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Photonic crystals

Matteo Morrocchi, Giovanni Ambrosi, Maria Giuseppina Bisogni, Filippo Bosi, Marco Boretto, Piergiorgio Cerello, Maria Ionica, Ben Liu, Francesco Pennazio, Maria Antonietta Piliero, Giovanni Pirrone, Vasile Postolache, Richard Wheadon, Alberto Del Guerra
BACKGROUND: Monolithic scintillators read out by arrays of photodetectors represent a promising solution to obtain high spatial resolution and the depth of interaction (DOI) of the annihilation photon. We have recently investigated a detector geometry composed of a monolithic scintillator readout on two sides by silicon photomultiplier (SiPM) arrays, and we have proposed two parameters for the DOI determination: the difference in the number of triggered SiPMs on the two sides of the detector and the difference in the maximum collected signal on a single SiPM on each side...
December 2017: EJNMMI Physics
Alberto Sinibaldi, Camilla Sampaoli, Norbert Danz, Peter Munzert, Leonardo Sibilio, Frank Sonntag, Agostino Occhicone, Elisabetta Falvo, Elisa Tremante, Patrizio Giacomini, Francesco Michelotti
We report on the use of one-dimensional photonic crystals to detect clinically relevant concentrations of ERBB2/neu/Her2 in cell lysates. ERBB2 is a pivotal breast cancer biomarker and targetable oncogenic driver associated with aggressive breast cancer subtypes. To quantitate soluble ERBB2, we developed an optical platform that combines label-free and fluorescence detection modes. Such platform makes use of a sandwich assay in which the one-dimensional photonic crystals sustaining Bloch surface waves are tailored with a monoclonal antibody for highly specific biological recognition (BSW biochip)...
February 9, 2017: Biosensors & Bioelectronics
Wang Peng, Youping Chen, Wu Ai, Dailin Zhang, Han Song, Hui Xiong, Pengcheng Huang
Photonic crystal (PC)-based devices have been widely used since 1990s, while PC has just stepped into the research area of nanofluidic. In this paper, photonic crystal had been used as a complementary metal oxide semiconductors (CMOS) compatible part to create a nanofluidic structure. A nanofluidic structure prototype had been fabricated with CMOS-compatible techniques. The nanofluidic channels were sealed by direct bonding polydimethylsiloxane (PDMS) and the periodic gratings on photonic crystal structure...
December 2017: Nanoscale Research Letters
Gregory Moille, Sylvain Combrié, Kerstin Fuchs, Matusala Yacob, Johann Peter Reithmaier, Alfredo de Rossi
We demonstrated a twofold acceleration of the fast time constant characterizing the recovery of a p-doped indium-phosphide photonic crystal all-optical gate. Time-resolved spectral analysis is compared to a three-dimensional drift-diffusion model for the carrier dynamics, demonstrating the transition from the ambipolar to the faster minority carrier dominated diffusion regime. This opens the perspective for faster yet efficient nanophotonic all-optical gates.
February 15, 2017: Optics Letters
Mohammad Khoshakhlagh, Jalil Pirayesh Islamian, Seyyed Mohammad Abedi, Babak Mahmoudian, Masoud Shayesteh Azar
BACKGROUND: Acquiring a high quality image has assigned an important concern for obtaining accurate diagnosis in nuclear medicine. Detector is a critical component of Single Photon Emission Computed Tomography (SPECT) imaging system for giving accurate information from exact pattern of radionuclide distribution in the target organ. The images are strongly affected by the attenuation, scattering, and response of the detector. The conventional detector is mainly made from sodium iodide activated by thallium [NaI(Tl)] in nuclear medicine imaging...
2017: Nuclear Medicine Review. Central & Eastern Europe
Huiru Ma, Kai Tang, Wei Luo, Lin Ma, Qian Cui, Wei Li, Jianguo Guan
Herein, we use experiments and numerical simulations to demonstrate a novel class of magnetically responsive photonic crystals (MRPCs) based on photonic nanorods which exhibit multiple optical properties in a magnetic field (H) due to their fixed photonic nanorods and H-tunable lattice defects. As an example, superparamagnetic Fe3O4@polyvinyl pyrrolidone (PVP)@SiO2 photonic nanorods were fabricated through a polyacrylic acid-catalysed hydrolysis-condensation reaction of γ-mercaptopropyltrimethoxysilane around chain-like PC templates formed by monodispersed Fe3O4@PVP particles under H...
