Showing papers in "Journal of Optics in 2017"
University of Queensland1, University of the Witwatersrand2, University of Bristol3, University of East Anglia4, University of Arizona5, University of Münster6, Max Planck Society7, University of Ottawa8, Istituto Nazionale di Fisica Nucleare9, University of Glasgow10, Innsbruck Medical University11, State University of New York System12, The Institute of Optics13, Polytechnic University of Catalonia14, University of Victoria15, University of Southern California16, University of Oregon17, Purdue University18
TL;DR: In this paper, the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face, as well as the exciting prospects for the future that are yet to be realized.
Abstract: Structured light refers to the generation and application of custom light fields. As the tools and technology to create and detect structured light have evolved, steadily the applications have begun to emerge. This roadmap touches on the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face. Collectively the roadmap outlines the venerable nature of structured light research and the exciting prospects for the future that are yet to be realized.
639 citations
TL;DR: In this paper, the spin and orbital dynamics of single defects are driven by the motion of a mechanical oscillator, and prospective applications for this device, including long range, phonon-mediated spin-spin interactions, and phonon cooling in the quantum regime.
Abstract: There has been rapidly growing interest in hybrid quantum devices involving a solid-state spin and a macroscopic mechanical oscillator. Such hybrid devices create exciting opportunities to mediate interactions between disparate qubits and to explore the quantum regime of macroscopic mechanical objects. In particular, a system consisting of the nitrogen-vacancy defect center in diamond coupled to a high quality factor mechanical oscillator is an appealing candidate for such a hybrid quantum device, as it utilizes the highly coherent and versatile spin properties of the defect center. In this paper, we will review recent experimental progress on diamond-based hybrid quantum devices in which the spin and orbital dynamics of single defects are driven by the motion of a mechanical oscillator. In addition, we discuss prospective applications for this device, including long range, phonon-mediated spin-spin interactions, and phonon cooling in the quantum regime. We conclude the review by evaluating the experimental limitations of current devices and identifying alternative device architectures that may reach the strong coupling regime.
175 citations
TL;DR: Mice treated with transcranial photobiomodulation for treating traumatic brain injury in mice had improved memory and learning, increased neuroprogenitor cells in the dentate gyrus and subventricular zone, increased BDNF and more synaptogenesis in the cortex, suggesting that the applications of tLLLT are much broader than at first conceived.
Abstract: Transcranial photobiomodulation (PBM) also known as low level laser therapy (tLLLT) relies on the use of red/NIR light to stimulate, preserve and regenerate cells and tissues. The mechanism of action involves photon absorption in the mitochondria (cytochrome c oxidase), and ion channels in cells leading to activation of signaling pathways, up-regulation of transcription factors, and increased expression of protective genes. We have studied PBM for treating traumatic brain injury (TBI) in mice using a NIR laser spot delivered to the head. Mice had improved memory and learning, increased neuroprogenitor cells in the dentate gyrus and subventricular zone, increased BDNF and more synaptogenesis in the cortex. These highly beneficial effects on the brain suggest that the applications of tLLLT are much broader than at first conceived. Other groups have studied stroke (animal models and clinical trials), Alzheimer's disease, Parkinson's disease, depression, and cognitive enhancement in healthy subjects.
135 citations
TL;DR: In this article, the authors present an overview of the current state-of-the-art mid-IR sources, in particular thermal emitters, which have long been utilized, and the relatively new quantumand interband-cascade lasers, as well as the applications served by these sources.
