Turing patterns and solitons are a common occurrence in systems that are out of equilibrium. For example, they regulate the emergence of organised structures in biology and chemistry. In optics, the study of temporal Turing rolls and cavity-solitons in nonlinear micro-cavity resonators has been key to the understanding of optical frequency comb formation in these structures. Over a decade, the impact of microresonator-based approaches to generating frequency combs – so-called “Micro-combs or “Kerr combs” – has reached far beyond metrology applications. Here we summarise our theoretical and experimental results for solitons and Turing patterns in a system comprising a micro-resonator nested in an auxiliary fibre-gain cavity.
Terahertz (THz) is an innovative form of electromagnetic radiation providing unique spectroscopy capabilities in critical fields, ranging from biology to material science and security. The limited availability of high-resolution imaging devices, however, constitutes a major limitation in this field. In this work, we tackle this challenge by proposing an innovative type of time-space nonlinear Ghost-Imaging (GI) methodology that conceptually outperforms established single-pixel imaging protocols. Our methodology combines nonlinear pattern generation with time-resolved single-pixel measurements, as enabled by the state-of-the-art Time-Domain Spectroscopy (TDS) technique. This approach is potentially applicable to any wave-domain in which the field is a measurable quantity. The full knowledge of the temporal evolution of the transmitted field enables devising a new form of full-wave reconstruction process. This gives access not only to the morphological features of the sample with deeply subwavelength resolution but also to its local spectrum (hyperspectral imaging). As a target application, we consider hyperspectral THz imaging of a disordered inhomogeneous sample.
K. Bongs, V. Boyer, M. Cruise, A. Freise, M. Holynski, J. Hughes, A. Kaushik, Y.-H. Lien, A. Niggebaum, M. Perea-Ortiz, P. Petrov, S. Plant, Y. Singh, A. Stabrawa, D. Paul, M. Sorel, D. R. Cumming, J. Marsh, R. Bowtell, M. Bason, R. Beardsley, R. Campion, M. Brookes, T. Fernholz, T. Fromhold, L. Hackermuller, P. Krüger, X. Li, J. Maclean, C. Mellor, S. Novikov, F. Orucevic, A. Rushforth, N. Welch, T. Benson, R. Wildman, T. Freegarde, M. Himsworth, J. Ruostekoski, P. Smith, A. Tropper, P. Griffin, A. Arnold, E. Riis, J. Hastie, D. Paboeuf, D. Parrotta, B. Garraway, A. Pasquazi, M. Peccianti, W. Hensinger, E. Potter, A. Nizamani, H. Bostock, A. Rodriguez Blanco, G. Sinuco-Leon, I. Hill, R. Williams, P. Gill, N. Hempler, G. P. Malcolm, T. Cross, B. O. Kock, S. Maddox, P. John
The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices, with game-changing miniaturized components and prototypes that transform the state-of-the-art for quantum sensors and metrology. It brings together experts from the Universities of Birmingham, Glasgow, Nottingham, Southampton, Strathclyde and Sussex, NPL and currently links to over 15 leading international academic institutions and over 70 companies to build the supply chains and routes to market needed to bring 10–1000x improvements in sensing applications. It seeks, and is open to, additional partners for new application development and creates a point of easy open access to the facilities and supply chains that it stimulates or nurtures.
Passive fiber mode-locked lasers enable the excitation of multiple pulses per round trip representing a potential solutions for the increasing demand of practical optical sources with repetition rates of hundreds of GHz or higher. The control of such high repetition rate regimes is however a challenge. To this purpose, linear filters have been used in an "intracavity" configuration to force the repetition rate of the laser. This design is known as dissipative four wave mixing (DFWM) but it is usually unstable and hence marginally suitable for practical applications. We explore the use of nonlinear intracavity filters, such as integrated micro-ring resonators, capable of “driving” the FWM interaction in the laser. We term this approach as Filter-Driven FWM. With a proper choice of the filter properties in terms of free spectral range (FSR) and Q factor, we could observe stable regimes over a wide range of operating conditions, from high repetition rate oscillation at a 200GHz to the formation of two stable spectral comb replicas separated by the FSR of the main cavity (65MHz). High order filters, moreover, allow achieving nonlinear operation over large passbands. With an 11th order filter we achieve low-frequency mode-locking between the main cavity modes that oscillate within each resonance of the filter, producing burst pulsed operation. A stable mode-locked pulse train at 655GHz with an envelope of 42ps at 6.45MHz is achieved.
Photonic integrated circuits that exploit nonlinear optics in order to generate and process signals all-optically have achieved performance far superior to that possible electronically - particularly with respect to speed. We review the recent achievements based in new CMOS-compatible platforms that are better suited than SOI for nonlinear optics, focusing on radio frequency (RF) and microwave based applications that exploit micro-resonator based frequency combs. We highlight their potential as well as the challenges to achieving practical solutions for many key applications. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement. We review recent work on a photonic RF Hilbert transformer for broadband microwave in-phase and quadrature-phase generation based on an integrated frequency optical comb. The comb is generated using a nonlinear microring resonator based on a CMOS compatible, high-index contrast, doped-silica glass platform. The high quality and large frequency spacing of the comb enables filters with up to 20 taps, allowing us to demonstrate a quadrature filter with more than a 5-octave (3 dB) bandwidth and an almost uniform phase response.
We demonstrate a range of novel functions based on a high index doped silica glass CMOS compatible platform. This platform has promise for telecommunications and onchip WDM optical interconnects for computing.
We demonstrate a wide range of novel functions in integrated, CMOS compatible, devices. This
platform has promise for telecommunications and on-chip WDM optical interconnects for computing.
The study of optical solitons and light filaments steering in liquid crystals requires utilization of particular
cells designed for top view investigation and realized with an input interface which enables both to control the
molecular director configuration and to prevent light scattering. Up to now, the director orientation imposed by
this additional interface has been only estimated by experimental observations. In this paper, we report on the
design and characterization of liquid crystal cells for investigation of optical spatial solitons as well as on a simple
model describing the configuration of the molecular director orientation under the anchoring action of multiple
interfaces. The model is based on the elastic continuum theory and only strong anchoring is considered for
boundary conditions. Controlling of the director orientation at the input interface, as well as in the bulk, allows
to obtain configurations that can produce distinct optical phenomena in a light beam propagating inside the cell.
For a particular director configuration, it is possible to produce two waves: the extraordinary and the ordinary
one. With a different director configuration, the extraordinary wave only is obtained, which propagates inside
the cell at an angle of more than 7° with respect to the impinging wave vector direction. Under this peculiar
configuration and by applying an external voltage, it is possible to have a good control of the propagation
direction of the optical spatial soliton.
We have observed, for the first to the best of our knowledge, time 2+1 dimensional spatial solitons with an Argon-ion beam in planar cells containing an undoped nematic liquid crystal. The cells provided planar anchoring for the liquid crystal molecules, with transparent electrodes for applying an external voltage across the 75µm-thick crystal. The voltage allowed to pre-orientate the director field m the prmcipal plane contammg the lmearly polarized optical field vector thereby elimmatmg the Fréedericks threshold In this regime, powers low enough to prevent thermal effects could be employed to obtam transverse localization through a local light induced mdex mcrease, trappmg the beam into a spatial soliton Self trapping as-well-as guidance of a copolarized probe at 633nm, were demonstrated at biases of 1v with 3.9 mW powers m the green at 514nm. A beam orthogonally polarized with respect to the director tilt-plane failed to produce self localization thereby confirming the reorientational nature of the phenomenon.
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