February 15, 2017: Nanoscale
Jakub Cajzl, Pavla Nekvindová, Anna Macková, Petr Malinský, David Sedmidubský, Michal Hušák, Zdeněk Remeš, Marián Varga, Alexander Kromka, Roman Böttger, Jiří Oswald
Diamond is proposed as an extraordinary material usable in interdisciplinary fields, especially in optics and photonics. In this contribution we focus on the doping of diamond with erbium as an optically active centre. In the theoretical part of the study based on DFT simulations we have developed two Er-doped diamond structural models with 0 to 4 carbon vacancies in the vicinity of the Er atom and performed geometry optimizations by the calculation of cohesive energies and defect formation energies. The theoretical results showed an excellent agreement between the calculated and experimental cohesive energies for the parent diamond...
February 14, 2017: Physical Chemistry Chemical Physics: PCCP
Yifan Wang, Ian C Jenkins, James T McGinley, Talid Sinno, John C Crocker
Future optical materials promise to do for photonics what semiconductors did for electronics, but the challenge has long been in creating the structure they require-a regular, three-dimensional array of transparent microspheres arranged like the atoms in a diamond crystal. Here we demonstrate a simple approach for spontaneously growing double-diamond (or B32) crystals that contain a suitable diamond structure, using DNA to direct the self-assembly process. While diamond symmetry crystals have been grown from much smaller nanoparticles, none of those previous methods suffice for the larger particles needed for photonic applications, whose size must be comparable to the wavelength of visible light...
February 13, 2017: Nature Communications
Michael Lübtow, Ingo Helmers, Vladimir Stepanenko, Rodrigo Queiroz Albuquerque, Todd Benjamin Marder, Gustavo Fernandez
9,10-Bis(phenylethynyl)anthracenes (BPEAs) are an important class of dyes with various applications including chemiluminescent emitters, materials for photon upconversion and for optoelectronic devices. Some of these applications require control over the packing modes of the active molecules within the active layer, which can be effected by bottom-up self-assembly. Studies aimed at controllling the molecular organization of BPEAs have primarily focused on bulk or liquid crystal materials, while in-depth investigations of BPEA-based assemblies in solution remain elusive...
February 10, 2017: Chemistry: a European Journal
Janne-Mieke Meijer, Antara Pal, Samia Ouhajji, Henk N W Lekkerkerker, Albert P Philipse, Andrei V Petukhov
Self-organization in anisotropic colloidal suspensions leads to a fascinating range of crystal and liquid crystal phases induced by shape alone. Simulations predict the phase behaviour of a plethora of shapes while experimental realization often lags behind. Here, we present the experimental phase behaviour of superball particles with a shape in between that of a sphere and a cube. In particular, we observe the formation of a plastic crystal phase with translational order and orientational disorder, and the subsequent transformation into rhombohedral crystals...
February 10, 2017: Nature Communications
Bartolomeo Della Ventura, Marco Iannaccone, Riccardo Funari, Massimo Pica Ciamarra, Carlo Altucci, Rosanna Capparelli, Sante Roperto, Raffaele Velotta
BACKGROUND: Biosensor-based detection provides a rapid and low-cost alternative to conventional analytical methods for revealing the presence of the contaminants in water as well as solid matrices. Although important to be detected, small analytes (few hundreds of Daltons) are an issue in biosensing since the signal they induce in the transducer, and specifically in a Quartz-Crystal Microbalance, is undetectable. A pesticide like parathion (M = 292 Da) is a typical example of contaminant for which a signal amplification procedure is desirable...
2017: PloS One
Siqi Yan, Xiaolong Zhu, Lars Hagedorn Frandsen, Sanshui Xiao, N Asger Mortensen, Jianji Dong, Yunhong Ding
Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light-matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally demonstrate an energy-efficient graphene microheater with a tuning efficiency of 1.07 nmmW(-1) and power consumption per free spectral range of 3.99 mW. The rise and decay times (10-90%) are only 750 and 525 ns, which, to the best of our knowledge, are the fastest reported response times for microheaters in silicon photonics...
February 9, 2017: Nature Communications
Li Tao, Henry M Daghighian, Craig S Levin
We compare the performance of two detector materials, cadmium telluride (CdTe) and bismuth silicon oxide (BSO), for optical property modulation-based radiation detection method for positron emission tomography (PET), which is a potential new direction to dramatically improve the annihilation photon pair coincidence time resolution. We have shown that the induced current flow in the detector crystal resulting from ionizing radiation determines the strength of optical modulation signal. A larger resistivity is favorable for reducing the dark current (noise) in the detector crystal, and thus the higher resistivity BSO crystal has a lower (50% lower on average) noise level than CdTe...
