This tutorial provides an intuitive and concrete description of the phenomena of electromagnetic nonreciprocity that will be useful for readers with engineering or physics backgrounds. The notion of ...time reversal and its different definitions are discussed with special emphasis on its relationship with the reciprocity concept. Starting from the Onsager reciprocal relations that are generally applicable to many physical processes, we present the derivation of the Lorentz theorem and discuss other implications of reciprocity for electromagnetic systems. Next, we identify all possible routes toward engineering nonreciprocal devices and analyze three of them in detail, based on external bias and on nonlinear and time-variant systems. The principles of the operation of different nonreciprocal devices are explained. We address the similarity and fundamental difference between nonreciprocal effects and asymmetric transmission in reciprocal systems. In addition to the tutorial description of the topic, this article also contains the original findings. In particular, the general classification of reciprocal and nonreciprocal phenomena in linear bianisotropic media based on the space- and time-reversal symmetries is presented. This classification serves as a powerful tool for drawing analogies between seemingly distinct effects having the same physical origin and can be used for predicting novel electromagnetic phenomena. Furthermore, electromagnetic reciprocity theorem for time-varying systems is derived, and its applicability is discussed.
An artificial retina system shows a promising potential to achieve fast response, low power consumption, and high integration density for vision sensing systems. Optoelectronic sensors, which can ...emulate the neurobiological functionalities of retinal neurons, are crucial in the artificial retina systems. Here, we propose a WSe
phototransistor with asymmetrical van der Waals (vdWs) stacking that can be used as an optoelectronic sensor in artificial retina systems. Through the utilization of the gate-tunable self-powered bidirectional photoresponse of this phototransistor, the neurobiological functionalities of both bipolar cells and cone cells, as well as the hierarchical connectivity between these two types of retinal neurons, are successfully mimicked by a single device. This self-powered bidirectional photoresponse is attributed to the asymmetrical vdWs stacking structure, which enables the transition from an n-p to p
-p homojunction in the WSe
channel under different polarities of gate bias. Moreover, the detectivity and ON/OFF ratio of this phototransistor reach as high as 1.8 × 10
Jones and 5.3 × 10
, respectively, and a rise/fall time <80 μs is achieved, as well, which reveals good photodetection performance. The proof of this device provides a pathway for the future development of neuromorphic vision devices and systems.
Nonlinear optics in daily life Garmire, Elsa
Optics express,
2013-Dec-16, 2013-12-16, 20131216, Volume:
21, Issue:
25
Journal Article
Peer reviewed
Open access
An overview is presented of the impact of NLO on today's daily life. While NLO researchers have promised many applications, only a few have changed our lives so far. This paper categorizes ...applications of NLO into three areas: improving lasers, interaction with materials, and information technology. NLO provides: coherent light of different wavelengths; multi-photon absorption for plasma-materials interaction; advanced spectroscopy and materials analysis; and applications to communications and sensors. Applications in information processing and storage seem less mature.
Femtosecond laser micromachining of transparent material is a powerful and versatile technology. In fact, it can be applied to several materials. It is a maskless technology that allows rapid device ...prototyping, has intrinsic three-dimensional capabilities and can produce both photonic and microfluidic devices. For these reasons it is ideally suited for the fabrication of complex microsystems with unprecedented functionalities. The book is mainly focused on micromachining of transparent materials which, due to the nonlinear absorption mechanism of ultrashort pulses, allows unique three-dimensional capabilities and can be exploited for the fabrication of complex microsystems with unprecedented functionalities.This book presents an overview of the state of the art of this rapidly emerging topic with contributions from leading experts in the field, ranging from principles of nonlinear material modification to fabrication techniques and applications to photonics and optofluidics. Roberto Osellame is a Research Associate at the Institute of Photonics and Nanotechnology (IFN), Milan, Italy, of the National Research Council (CNR). From 2001 he is also a Contract Professor of Experimental Physics at the Politecnico di Milano. His research interests include integrated all-optical devices on nonlinear crystals, femtosecond laser micromachining of transparent material, fabrication and characterization of photonic and optofluidic devices and biophotonic applications. He is author of more than 60 scientific papers in premier peer-reviewed journals and received several invitations to major international conferences. He is inventor of two licensed patents in the field of photonics. He is in the technical program committees of the conferences CLEO Europe and Photonics West. He is currently the project coordinator of the 7th Framework Program EU project 'microFLUID' (2008-2011). Giulio Cerullo is Associate Professor of Physics at Politecnico di Milano. His current scientific interests concern generation of few-optical-cycle pulses, ultrafast spectroscopy with time resolution down to a few femtoseconds, and micro/nanostructuring by ultrashort pulses. He is the author of about 200 papers in international journals and has given over 40 invited presentations at international conferences. He is in the technical program committees of the conferences CLEO Europe, CLEO U.S.A., Photonics Europe and Ultrafast Phenomena. He is Topical Editor of the journal Optics Letters for the topic Ultrafast Optical Phenomena. He coordinates the European project HIBISCUS (Hybrid Integrated Bio-Sensors Created by Ultrafast Laser Sources). Roberta Ramponi is Full Professor of Physics at the Politecnico di Milano, and chair of the bachelor and master-of-science degrees in Physics Engineering. She has a long-standing cooperation with the CNR Institute of Photonics and Nanotechnology as associate researcher. Her research activity includes integrated and nonlinear optics, the development of novel fabrication and characterization techniques for optical waveguides, and photonic devices for applications to telecommunications and to biomedical and environmental sensing. She is co-author of over 130 international publications. She was the President of the European Optical Society (EOS) in 2006-2008, now being the Past-President.
