# Dr Marian Florescu

+44 (0)1483 686813
26 ATI 02

Department of Physics, Advanced Technology Institute.

### Biography

Marian Florescu joined the University of Surrey in 2011. He graduated from the University of Bucharest with a BSc in Physics and then obtained his PhD in Theoretical Quantum Optics at the University of Toronto. Prior to joining the Physics Department at Surrey he was a Research Scholar and Lecturer at Princeton University and a National Research Council Research Associate at NASA Jet Propulsion Laboratory. His current activities are focused on the physics and applications of non-crystallographic photonic band gap materials, thermal radiation control in photonic materials and quantum optics in structured photonic reservoirs.

Please see my homepage above for further details of my research.

### Research interests

MICRO- AND NANO-PHOTONICS

• Fundamentals and applications of non-crystallographic photonic structures
• Thermal radiation in nano-structured photonic materials; thermal management and thermophotovoltaic energy conversion
• Quantum nonlinear optics and all-optical information processing in micro-structured photonic materials
• Physics of structural colours in biophotonic nanostructures

NANO-ELECTRONICS AND SPINTRONICS

• Temperature insensitive semiconductor materials: electronic structure and loss mechanisms in dilute bismide and nitride alloys
• Hyperuniform disordered 2D and 3D electronic systems: amorphous graphene and silicon models
• Flux quantization in disordered superconducting networks

LINEAR OPTICAL QUANTUM COMPUTING IN PHOTONIC NANOSTRUCTURES

• Single-photon sources and detectors
• Cavity-mediated entanglement of photonic and electronic excitations

### Research collaborations

• Imperial College London
• University of Southampton
• San Francisco State University
• Princeton University
• New York University
• Humboldt University
• Etaphase Inc.

### Teaching

• Level M: PHYM061 Advanced Nanophotonics
• Level HE3: PHY3042 Modern Computational Techniques
• Level HE3: PHY3046 Nanophotonics and its Applications
• Level HE2: PHY2072 Light Lab
• Level HE2: PHY2065 Electromagnetic Waves

### Departmental duties

• Director of Research Physics Department
• Head Theory and Computation Group
• Level 1 Coordinator
• Member of the Board of Studies Sub-Committee
• Member of Staff Student Liaison Committee
• Departmental Representative Additional Learning Support