Abstract: The mid-infrared (mid-IR) is a wavelength range with a variety of technologically vital applications in molecular sensing, security and defense, energy conservation, and potentially in free-space communication. The recent development and rapid commercialization of new coherent mid-infrared sources have spurred significant interest in the development of mid-infrared optical systems for the above applications. However, optical systems designers still do not have the extensive optical infrastructure available to them that exists at shorter wavelengths (for instance, in the visible and near-IR/telecom wavelengths). Even in the field of optoelectronic sources, which has largely driven the growing interest in the mid-infrared, the inherent limitations of state-of-the-art sources and the gaps in spectral coverage offer opportunities for the development of new classes of lasers, light emitting diodes and emitters for a range of potential applications. In this topical review, we will first present an overview of the current state-of-the-art mid-IR sources, in particular thermal emitters, which have long been utilized, and the relatively new quantumand interband-cascade lasers, as well as the applications served by these sources. Subsequently, we will discuss potential midinfrared applications and wavelength ranges which are poorly served by the current stable of mid-IR sources, with an emphasis on understanding the fundamental limitations of the current source technology. The bulk of the manuscript will then explore both past and recent developments in midinfrared source technology, including narrow bandgap quantum well lasers, type-I and type-II quantum dot materials, type-II superlattices, highly mismatched alloys, lead-salts and transitionmetal-doped II-VI materials. We will discuss both the advantages and limitations of each of the above material systems, as well as the potential new applications which they might serve. All in all, this topical review does not aim to provide a survey of the current state of the art for mid-IR sources, but instead looks primarily to provide a picture of potential next-generation optical and optoelectronic materials systems for mid-IR light generation.
107 citations
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TL;DR: In this article, the authors address the technology of Raman fiber laser, specifically focused on the most recent developments, and discuss several applications of high-power fiber laser in laser pumping, frequency conversion, optical communications and biology.
Abstract: High-power fiber lasers have seen tremendous development in the last decade, with output powers exceeding multiple kilowatts from a single fiber. Ytterbium has been at the forefront as the primary rare-earth-doped gain medium owing to its inherent material advantages. However, for this reason, the lasers are largely confined to the narrow emission wavelength region of ytterbium. Power scaling at other wavelength regions has lagged significantly, and a large number of applications rely upon the diversity of emission wavelengths. Currently, Raman fiber lasers are the only known wavelength agile, scalable, high-power fiber laser technology that can span the wavelength spectrum. In this review, we address the technology of Raman fiber lasers, specifically focused on the most recent developments. We will also discuss several applications of Raman fiber lasers in laser pumping, frequency conversion, optical communications and biology.
107 citations
TL;DR: In this paper, a review of optical and acoustic metamaterials in the past 15 years is presented, which may lead to exciting applications in communications, sensing, and imaging.
Abstract: Metamaterials are artificially engineered materials that exhibit novel properties beyond natural materials. By carefully designing the subwavelength unit cell structures, unique effective properties that do not exist in nature can be attained. Our metamaterial research aims to develop new subwavelength structures with unique physics and experimentally demonstrate unprecedented properties. Here we review our research efforts in optical and acoustic metamaterials in the past 15 years which may lead to exciting applications in communications, sensing and imaging.
100 citations
99 citations
TL;DR: Details of the physical principle and theory of quantum memory based specifically on EIT are provided and important milestones from the first experimental demonstration to current applications in quantum information systems are reviewed.
Abstract: Electromagnetically induced transparency (EIT) is a promising approach to implement quantum memory in quantum communication and quantum computing applications. In this paper, following a brief overview of the main approaches to quantum memory, we provide details of the physical principle and theory of quantum memory based specifically on EIT. We discuss the key technologies for implementing quantum memory based on EIT and review important milestones, from the first experimental demonstration to current applications in quantum information systems.
89 citations
TL;DR: In this paper, nonlinear optical conversion can be used to not only diversify the output wavelength of these sources, but also uniquely engineer the wavefront and spatial properties of the laser output.
Abstract: The unique properties of optical vortex beams, in particular their spiral wavefront, have resulted in the emergence of a wide range of unique applications for this type of laser output. These applications include optical tweezing, free space optical communications, microfabrication, environmental optics, and astrophysics. However, much like the laser in its infancy, the adaptation of this type of laser output requires a diversity of wavelengths. We report on recent progress on development of optical vortex laser sources and in particular, focus on their wavelength extension, where nonlinear optical processes have been used to generate vortex laser beams with wavelengths which span the ultraviolet to infrared. We show that nonlinear optical conversion can be used to not only diversify the output wavelength of these sources, but can be used to uniquely engineer the wavefront and spatial properties of the laser output.
