(Australian National University)
Simulation of multidimensional and topological effects in planar waveguide arrays
Optical photonic lattices attract strong interest as a flexible experimental platform with applications ranging from beam shaping and switching to quantum photonics. Importantly, various array designs were suggested by mapping quantum Hamiltonian dynamics to the optical beam evolution.
We suggest a novel concept and formulate a general mathematical procedure to exactly map the system dynamics from arbitrary multidimensional lattices to light propagation in a onedimensional optical waveguide array. We realize this approach experimentally in a fs laser written waveguide lattice, and demonstrate the equivalent mapping of a 2D square lattice to a planar array. We anticipate that our results can open new possibilities for implementation of multidimensional effects, including topological phenomena, in various planar integrated platforms including Si photonic chips.

15:15  15:45

Coffee break

15:45  16:15

Peter Schmelcher
(Universität Hamburg)
Local symmetries as a systematic pathway to the breaking of discrete symmetries in wave propagation

16:15  16:30

Morteza Kamalian Kopae
(Aston University)
Periodic nonlinear Fourier transform in fibreoptic communication
Recent demonstrations of the nonlinear Fourier transform (NFT) based fibreoptic communication systems has shown its potential to overcome some fibre impairments. These systems usually consider the signal to vanish as time tends to infinity. However, working with the periodic signals brings about some benefits which are of avail especially regarding the communication application requirements. To name a few; periodic NFT (PNFT) makes it possible to control the time duration of the signal which makes the encoding procedure of the transmitter more straightforward in comparing with its vanishing signal counterpart. Supporting the idea of inserting cyclic extension to avoid intersymbol interference, the processing window of the PNFT system can be considerably smaller especially in high rate transmissions. On top of that, one can avoid the sudden drop in the signal power ensued from the necessary condition of the conventional NFT to maintain the vanishing boundaries. In this work we simulate and evaluate the performance of a communication system based on PNFT.

16:30  16:45

Sebabrata Mukherjee
Experimental observation of anomalous topological edge modes in a slowlydriven photonic lattice
Topologically protected quantum effects can be observed in a periodically driven system where the Hamiltonian is timeperiodic. In the limit of low frequency driving (driving frequency ~ hopping amplitude), the standard topological invariants, such as Chern numbers, may not be sufficient to describe the topology of the system. In this situation, chiral edge modes can exist even if the Chern numbers of all the bulk bands are zero. We demonstrate the experimental observation of such "anomalous" topological edge modes in a twodimensional photonic lattice, where these propagating edge states are shown to coexist with a quasilocalized bulk.
Ref. Nat. Commun, 8, 13918 (2017).

16:45  17:15

Frank Wise
(Cornell University)
Selforganized instability in multimode optical fiber with disorder

17:15  17:30

Sebastian Schönhuber
(Technische Universität Wien)
Random lasers for broadband directional emission
Broadband coherent light sources are becoming increasingly important for sensing and spectroscopic applications, especially in the midinfrared and terahertz (THz) spectral regions, where the unique absorption characteristics of a whole host of molecules are located. The desire to miniaturize such light emitters has recently led to spectacular advances, with compact onchip lasers that cover both of these spectral regions. The long wavelength and small size of the sources result, however, in a strongly diverging laser beam that is difficult to focus on the target that one aims to perform spectroscopy with. In my presentation I will introduce an unconventional solution to this vexing problem, relying on a random laser to produce coherent broadband THz radiation as well as an almost diffractionlimited farfield emission profile [1]. Our quantum cascade random lasers do not require any finetuning and thus constitute a promising example of practical device applications for random lasing (see a recent discussion of our work in [2]).
References
[1] S. Schönhuber, M. Brandstetter, T. Hisch, C. Deutsch, M. Krall, H. Detz, G. Strasser, S. Rotter, and K. Unterrainer "Random lasers for broadband directional emission," Optica 3, 1035 (2016).
[2] D. S. Wiersma "Optical physics: Clear directions for random lasers." Nature 539, 360 (2016).

18:30  19:30

Dinner

19:30  21:00

Poster session