A self-contained introduction to the main aspects of high-power laser-matter interaction in the intensity range 10^10-10^22 W/cm^2 from plasma formation to highly relativistic interactions of the ...laser field with matter is presented. It is intended as a guide for scientists and students who have just discovered the field as a new and attractive area of research, and for scientists who have worked in another field and want to join now the subject of laser plasmas. In the first chapter the plasma dynamics is described phenomenologically by a two fluid model and similarity relations from dimensional analysis. Chapter 2 is devoted to plasma optics and collisional absorption in the dielectric and ballistic model. Linear resonance absorption at the plasma frequency and its mild nonlinearities as well as the self-quenching of high amplitude electron plasma waves by wave breaking are discussed in Chapter 3. With increasing laser intensity the plasma dynamics is dominated by radiation pressure, at resonance producing all kinds of parametric instabilities and out of resonance leading to density steps, self-focusing and filamentation, described in Chapters 4 and 5.A self-contained treatment of field ionization of atoms and related phenomena are found in Chapter 6. The extension of laser interaction to the relativistic electron acceleration as well as the physics of collisionless absorption are the subject of Chapter 7. Throughout the book the main emphasis is on the various basic phenomena and on their underlying physics.
Controlling electromagnetic waves and information simultaneously by information metasurfaces is of central importance in modern society. Intelligent metasurfaces are smart platforms to manipulate the ...wave–information–matter interactions without manual intervention by synergizing engineered ultrathin structures with active devices and algorithms, which evolve from the passive composite materials for tailoring wave–matter interactions that cannot be achieved in nature. Here, we review the recent progress of intelligent metasurfaces in wave–information–matter controls by providing the historical background and underlying physical mechanisms. Then we explore the application of intelligent metasurfaces in developing novel wireless communication architectures, with particular emphasis on metasurface-modulated backscatter wireless communications. We also explore the wave-based computing by using the intelligent metasurfaces, focusing on the emerging research direction in intelligent sensing. Finally, we comment on the challenges and highlight the potential routes for the further developments of the intelligent metasurfaces for controls, communications and computing.
Reduced graphene oxides (RG-Os) have attracted considerable interest, given their potential applications in electronic and optoelectronic devices and circuits. However, very little is known regarding ...the chemically induced reduction method of graphene oxide (G-O) in both solution and gas phases, with the exception of the hydrazine-reducing agent, even though it is essential to use the vapour phase for the patterning of hydrophilic G-Os on prepatterned substrates and in situ reduction to hydrophobic RG-Os. In this paper, we report a novel reducing agent system (hydriodic acid with acetic acid (HI-AcOH)) that allows for an efficient, one-pot reduction of a solution-phased RG-O powder and vapour-phased RG-O (VRG-O) paper and thin film. The reducing agent system provided highly qualified RG-Os by mass production, resulting in highly conducting RG-O(HI-AcOH). Moreover, VRG-O(HI-AcOH) paper and thin films were prepared at low temperatures (40 °C) and were found to be applicable to flexible devices. This one-pot method is expected to advance research on highly conducting graphene platelets.
Optically pumped magnetometers (OPMs) operating in the spin-exchange relaxation-free regime are emerging as alternative sensors to superconducting quantum interference devices (SQUIDs) for ...magnetoencephalography (MEG). As the number of OPMs in a single imaging system increases to rival SQUID MEG systems, cross-talk between nearby sensors limits the measurement accuracy. We experimentally demonstrate a coil geometry, which generates an order of magnitude less cross-talk (less than 0.5%) than a Helmholtz coil (8%). The new coil design is simple and compact, requiring two coaxial coil pairs that add 1 mm to the 6 mm radius and is driven by a single current driver. The new design maintains a magnetic field homogeneity over the volume of the magnetometer of more than 94%, which is sufficient for the zero-field OPM to operate in a 200 nT ambient field environment. Our result increases the feasibility of high-spatial resolution OPM-based bio-magnetic imaging technology due to the reduction of cross-talk at high sensor density.
All‐optical modulators, where one light modulates the parameters of another light (intensity, phase, frequency, etc.) without external electronic control, have drawn extraordinary attention in ...all‐optical information processing. In this contribution, by taking advantage of the two‐pass structure of Michelson interferometer and the strong photothermal conversion efficiency of MXene nanomaterials, an all‐optical modulator is demonstrated with a modulation depth of >27 dB, a free spectrum range of 16.8 nm and a pump‐induced phase shift slope of 0.043 π mW−1. Moreover, the all‐optical modulator is successfully employed to switch on/off the intensity of the signal light and load information from one channel to another with comparable response time and baudrate. It is believed that the MXene‐based all‐optical modulator will open a door to practical applications of 2D materials‐based all‐optical devices in all‐optical signal processing.
By taking advantage of the two‐pass structure of Michelson interferometer and the strong photothermal conversion efficiency of MXene nanomaterials, a novel all‐optical modulator is presented. This modulator can be employed to achieve phase modulation with large free spectrum range and high modulation depth, intensity modulation with fast response time, and information loading with arbitrary programmable input codes.
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