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Advancing Photonic Functionalities Advancing photonic functionalities P Professors Paul Steinhardt, Salvatore Torquato and Marian Florescu discuss hyperuniform R OFESSO materials use in the development of hyperuniform disordered solids, garnering better theoretical understanding of the physical properties of non-crystalline materials R S STEINHA without sensitive additional samples and discovered other new alignment of material, mineral phases. waveguides or cavities, R and are much less ST: Dr Frank Stillinger and I introduced the dt , sensitive to fabrication concept of Hyperuniform Matter, characterised to by unusual suppression of density fluctuations, defects – they contradict RQ conventional wisdom that in 2003. Specifically, hyperuniform point PBG requires periodicity (particle) configurations are categorised uato and anisotropy. Enabling by vanishing infinite-wavelength density freeform circuit design fluctuations and encompass all crystals, & and a reduction in defects quasicrystals and special disordered many- flo To begin, could you outline your role within makes them the optimal material for virtually particle systems. This provides a means to place R this project? any photonic application. These discoveries have an umbrella over both crystalline and special ESCU been enabled by the invention of a universal non-crystalline materials. HUDS can loosely PS: I am a theoretical physicist in the protocol for mapping point patterns into be regarded as a state that is intermediate Department of Physics and Department of optimal designs. between perfect crystals and perfectly Astrophysics, Princeton University, and Director disordered materials. In 2008, we showed that of the Princeton Center for Theoretical Science. What was the overall outcome? stealthy HUDS can be created as disordered One of my longstanding interests is in the ground states and possess novel single- structure and properties of non-crystalline PS, ST & MF: We showed that it’s possible scattering properties, suggesting they may find states of matter because their properties are to introduce waveguides in HUDS that can applications in photonics. still poorly understood and, hence, have the have arbitrary shape and trap light in cavities potential for exhibiting surprising features. with select electromagnetic patterns. After MF: I have been involved in the early studies discovering these novelties, both theoretically of quantum optical effects in photonic band ST: As a theoretician in the Department and numerically, we joined with experimental gap materials, while working in the group of of Chemistry, Department of Physics, and Professors Weining Man and Paul Chaikin to Professor Sajeev John, one of the inventors Princeton Institute for the Science and synthesise and test HUDS on the microwave- of the photonic crystal concept. My work on Technology of Materials, my scientific research and infrared-scale. quantum optical effects in photonic crystals covers statistical mechanics, condensed matter, revealed coherent all-optical switching and photonics and cancer modelling. Amorphous Can you provide some insight into your transistor action in PGB materials. Subsequently, states of matter have always intrigued me; research area? I developed the first general formalism for especially a new class called hyperuniform thermal emission in microstructured photonic materials (HM). PS: In 1984, Professor Dov Levine and I systems, which provides a comprehensive introduced the concept of quasicrystals, understanding of Planck’s radiation law MF: I am a physicist in the Department of hypothetical solids with long-range modifications in these systems, rigorous design Physics and the Advanced Technology Institute, quasiperiodic translational order and rotational principles for spectral and angular-selective University of Surrey. My research interests lie symmetries that are forbidden for periodic absorbers and highly efficient solar cell and in the fields of nanophotonics, quantum optics, solids. Independently, Professor Dan Shechtman thermophotovoltaic components. and nanoelectronics. In particular, I focus on and his collaborators found aluminium and the identification of novel phenomena and manganese alloys that we identified as Do you have plans to extend R&D? functionalities in artificially structured photonic matching the predicted diffraction pattern for materials and in implementations of linear- an icosahedral quasicrystal. In 2011, Shechtman PS, ST & MF: We have partnered with optical quantum information processing in won the Nobel Prize in Chemistry for his industry to create a start-up company, nanostructured materials. experimental discovery. I have since worked Etaphase Inc, that will develop our scientific with various scientists to explore mathematical discoveries into a range of products, including What novel properties have you unearthed and elastic properties of quasicrystals. In 1998, novel photonic integrated circuits for use in about photonic band gaps (PBG)? I launched a systematic search for natural computer datacenters, sensors, improved quasicrystals that culminated in the discovery photovoltaics and displays. With an eye to PS, ST & MF: Motivated by work on disordered 11 years later of quasicrystalline grains in a potential end uses, we hope to continue both HM, we discovered a new class of photonic CV3 carbonaceous chondrite that formed basic science and applicationww and develop materials, known as hyperuniform disordered 4.5 bn years ago, making quasicrystals one of better theoretical understanding of PBG and solids (HUDS). Disordered and isotropic the first solids to form in our solar system. I other physical properties of HUDS. The path is – meaning they can be used in photonic subsequently led a geological expedition to full of challenges, but we do not foresee any integrated circuits and other applications Kamchatka, where we successfully recovered showstoppers at this point. WWW.RESEARCHMEDIA.EU 143 PROFESSORS STEINHARdt, toRQuato & floRESCU Unlocking the potential of HUDS Physicists at Princeton University use novel computational tools and employ proven fabricating methods to discover the broader electronic and photonic applications of a new class of materials PHOTONIC BANDGAP (PBG) materials are The group has been developing two classes In an effort to find the optimal design of these synthetically designed materials that block light of novel non-crystalline designer materials, quasicrystals, Steinhardt joined with theorists for a finite band of energies and then transmit composed of photonic quasicrystals and Professor Salvatore Torquato, an expert on light with energies outside that band, similar hyperuniform disordered solids (HUDS), which hyperuniform materials and optimisation to the way in which a semiconductor acts for act as a photonic semiconductor. Principal problems, and photonics expert Florescu. Their electrons. The development of PBG materials is Investigator, Professor Paul Steinhardt, explains research led them to challenge the conventional seen as increasingly vital in the replacement of that their work has expanded the traditional view that periodicity or quasiperiodicity is electronics (electron transport) with photonics view of PBG materials by showing that HUDS, required to have a complete PBG. In doing so (light transport), which is necessary to realise whilst isotropic and with no translational order, they found that it is, in fact, possible to obtain the next generation of communications and have large and complete band gaps for both large complete band gaps in a new form of computer devices, as well as improved sensors, polarisations of light; a result which “contradicts material that is isotropic and disordered like LEDs, display devices and photovoltaics. the longstanding conventional wisdom that glass but also ‘hyperuniform’ like crystal. only crystalline materials have PBG”. He adds: The concept of hyperuniformity had been In order to control and manipulate light flow, “As photonic crystals are inherently anisotropic introduced and studied earlier by Torquato and specifically-designed defects can be introduced (blocking different bands of light propagating his colleague Dr Frank Stillinger. into PBG materials that make it possible to in different directions) they impose delicate transmit or trap specific frequencies within. constraints on designing photonic circuits, and “HUDS,” as Torquato expands, “have long-range Because these frequencies are far from those are also difficult to fabricate accurately”. density variations that are uniform like crystals, above and below the band gap, their behaviour even though they are isotropic”. They discovered is not degraded by mixing with modes with Because HUDS are isotropic and thus inherently that HUDS exhibit large, perfectly isotropic similar frequencies, thus enabling the ultimate disordered, they are less sensitive to fabrication band gaps, even though they are not periodic regulation of light flow. Through their invention defects and are an optimal base material which, or quasiperiodic. Since isotropy is enormously of a new form of PBG materials with unique co-PI Dr Marian Florescu (now based at Surrey advantageous in many optical applications, this symmetries and statistical properties, scientists University) suggests: “Have broad physical presented them with the opportunity to look at at Princeton University’s Department of Physics implications beyond photonic materials. It a new class of photonic solids with properties have delivered groundbreaking work with may become possible, for
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