### Publications

Gkantzounis Georgios, Amoah Timothy, Florescu Marian (2017) Physical Review B 95 (9) 094120 American Physical Society
We demonstrate the existence of large phononic band gaps in designed hyperuniform (isotropic) disordered two-dimensional (2D) phononic structures of Pb cylinders in epoxy matrix. The phononic band gaps in hyperuniform disordered phononic structures are comparable to band gaps of similar periodic structures, for both out-of-plane and in-plane polarizations. A large number of localized modes is identi ed near the band edges, as well as, di usive transmission throughout the rest of the frequency spectrum. Very high-Q cavity modes for both out-of-plane and in-plane polarizations are formed by selectively removing a single cylinder out of the structure. E cient waveguiding with almost 100% transmission trough waveguide structures with arbitrary bends is also presented. We expand our results to thin three-dimensional layers of such structures and demonstrate e ective band gaps related to the respective 2D band gaps. Moreover, the drop in the Q factor for the three-dimensional structures is not more than three orders of magnitude compared to the 2D ones.
Florescu M, Lee H, Stimpson AJ, Dowling J (2005) PHYSICAL REVIEW A 72 (3) ARTN 033821 AMERICAN PHYSICAL SOC
Florescu M, Amoah T (2015) Physical Review B: Condensed Matter and Materials Physics 91 pp. 020201-1-020201-5 American Physical Society
MilosÇevic MM, Florescu M, Man W, Steinhardt PJ, Torquato S, Chaikin PM, Amoah T, Nahal G, Mullen RA (2014) Optical Fiber Communication Conference, OFC 2014
We report preliminary results for silicon waveguides and devices in hyperuniform disordered photonic solids. Temperature sensitivity of resonant defects is more than 500 times lower than that of the standard silicon microring resonators. © 2013 Optical Society of America.
Florescu M, Torquato S, Steinhardt PJ (2009) PHYSICAL REVIEW B 80 (15) ARTN 155112 AMER PHYSICAL SOC
Florescu M, Scheel S, Haeffner H, Lee H, Strekalov DV, Knight PL, Dowling JP (2002) Single photons on demand from 3D photonic band-gap structures, Europhysics Letterrs 69
We describe a practical implementation of a (semi-deterministic) photon gun
based on stimulated Raman adiabatic passage pumping and the strong enhancement
of the photonic density of states in a photonic band-gap material. We show that
this device allows {\em deterministic} and {\em unidirectional} production of
single photons with a high repetition rate of the order of 100kHz. We also
discuss specific 3D photonic microstructure architectures in which our model
can be realized and the feasibility of implementing such a device using
${Er}^{3+}$ ions that produce single photons at the telecommunication
wavelength of $1.55 \mu$m.
Geev N, Man W, Florescu M, Steinhardt P, Torquato S, Chaikin P, Mullen RA New designer dielectric metamaterial with isotropic photonic band gap, (480)
Florescu M, John S (2002) APPLICATIONS OF PHOTONIC TECHNOLOGY 5 4833 pp. 513-524 SPIE-INT SOC OPTICAL ENGINEERING
Florescu M, Busch K (2009) Properties of thermal radiation in photonic crystals, JOURNAL OF OPTICS A-PURE AND APPLIED OPTICS 11 (11) IOP PUBLISHING LTD
Florescu M, Steinhardt PJ, Torquato S
Schuler CJ, Wolff C, Busch K, Florescu M (2010) ACTIVE PHOTONIC MATERIALS III 7756 SPIE-INT SOC OPTICAL ENGINEERING
John S, Florescu M (2001) Photonic bandgap materials: towards an all-optical micro-transistor, JOURNAL OF OPTICS A-PURE AND APPLIED OPTICS 3 (6) pp. S103-S120 IOP PUBLISHING LTD
Florescu M, John S (2004) Physical Review A - Atomic, Molecular, and Optical Physics 69 (5 B) pp. 053810-1
Bushell Z, Florescu M, Sweeney SJ University of Surrey
Florescu M, Dickman S, Ciorga M, Sachrajda A, Hawrylak P (2004) Spin-orbit interaction and spin relaxation in a lateral quantum dot, PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES 22 (1-3) pp. 414-417 ELSEVIER SCIENCE BV
Scheel S, Florescu M, Haffner H, Lee H, Strekalov DV, Knight PL, Dowling JP (2007) Single photons on demand from tunable 3D photonic band-gap structures, JOURNAL OF MODERN OPTICS 54 (2-3) pp. 409-416 TAYLOR & FRANCIS LTD
Milosevic M, Florescu M, Man W, Nahal G, Tsitrin S, Amoah T, Steinhardt PJ, Torquato S, Mullen RA (2014) Hyperuniform disordered photonic band gap silicon devices for optical interconnects, Optical Interconnects Conference, 2014 IEEE
Florescu M University of Surrey
Florescu M, Steinhardt PJ, Torquato S (2013) Erratum: Optical cavities and waveguides in hyperuniform disordered photonic solids (Physical Review B (2013) 87 (165116) DOI:10.1103/PhysRevB.87.165116), Physical Review B - Condensed Matter and Materials Physics 87 (15)
Amoah T, Florescu M (2015) Flexible cavity and waveguide light confinement in hyperuniform photonic slabs, Optical Sensors, Sensors 2015
We introduce novel planar hyperuniform-disordered (HUD) architectures as potential general-purpose platform for optical microcircuits. Efficient confinement of TE-polarized radiation and high-Q optical-cavities and low-loss waveguides is demonstrated using finite difference-time-domain and band-structure simulations. © 2015 Optical Society of America.
Maspero R, Sweeney SJ, Florescu M (2013) Modelling the Auger Recombination rates of GaAs(1-x)Bi x alloys, 13th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD 2013 pp. 81-82