88 citations
87 citations
TL;DR: In this paper, the potentialities and the achievements of the use of non-classical photon number correlations in twin beams (TWB) states for many applications, ranging from imaging to metrology.
Abstract: In this review we present the potentialities and the achievements of the use of non-classical photon number correlations in twin beams (TWB) states for many applications, ranging from imaging to metrology. Photon number correlations in the quantum regime are easy to be produced and are rather robust against unavoidable experimental losses, and noise in some cases, if compared to the entanglement, where loosing one photon can completely compromise the state and its exploitable advantage. Here, we will focus on quantum enhanced protocols in which only phase-insensitive intensity measurements (photon number counting) are performed, which allow probing transmission/absorption properties of a system, leading for example to innovative target detection schemes in a strong background. In this framework, one of the advantages is that the sources experimentally available emit a wide number of pairwise correlated modes, which can be intercepted and exploited separately, for example by many pixels of a camera, providing a parallelism, essential in several applications, like wide field sub-shot-noise imaging and quantum enhanced ghost imaging. Finally, non-classical correlation enables new possibilities in quantum radiometry, e.g. the possibility of absolute calibration of a spatial resolving detector from the on-off- single photon regime to the linear regime, in the same setup.
TL;DR: In this paper, a single-shot incoherent digital holography in which a singlepath in-line configuration and phase-shifting interferometry are adopted is proposed.
Abstract: We propose single-shot incoherent digital holography in which a single-path in-line configuration and phase-shifting interferometry are adopted Space-division multiplexing and polarization states of the waves are utilized to implement parallel phase-shifting holography A single-path setup in parallel phase-shifting is constructed to capture an incoherent hologram easily with a compact system An instantaneous and three-dimensional (3D) object image is obtained without undesired diffraction waves using parallel phase-shifting The validity of the proposed technique is experimentally demonstrated for both transparent and reflective objects
TL;DR: In this paper, the authors describe the principle of each of these photostimulation techniques and review the use of these approaches in optogenetics experiments by presenting their advantages and drawbacks.
Abstract: An important technological revolution is underway in the field of neuroscience as we begin the 21st century. The combination of optical methods with genetically encoded photosensitive tools (optogenetics) offers the opportunity to quickly modulate and monitor a large number of neuronal events and the ability to recreate the physiological, spatial, and temporal patterns of brain activity. The use of light instead of electrical stimulation is less invasive, and permits superior spatial and temporal specificity and flexibility. This ongoing revolution has motivated the development of new optical methods for light stimulation. They can be grouped in two main categories: scanning and parallel photostimulation techniques, each with its advantages and limitations. In scanning approaches, a small light spot is displaced in targeted regions of interest (ROIs), using galvanometric mirrors or acousto-optic deflectors, whereas in parallel approaches, the light beam can be spatially shaped to simultaneously cover all ROIs by modulating either the light intensity or the phase of the illumination beam. With amplitude modulation, light patterns are created by selectively blocking light rays that illuminate regions of no interest, while with phase modulation, the wavefront of the light beam is locally modified so that light rays are directed onto the target, thus allowing for higher intensity efficiency. In this review, we will describe the principle of each of these photostimulation techniques and review the use of these approaches in optogenetics experiments by presenting their advantages and drawbacks. Finally, we will review the challenges that need to be faced when photostimulation methods are combined with two-photon imaging approaches to reach an all-optical brain control through optogenetics and functional reporters (Ca and voltage indicators). Journal of Optics J. Opt. 19 (2017) 113001 (27pp) https://doi.org/10.1088/2040-8986/aa8299 Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. 2040-8978/17/113001+27$33.00 © 2017 IOP Publishing Ltd Printed in the UK 1
TL;DR: In this paper, the state of the art in the field of nonlinear silicon photonic circuits is discussed, starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described.
Abstract: Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms of the dominating electronics industry. After twenty years of impetuous development, silicon photonics is entering the market with low cost, high performance and mass manufacturable optical devices. Up to now, most of the silicon photonic devices are based on linear optical effects, despite the many phenomenologies associated to nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross section of the high index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review article to make the point of the state of the art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described: from frequency generation, frequency conversion, frequency comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, up to comb spectroscopy. Emerging quantum photonics applications, as entangled photon sources, heralded single photon sources and integrated quantum photonic circuits, are also addressed at the end of the review.