January 2017: Journal of Medical Imaging
Fernando Galve, Antonio Mandarino, Matteo G A Paris, Claudia Benedetti, Roberta Zambrini
Practical implementations of quantum technology are limited by unavoidable effects of decoherence and dissipation. With achieved experimental control for individual atoms and photons, more complex platforms composed by several units can be assembled enabling distinctive forms of dissipation and decoherence, in independent heat baths or collectively into a common bath, with dramatic consequences for the preservation of quantum coherence. The cross-over between these two regimes has been widely attributed in the literature to the system units being farther apart than the bath's correlation length...
February 8, 2017: Scientific Reports
Mohamed Shaban, Ashour M Ahmed, Ehab Abdel-Rahman, Hany Hamdy
Gold/one-dimensional photonic crystal (Au/1D-PC) is fabricated and applied for sensitive sensing of glucose and different chemical molecules of various refractive indices. The Au layer thickness is optimized to produce surface plasmon resonance (SPR) at the right edge of the photonic band gap (PBG). As the Au deposition time increased to 60 sec, the PBG width is increased from 46 to 86 nm in correlation with the behavior of the SPR. The selectivity of the optimized Au/1D-PC sensor is tested upon the increase of the environmental refractive index of the detected molecules...
February 8, 2017: Scientific Reports
Travis M Shaffer, Edwin C Pratt, Jan Grimm
The characteristic blue glow of Cerenkov luminescence (CL) arises from the interaction between a charged particle travelling faster than the phase velocity of light and a dielectric medium, such as water or tissue. As CL emanates from a variety of sources, such as cosmic events, particle accelerators, nuclear reactors and clinical radionuclides, it has been used in applications such as particle detection, dosimetry, and medical imaging and therapy. The combination of CL and nanoparticles for biomedicine has improved diagnosis and therapy, especially in oncological research...
February 7, 2017: Nature Nanotechnology
Ji-Hun Kang, Sheng Wang, Zhiwen Shi, Wenyu Zhao, Eli Yablonovitch, Feng Wang
Two-dimensional surface polaritons (2DSPs), such as graphene plasmons, exhibit various unusual properties, including electrical tunability and strong spatial confinement with high Q-factor, which can enable tunable photonic devices for deep subwavelength light manipulations. Reflection of plasmons at the graphene's edge plays a critical role in the manipulation of 2DSP and enables their direct visualization in near-field infrared microscopy. However, a quantitative understanding of the edge-reflections, including reflection phases and diffraction effects, has remained elusive...
February 8, 2017: Nano Letters
Min-Soo Hwang, Ha-Reem Kim, Kyoung-Ho Kim, Kwang-Yong Jeong, Jin-Sung Park, Jae-Hyuck Choi, Ju-Hyung Kang, Jung Min Lee, Won Il Park, Jung-Hwan Song, Min-Kyo Seo, Hong-Gyu Park
Unique features of graphene have motivated the development of graphene-integrated photonic devices. In particular, the electrical tunability of graphene loss enables high-speed modulation of light and tuning of cavity resonances in graphene-integrated waveguides and cavities. However, efficient control of light emission such as lasing, using graphene, remains a challenge. In this work, we demonstrate on/off switching of single- and double-cavity photonic crystal lasers by electrical gating of a monolayer graphene sheet on top of photonic crystal cavities...
February 6, 2017: Nano Letters
Dennis Go, Dirk Rommel, Lisa Chen, Feng Shi, Joris Sprakel, Alexander J C Kuehne
Soft amphoteric microgel systems exhibit a rich phase behavior. Crystalline phases of these material systems are of interest because they exhibit photonic stop-gaps, giving rise to iridescent color. Such microgel systems are promising for applications in soft, switchable and programmable photonic filters and devices. We here report a composite microgel system constisting of a hard and fluorescently labeled core and a soft, amphoteric microgel shell. At pH above the isoelectric point (IEP), these colloids easily crystallize into three-dimensional colloidal assemblies...
February 6, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Md Saiful Islam, Jakeya Sultana, Javid Atai, Derek Abbott, Sohel Rana, Mohammad Rakibul Islam
In this paper, we present the design and analysis of a novel hybrid porous core octagonal lattice photonic crystal fiber for terahertz (THz) wave guidance. The numerical analysis is performed using a full-vector finite element method (FEM) that shows that 80% of bulk absorption material loss of cyclic olefin copolymer (COC), commercially known as TOPAS can be reduced at a core diameter of 350 μm. The obtained effective material loss (EML) is as low as 0.04  cm<sup>-1</sup> at an operating frequency of 1 THz with a core porosity of 81%...
February 1, 2017: Applied Optics
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