We calculate the Conduction, Heavy Hole (HH) - Split-off Hole (SO), HH (CHSH) Auger Recombination rates for GaAs(1-x)Bix alloys, which are candidates for highly efficient telecommunication devices. A ten-band, tight-binding method, including spin-orbit coupling, was performed on a 9×9×9 strained supercell in order to generate an accurate band structure to perform the calculation on. This band structure was then unfolded to give a true E-k relation. As predicted by experiment, there should be a decrease in the Auger recombination rate as the concentration of Bismuth increases ending in a suppression at greater than
Florescu M, Torquato S, Steinhardt PJ (2009) New classes of non-crystalline photonic band gap materials, Proccedings of The European Conference on Lasers and Electro-Optics and the XIth European Quantum Electronics Conference
Spedalieri FM, Lee H, Florescu M, Kapale KT, Yurtsever U, Dowling JP (2004) Exploiting the quantum Zeno effect to beat photon loss in linear optical
quantum information processors,
Optics Communications
We devise a new technique to enhance transmission of quantum information
through linear optical quantum information processors. The idea is based on
applying the Quantum Zeno effect to the process of photon absorption. By
frequently monitoring the presence of the photon through a QND (quantum
non-demolition) measurement the absorption is suppressed. Quantum information
is encoded in the polarization degrees of freedom and is therefore not affected
by the measurement. Some implementations of the QND measurement are proposed.
Wache R, Florescu M, Sweeney SJ, Clowes SK (2015) Selectively reflective transparent sheets, ACTIVE PHOTONIC MATERIALS VII 9546 SPIE-INT SOC OPTICAL ENGINEERING
Florescu M, Busch K, Dowling JP (2007) PHYSICAL REVIEW B 75 (20) ARTN 201101 AMERICAN PHYSICAL SOC
Florescu M, Hawrylak P (2006) PHYSICAL REVIEW B 73 (4) ARTN 045304 AMER PHYSICAL SOC
Florescu M, Torquato S, Steinhardt PJ (2009) Designer disordered materials with large, complete photonic band gaps., Proc Natl Acad Sci U S A 106 (49) pp. 20658-20663
We present designs of 2D, isotropic, disordered, photonic materials of arbitrary size with complete band gaps blocking all directions and polarizations. The designs with the largest band gaps are obtained by a constrained optimization method that starts from a hyperuniform disordered point pattern, an array of points whose number variance within a spherical sampling window grows more slowly than the volume. We argue that hyperuniformity, combined with uniform local topology and short-range geometric order, can explain how complete photonic band gaps are possible without long-range translational order. We note the ramifications for electronic and phononic band gaps in disordered materials.
Florescu M, Torquato S, Steinhardt P (2012) Frontiers in Optics 2012/Laser Science XXVIII, OSA Technical Digest (online) Optical Society of America
We demonstrate that hyperuniform disordered structures support electromagnetic states
with very different transport properties, ranging from Bloch-like modes to diffusive states with characteristic time scales almost two-orders of magnitude larger.
Amoah T, Florescu M (2015) Flexible cavity andwaveguide light confinement in hyperuniform photonic slabs, Integrated Photonics Research, Silicon and Nanophotonics, IPRSN 2015
We introduce novel planar hyperuniform-disordered (HUD) architectures as potential general-purpose platform for optical microcircuits. Efficient confinement of TE-polarized radiation and high-Q optical-cavities and low-loss waveguides is demonstrated using finite difference-time-domain and band-structure simulations. © 2015 Optical Society of America.
Florescu M, Steinhardt PJ, Torquato S (2013) Physical Review B - Condensed Matter and Materials Physics 87 (16)
Amoah T, Florescu M (2015) Flexible cavity and waveguide light confinement in hyperuniform photonic slabs, Photonic Networks and Devices, Networks 2015
We introduce novel planar hyperuniform-disordered (HUD) architectures as potential general-purpose platform for optical microcircuits. Efficient confinement of TE-polarized radiation and high-Q optical-cavities and low-loss waveguides is demonstrated using finite difference-time-domain and band-structure simulations. © 2015 Optical Society of America.
Florescu M, Dowling J, Lee H (2009) US/20090217977 A1
Amoah T, Florescu M (2015) Hyperuniform photonic slabs for high-Q cavities and low-loss waveguides, ACTIVE PHOTONIC MATERIALS VII 9546
Florescu M, Lee H, Dowling JP (2005) On the emission and absorption of thermal radiation in photonic crystals, Optics InfoBase Conference Papers
We investigate the general features of thermal emission and absorption of radiation in photonic crystals. The light-matter interaction is strongly affected by the presence of the three-dimensional photonic crystal and the alteration of the photonic density of states can be used to suppress or enhance the thermal emissivity and absorptivity of the dielectric structure. Our analysis shows that the thermal response of the system depends on both the elementary absorbers/emitters and the photonic reservoir characteristics. In particular, we demonstrate that, depending on the system configuration, the thermal emission may exceed the free-space radiative energy density given by Planck's law. This modification of the Planck's law is achieved without altering the optical properties of the absorber/emitter medium, which remain consistent with the usual definition of a frequency and angle dependent grey-body. We also evaluate the rate of spontaneous emission, stimulated emission and absorption for thermally driven two-level atomic systems in a photonic crystal, and introduce effective A and B coefficients for the case of a photonic crystal. © 2005 OSA/FIO.