University of Pavia1, Leonardo2, University of Padua3, Tufts University4, Royal Institute of Technology5, University of California, Los Angeles6, Duke University7, University of Twente8, University of California, Santa Cruz9, National Research Council10, Dresden University of Technology11, King Abdullah University of Science and Technology12, Technical University of Denmark13, Chinese Academy of Sciences14, University of Surrey15, Nanyang Technological University16, National Taiwan University17, Cornell University18, University of Toronto19
TL;DR: Optofluidics, nominally the research area where optics and fluidics merge, is a relatively new research field and it is only in the last decade that there has been a large increase in the number of...
Abstract: Optofluidics, nominally the research area where optics and fluidics merge, is a relatively new research field and it is only in the last decade that there has been a large increase in the number of ...
University of Aveiro1, Centro de Investigaciones en Optica2, University of Adelaide3, Carlos III Health Institute4, University of Cantabria5, Beijing University of Technology6, Hong Kong Polytechnic University7, Seoul National University8, Max Planck Society9, Zhejiang University10, Boston University11, United States Army Research Laboratory12, Northeastern University13, University of Exeter14, Harvard University15
TL;DR: This roadmap on optical sensors addresses different technologies and application areas of the field, including laser-based and frequency comb-based sensors, and the area of optical fiber sensors, encompassing both conventional, specialty and photonic crystal fibers.
Abstract: Sensors are devices or systems able to detect, measure and convert magnitudes from any domain to an electrical one. Using light as a probe for optical sensing is one of the most efficient approaches for this purpose. The history of optical sensing using some methods based on absorbance, emissive and florescence properties date back to the 16th century. The field of optical sensors evolved during the following centuries, but it did not achieve maturity until the demonstration of the first laser in 1960. The unique properties of laser light become particularly important in the case of laser-based sensors, whose operation is entirely based upon the direct detection of laser light itself, without relying on any additional mediating device. However, compared with freely propagating light beams, artificially engineered optical fields are in increasing demand for probing samples with very small sizes and/or weak light-matter interaction. Optical fiber sensors constitute a subarea of optical sensors in which fiber technologies are employed. Different types of specialty and photonic crystal fibers provide improved performance and novel sensing concepts. Actually, structurization with wavelength or subwavelength feature size appears as the most efficient way to enhance sensor sensitivity and its detection limit. This leads to the area of micro- and nano-engineered optical sensors. It is expected that the combination of better fabrication techniques and new physical effects may open new and fascinating opportunities in this area. This roadmap on optical sensors addresses different technologies and application areas of the field. Fourteen contributions authored by experts from both industry and academia provide insights into the current state-of-the-art and the challenges faced by researchers currently. Two sections of this paper provide an overview of laser-based and frequency comb-based sensors. Three sections address the area of optical fiber sensors, encompassing both conventional, specialty and photonic crystal fibers. Several other sections are dedicated to micro- and nano-engineered sensors, including whispering-gallery mode and plasmonic sensors. The uses of optical sensors in chemical, biological and biomedical areas are described in other sections. Different approaches required to satisfy applications at visible, infrared and THz spectral regions are also discussed. Advances in science and technology required to meet challenges faced in each of these areas are addressed, together with suggestions on how the field could evolve in the near future.
TL;DR: Theoretical and numerical aspects of the interaction of electrons with nanostructures and metamaterials are discussed in this paper, with the aim to understand mechanisms of radiation in interaction of electron with even more sophisticated structures.
Abstract: Investigating the interaction of electron beams with materials and light has been a field of research since more than a century. The field was advanced theoretically by the raise of quantum mechanics and technically by the introduction of electron microscopes and accelerators. It is possible nowadays to uncover a multitude of information from electron-induced excitations in matter by means of advanced techniques like holography, tomography, and most recently photon-induced near-field electron microscopy. The question is whether the interaction can be controlled in an even more efficient way in order to unravel important questions like modal decomposition of the electron-induced polarization, by performing experiments with better spatial, temporal, and energy resolutions. This review discusses recent advances in controlling the electron and light interactions at the nanoscale. Theoretical and numerical aspects of the interaction of electrons with nanostructures and metamaterials will be discussed, with the aim to understand mechanisms of radiation in interaction of electrons with even more sophisticated structures.