Man WN, Florescu Marian, Matsuyama K, Yadak P, Torquato S, Steinhardt P, Chaikin P (2010) 2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS) IEEE
Amoah T, Florescu M (2015) Flexible cavity and waveguide light confinement in hyperuniform photonic slabs, Novel Optical Materials and Applications, NOMA 2015
We introduce novel planar hyperuniform-disordered (HUD) architectures as potential general-purpose platform for optical microcircuits. Efficient confinement of TE-polarized radiation and high-Q optical-cavities and low-loss waveguides is demonstrated using finite difference-time-domain and band-structure simulations. © 2015 Optical Society of America.
Florescu M, Scheel S, Lee H, Knight PL, Bowling JP (2006) Three-dimensional photonic band-gap structures for single-photon on demand sources, ICTON 2006: 8th International Conference on Transparent Optical Networks, Vol 2, Proceedings pp. 40-43 IEEE
Milosevic MM, Florescu M, Man W, Nahal G, Tsitrin S, Amoah T, Steinhardt PJ, Torquato S, Chaikin PM, Mullen RA (2014) 2014 IEEE 11TH INTERNATIONAL CONFERENCE ON GROUP IV PHOTONICS (GFP) pp. 33-34 IEEE
© 2014 IEEE.We report experimental and simulation results for silicon waveguides and resonant cavities in hyperuniform disordered photonic solids. Our results demonstrate the ability of disordered photonic bandgap materials to serve as a platform for silicon photonics.
Amoah T, Florescu M University of Surrey
Miloaevi? MM, Florescu M, Amoah T, Man W, Nahal G, Steinhardt PJ, Torquato S, Chaikin PM, Mullen RA (2014) Optics InfoBase Conference Papers
We report preliminary results for silicon waveguides and devices in hyperuniform disordered photonic solids. Temperature sensitivity of resonant defects is more than 500 times lower than that of the standard silicon microring resonators. © 2013 Optical Society of America.
Man W, Florescu M, Matsuyama M, Yadak P, Nahal G, Hamshezad S, Williamson E, Steinhardt P, Torquato S, Chaikin P (2013) Optics Express 21 (17) pp. 19972-19981
Tsitrin S, Nahal G, Man W, Florescu M, Miloaevi? MM, Mullen RA, Steinhardt P, Torquato S, Chaikin P (2014) Fabrication and optimization for waveguides in sub-micron scale hyperuniform disordered photonic bandgap materials, Optics InfoBase Conference Papers
We report experimental and simulation results for low-loss wave-guiding in Si-based hyperuniform disordered photonic bandgap materials at infrared wavelengths. These results pave the way for deploying disordered photonic solids in integrated photonic circuits. © 2014 Optical Society of America.
Florescu M, Man W, Mullen RA, Milosevic M, Amoah T, Chaikin PM, Torquato S, Steinhardt P (2014) Isotropic band gaps, optical cavities, and freeform waveguides in hyperuniform disordered photonic solids, Proc. SPIE 9162, Active Photonic Materials VI, 91620G (September 12, 2014)
Amoah T, Florescu M (2015) Light confinement in hyperuniform photonic slabs: High-Q cavities and low-loss waveguides, CLEO: Science and Innovations, CLEO-SI 2015
Using finite-difference-time-domain and band-structure simulations, we demonstrate efficient confinement of TE-polarized radiation and high-Q optical-cavities and low-loss waveguides in planar hyperuniform-disordered (HUD) architectures based on a design strategy that has potential to be a general purpose platform for optical microcircuits. © OSA 2015.
Florescu M, Tsitrin S, Williamson E, Amoah T, Nahal G, Chan L, Man W (2015) Scientific Reports 5 13301 pp. 1-8 Nature Publishing Group
Florescu M, John S (2001) Physical Review A. Atomic, Molecular, and Optical Physics 64 (3) pp. 033801/1-033801/21 American Physical Society
Florescu M, Lee H, Puscasu I, Pralle M, Florescu L, Ting DZ, Dowling JP (2007) Improving solar cell efficiency using photonic band-gap materials, SOLAR ENERGY MATERIALS AND SOLAR CELLS 91 (17) pp. 1599-1610 ELSEVIER SCIENCE BV
Amoah T, Florescu M (2015) Flexible cavity and waveguide light confinement in hyperuniform photonic slabs, Signal Processing in Photonic Communications, SPPCom 2015
We introduce novel planar hyperuniform-disordered (HUD) architectures as potential general-purpose platform for optical microcircuits. Efficient confinement of TE-polarized radiation and high-Q optical-cavities and low-loss waveguides is demonstrated using finite difference-time-domain and band-structure simulations. © 2015 Optical Society of America.
Florescu M, Torquato S, Steinhardt PJ (2009) New classes of non-crystalline photonic band gap materials, Optics InfoBase Conference Papers
Florescu M, Sellers S Local Self-Uniformity in Photonic Networks, University of Surrey
Tsitrin S, He Y, Hewatt S, Leung B, Man W, Florescu M, Steinhardt PJ, Torquato S, Chaikin P (2012) Frontiers in Optics 2012/Laser Science XXVIII, OSA Technical Digest (online) Optical Society of America
photonic band gap material. We demonstrate that point-like defects can support localized
modes with different symmetries and multiple resonant frequencies, useful for various
applications.
Schuler CJ, Wolff C, Busch K, Florescu M (2009) APPLIED PHYSICS LETTERS 95 (24) ARTN 241103 AMER INST PHYSICS
Man W, Florescu M, Williamson EP, He Y, Hashemizad SR, Leung BY, Liner DR, Torquato S, Chaikin P, Steinhardt PJ (2013) Isotropic band gaps and freeform waveguides observed in hyperuniform disordered photonic solids, Proceedings of the National Academy of Sciences of USA 120 (40) pp. 15886-15891
Miloaevi? MM, Florescu M, Man W, Steinhardt PJ, Torquato S, Chaikin PM, Amoah T, Nahal G, Mullen RA (2014) Conference on Optical Fiber Communication, Technical Digest Series