TL;DR: In this article, the authors numerically show that strong anisotropic perfect absorption can be realized in a nanostructured monolayer black phosphorus with the excitation of plasmonic resonances.
Abstract: Black phosphorus exhibits extreme anisotropic properties due to its special lattice structure. In this paper, we numerically show that strong anisotropic perfect absorption can be realized in a nanostructured monolayer black phosphorus with the excitation of plasmonic resonances. Under normal incidences, the structure shows a 99.56% absorption for one polarization at the resonance wavelength while only 9.48% absorption for the other polarization at the same wavelength. The anisotropic responses are purely attributed to the intrinsic material anisotropy of black phosphorus which is different from conventional metallic or graphene plasmonic absorbers. The wavelength of peak absorption is tunable by changing the electron concentration in black phosphorus. As an example of application, we proposed a new design of tunable reflective polarizer based on black phosphorus and a polarization extinction ratio around 23 dB can be achieved.
TL;DR: In this article, the authors proposed new designs of ultrathin nonlinear metasurfaces composed of patterned graphene micro-ribbons to significantly enhance third harmonic generation (THG) at far-infrared and terahertz (THz) frequencies.
Abstract: The nonlinear responses of different materials provide useful mechanisms for optical switching, low noise amplification, and harmonic frequency generation. However, the nonlinear processes usually have an extremely weak nature and require high input power to be excited. To alleviate this severe limitation, we propose new designs of ultrathin nonlinear metasurfaces composed of patterned graphene micro-ribbons to significantly enhance third harmonic generation (THG) at far-infrared and terahertz (THz) frequencies. The incident wave is tightly confined and significantly boosted along the surface of graphene in these configurations due to the excitation of highly localized plasmons. The bandwidth of the resonant response becomes narrower due to the introduction of a metallic substrate below the graphene micro-ribbons, which leads to zero transmission and standing waves inside the intermediate dielectric spacer layer. The enhancement of the incident field, combined with the large nonlinear conductivity of graphene, can dramatically increase the THG conversion efficiency by several orders of magnitude. In addition, the resonant frequency of the metasurface can be adjusted by dynamically tuning the Fermi energy of graphene via electrical or chemical doping. As a result, the THG wave can be optimized and tuned to be emitted at different frequencies without the need to change the nonlinear metasurface geometry. The proposed nonlinear metasurfaces provide a new way to realize compact and efficient nonlinear sources at the far-infrared and THz frequency ranges, as well as new frequency generation and wave mixing devices which are expected to be useful for nonlinear THz spectroscopy and noninvasive THz imaging applications.
TL;DR: In this article, a self-contained tutorial on light beam multiplexing is provided, where readers are guided step-by-step in the process of light beam shaping and multiple-xing.
Abstract: The on-demand tailoring of light's spatial shape is of great relevance in a wide variety of research areas. Computer-controlled devices, such as spatial light modulators (SLMs) or digital micromirror devices, offer a very accurate, flexible and fast holographic means to this end. Remarkably, digital holography affords the simultaneous generation of multiple beams (multiplexing), a tool with numerous applications in many fields. Here, we provide a self-contained tutorial on light beam multiplexing. Through the use of several examples, the readers will be guided step by step in the process of light beam shaping and multiplexing. Additionally, we provide a quantitative analysis on the multiplexing capabilities of SLMs to assess the maximum number of beams that can be multiplexed on a single SLM, showing approximately 200 modes on a single hologram.
TL;DR: In this paper, the authors reported ghost imaging of a single nonreproducible temporal signal with kHz resolution by using pseudo-thermal speckle light patterns and a single detector array with a million of pixels working without any temporal resolution.