We report preliminary results for silicon waveguides and devices in hyperuniform disordered photonic solids. Temperature sensitivity of resonant defects is more than 500 times lower than that of the standard silicon microring resonators. © 2014 OSA.
Man W, He Y, Leung R, Tsitrin S, Florescu M, Steinhardt PJ, Torquato S, Chaikin P (2012)
Florescu M, Steinhardt PJ, Torquato S Narrow-band frequency filters and splitters, photonic sensors, and cavities having pre-selected cavity modes,
Waveguides and electromagnetic cavities fabricated in hypemniform disordered materials with complete photonic bandgaps are provided. Devices comprising electromagnetic cavities fabricated in hypemniform disordered materials with complete photonic bandgaps are provided. Devices comprising waveguides fabricated in hypemniform disordered materials with complete photonic bandgaps are provided. The devices include electromagnetic splitters, filters, and sensors.
Nahal G, Florescu M, Mullen RA, Steinhardt P, Torquato S, Chaikin P, Man W (2013) Freeform wave-guiding at infrared regime in two dimensional disordered photonic bandgap materials, Optics InfoBase Conference Papers
We report the first experimental demonstration of guiding, bending and power-splitting of light in 2D disordered photonic bandgap materials at infrared wavelengths, along curved paths, around sharp bends of arbitrary angles, and through Y-shape junctions. © 2013 Optical Society of America.
Castro-Lopez M, Gaio M, Sellers Steven, Gkantzounis Georgios, Florescu Marian, Sapienza R (2017) APL Photonics 2 (6) 061302 AIP Publishing LLC
Hyperuniform geometries feature correlated disordered topologies which follow
from a tailored k-space design. Here, we study gold plasmonic hyperuniform
disordered surfaces and, by momentum spectroscopy, we report evidence of kspace
engineering on both light scattering and light emission. Even if the structures
lack a well-defined periodicity, emission and scattering are directional in
ring-shaped patterns. The opening of these rotational-symmetric patterns scales
with the hyperuniform correlation length parameter as predicted via the spectral
function method.
Bushell Z, Florescu M, Sweeney S (2017) Physical Review B 95 (23) 235303 American Physical Society
Photonic crystal cavities enable the realization of high Q-factor and low mode-volume resonators, with typical architectures consisting of a thin suspended periodically patterned layer to maximize confinement of light by strong index guiding. We investigate a heterostructure-based approach comprising a high refractive index core and lower refractive index cladding layers. While confinement typically decreases with decreasing index contrast between the core and cladding layers, we show that, counterintuitively, due to the confinement provided by the photonic band structure in the cladding layers, it becomes possible to achieve Q factors
>
10
4
with only a small refractive index contrast. This opens up opportunities for implementing high-Q factor cavities in conventional semiconductor heterostructures, with direct applications to the design of electrically pumped nanocavity lasers using conventional fabrication approaches.
Utgenannt A, Maspero Ross, Fortini Andrea, Turner R, Florescu Marian, Jeynes Christopher, Kanaras AG, Muskens OL, Sear Richard, Keddie Joseph (2016) ACS Nano 10 (2) pp. 2232-2242 American Chemical Society
When fabricating photonic crystals from suspensions in volatile liquids using the horizontal deposition method, the conventional approach is to evaporate slowly to increase the time for particles to settle in an ordered, periodic close-packed structure. Here, we show that the greatest ordering of 10 nm aqueous gold nanoparticles (AuNPs) in a template of larger spherical polymer particles (mean diameter of 338 nm) is achieved with very fast water evaporation rates obtained with near-infrared radiative heating. Fabrication of arrays over areas of a few cm2 takes only seven minutes. The assembly process requires that the evaporation rate is fast relative to the particles? Brownian diffusion. Then a two-dimensional colloidal crystal forms at the falling surface, which acts as a sieve through which the AuNPs pass, according to our Langevin dynamics computer simulations. With sufficiently fast evaporation rates, we create a hybrid structure consisting of a two-dimensional AuNP nanoarray (or ?nanogrid?) on top of a three-dimensional polymer opal. The process is simple, fast and one-step. The interplay between the optical response of the plasmonic Au nanoarray and the microstructuring of the photonic opal results in unusual optical spectra with two extinction peaks, which are analyzed via finite-difference time-domain method simulations. Comparison between experimental and modelling results reveals a strong interplay of plasmonic modes and collective photonic effects, including the formation of a high-order stop band and slow-light enhanced plasmonic absorption. The structures, and hence their optical signatures, are tuned by adjusting the evaporation rate via the infrared power density.
Florescu Marian, Torquato S, Steinhardt PJ (2010) APPLIED PHYSICS LETTERS 97 (20) 201103 AMER INST PHYSICS
Maspero Ross, Sweeney Stephen, Florescu Marian (2016) Journal of Physics: Condensed Matter 29 (7) 075001 Institute of Physics