Abstract: We report ghost imaging of a single non-reproducible temporal signal with kHz resolution by using pseudo-thermal speckle light patterns and a single detector array with a million of pixels working without any temporal resolution. A set of speckle patterns is generated deterministically at a sampling rate of tens kHz, multiplied by the temporal signal and time integrated in a single shot by the camera. The temporal information is retrieved by computing the spatial intensity correlations between this time integrated image and each speckle pattern of the set.
TL;DR: In this article, an expression for the interference pattern that is valid in both the low and the high-gain regimes of parametric down-conversion was obtained, where the coherence of the light emitted by the two coherently pumped nonlinear crystals was controlled.
Abstract: Induced coherence in parametric down-conversion between two coherently pumped nonlinear crystals that share a common idler mode can be used as an imaging technique. Based on the interference between the two signal modes of the crystals, an image can be reconstructed. By obtaining an expression for the interference pattern that is valid in both the low- and the high-gain regimes of parametric down-conversion, we show how the coherence of the light emitted by the two crystals can be controlled. With our comprehensive analysis we provide deeper insight into recent discussions about the application of induced coherence to imaging in different regimes. Moreover, we propose a scheme for optimizing the visibility of the interference pattern so that it directly corresponds to the degree of coherence of the light generated in the two crystals. We find that this scheme leads in the high-gain regime to a visibility arbitrarily close to unity.
TL;DR: In this article, a photonic crystal fiber with hollow core filled with toluene is considered as a new system for coherent supercontinuum generation, and the dispersion characteristics are studied for various geometrical parameters of photonic fiber fibres.
Abstract: A photonic crystal fibre with hollow core filled with toluene is considered as a new system for coherent supercontinuum generation. The dispersion characteristics are studied for various geometrical parameters of photonic crystal fibres. Two structures with lattice constant 2 μm, filling factors d/Λ 0.3 and 0.35 and toluene core of diameters of 3.34 and 3.23 μm have flat dispersion in the near infrared range. The structure with d/Λ = 0.3 has all-normal dispersion characteristics in whole near-infrared wavelength range, while the second structure (d/Λ = 0.35) has anomalous dispersion for wavelengths longer than 1.5 μm. Although confinement losses in the considered structures are as high as 0.4 dB cm−1, we show that the generation of coherent supercontinuum in the range 1.0–1.7 μm with the pulse energy conversion of 16% is feasible in 4 cm long fibre samples with standard fibre femtosecond lasers.
TL;DR: In this article, a monolithically integrated high repetition rate (50 MHz) all-fiber femtosecond laser based on a soliton self-frequency shift providing 9 nJ, 75 fs pulses at 1650 nm.
Abstract: The spectral window lying between 1.6 and 1.7 μm is interesting for in-depth multiphoton microscopy of intact tissues due to reduced scattering and absorption in this wavelength range. However, wide adoption of this excitation range will rely on the availability of robust and cost-effective high peak power pulsed lasers operating at these wavelengths. In this communication, we report on a monolithically integrated high repetition rate (50 MHz) all-fiber femtosecond laser based on a soliton self-frequency shift providing 9 nJ, 75 fs pulses at 1650 nm. We illustrate its potential for biological microscopy by recording three-photon-excited fluorescence and third-harmonic generation images of mouse nervous tissue and developing Drosophila embryos labeled with a red fluorescent protein.
TL;DR: In this paper, a switchable controlled-Z gate is used to generate and manipulate two-qubit entangled states using a reconfigurable six-mode interferometer embedded in a silicon chip.
Abstract: Entanglement is a fundamental property of quantum mechanics, and is a primary resource in quantum information systems. Its manipulation remains a central challenge in the development of quantum technology. In this work, we demonstrate a device which can generate, manipulate, and analyse two-qubit entangled states, using miniature and mass-manufacturable silicon photonics. By combining four photon-pair sources with a reconfigurable six-mode interferometer, embedding a switchable entangling gate, we generate two-qubit entangled states, manipulate their entanglement, and analyse them, all in the same silicon chip. Using quantum state tomography, we show how our source can produce a range of entangled and separable states, and how our switchable controlled-Z gate operates on them, entangling them or making them separable depending on its configuration.