Typical supercell approaches used to investigate the electronic properties of GaAs(1?x)Bi(x) produce highly accurate, but folded, band structures. Using a highly optimized algorithm, we unfold the band structure to an approximate $E\left(\mathbf{k}\right)$ relation associated with an effective Brillouin zone. The dispersion relations we generate correlate strongly with experimental results, confirming that a regime of band gap energy greater than the spin?orbit-splitting energy is reached at around 10% bismuth fraction. We also demonstrate the effectiveness of the unfolding algorithm throughout the Brillouin zone (BZ), which is key to enabling transition rate calculations, such as Auger recombination rates. Finally, we show the effect of disorder on the effective masses and identify approximate values for the effective mass of the conduction band and valence bands for bismuth concentrations from 0?12%.
Sellers Steven, Man W, Sahba S, Florescu Marian (2017) Nature Communications 8 14439 Nature Publishing Group
The interaction of a material with light is intimately related to its wavelength-scale structure. Simple connections between structure and optical response empower us with essential intuition to engineer complex optical functionalities. Here we develop local self-uniformity as a novel measure of a random network?s internal structural similarity, ranking networks on a continuous scale from crystalline, through glassy intermediate states, to chaotic configurations. We demonstrate that complete photonic band gap structures possess substantial local selfuniformity and validate local self-uniformity?s importance in gap formation through design of novel amorphous gyroid structures. Amorphous gyroid samples are fabricated via 3D ceramic printing and the band gaps experimentally verified. We explore also the wing-scale structuring in the butterfly Pseudolycaena marsyas and show that it possesses substantial amorphous gyroid character, demonstrating the subtle order achieved by evolutionary optimisation and the possibility of an amorphous gyroid?s self-assembly.
Florescu Marian, Scheel S, Lee H, Knight PL, Dowling JP (2006) PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES 32 (1-2) pp. 484-487 Elsevier
Florescu Marian, Scheel S, Knight PL, Lee H, Dowling JP (2006) Physica E: Low-Dimensional Systems and Nanostructures 32 (1-2 SP) pp. 484-487 Elsevier
We describe a practical implementation of a semi-deterministic photon gun based on the stimulated Raman adiabatic passage pumping and the nonlinear tuning of the photonic density of states in a photonic band-gap material. We show that this device allows deterministic and unidirectional production of single photons with a high repetition rate of the order of 100 kHz. We also discuss specific 3D photonic microstructure architectures in which our model can be realized and the feasibility of implementing such a device using Er ions that produce single photons at the telecommunication wavelength of 1.55 ¼ m. © 2006 Elsevier B.V. All rights reserved.
Man W, Florescu Marian, Hashemizad S, He Y, Leung R, Williamson E, Chaikin P (2012) Conference on Lasers and Electro-Optics 2012, OSA Technical Digest
We report the first experimental demonstration of guiding, bending, filtering, and splitting of EM wave in 2D disordered PBG materials, along arbitrarily curved paths, around sharp bends of arbitrary angles, and through Y shape junctions. © 2012 OSA.
Florescu Marian (2018) University of Surrey
Gkantzounis Georgios, Florescu Marian (2017) Crystals 7 (12)
We employ a recently introduced class of artificial structurally-disordered phononic structures that exhibit large and robust elastic frequency band gaps for efficient phonon guiding. Phononic crystals are periodic structures that prohibit the propagation of elastic waves through destructive interference and exhibit large band gaps and ballistic propagation of elastic waves in the permitted frequency ranges. In contrast, random-structured materials do not exhibit band gaps and favour localization or diffusive propagation. Here, we use structures with correlated disorder constructed from the so-called stealthy hyperuniform disordered point patterns, which can smoothly vary from completely random to periodic (full order) by adjusting a single parameter. Such amorphous-like structures exhibit large band gaps (comparable to the periodic ones), both ballistic-like and diffusive propagation of elastic waves, and a large number of localized modes near the band edges. The presence of large elastic band gaps allows the creation of waveguides in hyperuniform materials, and we analyse various waveguide architectures displaying nearly 100% transmission in the GHz regime. Such phononic-circuit architectures are expected to have a direct impact on integrated micro-electro-mechanical filters and modulators for wireless communications and acousto-optical sensing applications.
Florescu Marian (2016) university of surrey
Maspero Ross University of Surrey
Florescu M (2016) university of surrey
Florescu Marian University of Surrey
Maspero Ross (2017)
In this thesis, we develop a generalised unfolding formalism to investigate the electronic and photonic properties of aperiodically-structured materials. We initially focus on GaAsBi alloys for electronic systems and Penrose-structured materials for photonic systems, aperiodic materials that cannot be easily studied using conventional band structure methods. We then extend our study to the supercell approach which facilitates an accurate modelling of the aperiodic structures at the price of obscuring essential physical information, due to a band folding effect. Then introducing a generalised unfolding algorithm, we return the supercell band structure to a traditional form that can again be used to analyse the electronic and photonic properties of the system.

GaAsBi, which is a material with the potential to suppress the dominant loss mechanisms in telecommunications devices, was studied using the unfolded supercell band structure approach. We investigated the effect of bismuth on the properties of a host GaAs structure, including band movement, band broadening and effective mass. We validated our approach through a detailed comparison of both band movement and effective masses to the currently available experimental data. Then, we introduced a formalism for calculating the CHSH Auger recombination rates from our unfolded band structure, which will assist in determining the efficiency of the material.

Quasicrystalline photonic materials built on the skeleton of Penrose lattices have proven to display photonic properties comparable to the ones found in photonic crystals, but with the added promise of increased isotropy. The photonic band structure of these materials is a prime target for the unfolding formalism because it allows a full exploration of the influence of the increased geometrical symmetry on their photonic characteristics. Furthermore, the network structure investigated demonstrated the existence of a sub-fundamental photonic band gap, a characteristic unique to quasicrystalline structures. The unfolded band structure enabled the investigation of the mechanisms responsible for the formation of this peculiar band gap.

Finally, we depart from the frequency domain approach and employ time domain simulations to investigate the photonic and plasmonic properties of a hybrid structure consisting of a polymer based opal with a quasi-2D gold nanoparticle grid on the surface. The optical response of the structure displays an intricate interplay between the plasmonic resonances and the photonic stop band effects. Adopting a renormalised Maxwell-Garnett effective index for describing the gold nanogrid, we successfully elucidate the main physical mechanisms governing the optical response of these structures in good agreement with the results of experimental investigations.

Miloaevi? Milan M., Man Weining, Nahal Geev, Steinhardt Paul J., Torquato Salvatore, Chaikin Paul M., Amoah Timoth, Yu Bowen, Mullen Ruth Ann, Florescu Marian (2019) Scientific Reports 9 (1) 20338 Nature Publishing Group
We introduce a hyperuniform-disordered platform for the realization of near-infrared photonic
devices on a silicon-on-insulator platform, demonstrating the functionality of these structures in a
fexible silicon photonics integrated circuit platform unconstrained by crystalline symmetries. The
designs proposed advantageously leverage the large, complete, and isotropic photonic band gaps
provided by hyperuniform disordered structures. An integrated design for a compact, sub-volt, sub-fJ/
bit, hyperuniform-clad, electrically controlled resonant optical modulator suitable for fabrication
in the silicon photonics ecosystem is presented along with simulation results. We also report results
for passive device elements, including waveguides and resonators, which are seamlessly integrated
with conventional silicon-on-insulator strip waveguides and vertical couplers. We show that the
hyperuniform-disordered platform enables improved compactness, enhanced energy efciency,
and better temperature stability compared to the silicon photonics devices based on rib and strip
waveguides.
Jurewicz Izabela, King Alice A.K, Shanker Ravi, Large Matthew J., Smith Roman J., Maspero Ross, Ogilvie Sean P., Scheerder Jurgen, Han Jun, Backes Claudia, Razal Joe, Florescu Marian, Keddie Joseph, Coleman Jonathan N., Dalton Alan (2020) Advanced Functional Materials 30 (31) Wiley
High quality opal-like photonic crystals containing graphene are fabricated using evaporation-driven self-assembly of soft polymer colloids. A miniscule amount of pristine graphene within a colloidal crystal lattice results in the formation of colloidal crystals with a strong angle-dependent structural color and a stop band that can be reversibly shifted across the visible spectrum. The crystals can be mechanically deformed or can reversibly change color as a function of their temperature, hence their sensitive mechanochromic and thermochromic response make them attractive candidates for a wide range of visual sensing applications. In particular, we show that the crystals are excellent candidates for visual strain sensors or integrated time-temperature indicators which act over large temperature windows. Given the versatility of these crystals, this method represents a simple, inexpensive and scalable approach to produce multifunctional graphene infused synthetic opals and opens up exciting applications for novel solution-processable nanomaterial based photonics.
Maimouni Ilham, Morvaridi Maryam, Russo Maria, Lui Gianluc, Morozov Konstantin, Cossy Janine, Florescu Marian, Labousse Matthieu, Tabeling Patrick (2020) ACS Applied Materials & Interfaces 12 (28) pp. 32061-32068 American Chemical Society
Solid foams with micrometric pores are used in different fields (filtering, 3D cell culture, etc.), but today, controlling their foam geometry at the pore level, their internal structure, and the monodispersity, along with their mechanical properties, is still a challenge. Existing attempts to create such foams suffer either from slow speed or size limitations (above 80 ¼m). In this work, by using a temperature-regulated microfluidic process, 3D solid foams with highly monodisperse open pores (PDI lower than 5%), with sizes ranging from 5 to 400 ¼m and stiffnesses spanning 2 orders of magnitude, are created for the first time. These features open the way for exciting applications, in cell culture, filtering, optics, etc. Here, the focus is set on photonics. Numerically, these foams are shown to open a 3D complete photonic bandgap, with a critical index of 2.80, thus compatible with the use of rutile TiO2. In the field of photonics, such structures represent the first physically realizable self-assembled FCC (face-centered cubic) structure that possesses this functionality.