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Photonics, Volume 2, Issue 1 (March 2015), Pages 1-316

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Open AccessArticle Electromagnetically Induced Transparency in Symmetric Planar Metamaterial at THz Wavelengths
Photonics 2015, 2(1), 308-316; https://doi.org/10.3390/photonics2010308
Received: 18 February 2015 / Revised: 3 March 2015 / Accepted: 4 March 2015 / Published: 19 March 2015
Cited by 2 | Viewed by 2249 | PDF Full-text (322 KB) | HTML Full-text | XML Full-text
Abstract
We report the experimental observation and the evidence of the analogue of electromagnetically-induced transparency (EIT) in a symmetric planar metamaterial. This effect has been obtained in the THz range thanks to a destructive Fano-interference between the two first modes of an array of
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We report the experimental observation and the evidence of the analogue of electromagnetically-induced transparency (EIT) in a symmetric planar metamaterial. This effect has been obtained in the THz range thanks to a destructive Fano-interference between the two first modes of an array of multi-gap split ring resonators deposited on a silicon substrate. This structure is a planar thin film material with four-fold symmetry. Thanks to this property, a polarization-independent transmission has been achieved. The proposed metamaterial is well adapted to variety of slow-light applications in the infrared and optical range. Full article
(This article belongs to the Special Issue New Frontiers in Plasmonics and Metamaterials)
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Open AccessReview Recent Advancement on the Optical Properties of Two-Dimensional Molybdenum Disulfide (MoS2) Thin Films
Photonics 2015, 2(1), 288-307; https://doi.org/10.3390/photonics2010288
Received: 20 January 2015 / Revised: 3 March 2015 / Accepted: 4 March 2015 / Published: 16 March 2015
Cited by 55 | Viewed by 6564 | PDF Full-text (1254 KB) | HTML Full-text | XML Full-text
Abstract
The emergence of two-dimensional (2D) materials has led to tremendous interest in the study of graphene and a series of mono- and few-layered transition metal dichalcogenides (TMDCs). Among these TMDCs, the study of molybdenum disulfide (MoS2) has gained increasing attention due
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The emergence of two-dimensional (2D) materials has led to tremendous interest in the study of graphene and a series of mono- and few-layered transition metal dichalcogenides (TMDCs). Among these TMDCs, the study of molybdenum disulfide (MoS2) has gained increasing attention due to its promising optical, electronic, and optoelectronic properties. Of particular interest is the indirect to direct band-gap transition from bulk and few-layered structures to mono-layered MoS2, respectively. In this review, the study of these properties is summarized. The use of Raman and Photoluminescence (PL) spectroscopy of MoS2 has become a reliable technique for differentiating the number of molecular layers in 2D MoS2. Full article
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Open AccessArticle FMTPen: A Miniaturized Handheld Fluorescence Molecular Tomography Probe for Image-Guided Cancer Surgery
Photonics 2015, 2(1), 279-287; https://doi.org/10.3390/photonics2010279
Received: 19 February 2015 / Revised: 6 March 2015 / Accepted: 10 March 2015 / Published: 12 March 2015
Cited by 4 | Viewed by 1872 | PDF Full-text (713 KB) | HTML Full-text | XML Full-text
Abstract
We described a novel handheld device (termed FMTPen) for three-dimensional (3D) fluorescence molecular tomography (FMT). The FMTpen is characterized by its bendable structure and miniaturized size (10 mm in diameter) that can be potentially used as an intraoperative tool for the detection of
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We described a novel handheld device (termed FMTPen) for three-dimensional (3D) fluorescence molecular tomography (FMT). The FMTpen is characterized by its bendable structure and miniaturized size (10 mm in diameter) that can be potentially used as an intraoperative tool for the detection of tumor margins and for image-guided surgery. Several phantom experiments based on indocyanine green (ICG), an FDA approved near-infrared (NIR) fluorescent dye, were conducted to evaluate the imaging ability of this device. Two tumor-bearing mice were systematically injected with tumor-targeted NIR fluorescent probes (NIR-830-ATF68-IONP and NIR-830-ZHER2:343-IONP, respectively) and were then imaged to further demonstrate the ability of this FMT probe for imaging small animals. Full article
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Open AccessArticle Periodic Arrays of Film-Coupled Cubic Nanoantennas as Tunable Plasmonic Metasurfaces
Photonics 2015, 2(1), 270-278; https://doi.org/10.3390/photonics2010270
Received: 11 February 2015 / Accepted: 25 February 2015 / Published: 9 March 2015
Cited by 6 | Viewed by 2109 | PDF Full-text (1850 KB) | HTML Full-text | XML Full-text
Abstract
We show theoretically that a two-dimensional periodic array of metallic nanocubes in close proximity to a metallic film acts as a metasurface with tunable absorbance. The presence of a metallic film underneath the array of plasmonic nanocubes leads to an impedance matched plasmonic
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We show theoretically that a two-dimensional periodic array of metallic nanocubes in close proximity to a metallic film acts as a metasurface with tunable absorbance. The presence of a metallic film underneath the array of plasmonic nanocubes leads to an impedance matched plasmonic metasurface enhancing up to 4 times the absorbance of incident radiation, in the spectral region below 500 nm. The absorbance spectrum is weakly dependent on the angle of incidence and state of polarization of incident light a functionality which can find application in thermo-photovoltaics. Our calculations are based on a hybrid layer-multiple-scattering (hLMS) method based on a discrete-dipole approximation (DDA)/T-matrix point matching method. Full article
(This article belongs to the Special Issue New Frontiers in Plasmonics and Metamaterials)
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Open AccessArticle Towards Realistic Simulations of Macromolecules Irradiated under the Conditions of Coherent Diffraction Imaging with an X-ray Free-Electron Laser
Photonics 2015, 2(1), 256-269; https://doi.org/10.3390/photonics2010256
Received: 15 January 2015 / Revised: 10 February 2015 / Accepted: 12 February 2015 / Published: 4 March 2015
Cited by 11 | Viewed by 2050 | PDF Full-text (283 KB) | HTML Full-text | XML Full-text
Abstract
Biological samples are highly radiation sensitive. The rapid progress of their radiation damage prevents accurate structure determination of single macromolecular assemblies in standard diffraction experiments. However, computer simulations of the damage formation have shown that the radiation tolerance might be extended at very
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Biological samples are highly radiation sensitive. The rapid progress of their radiation damage prevents accurate structure determination of single macromolecular assemblies in standard diffraction experiments. However, computer simulations of the damage formation have shown that the radiation tolerance might be extended at very high intensities with ultrafast imaging such as is possible with the presently developed and operating x-ray free-electron lasers. Recent experiments with free-electron lasers on nanocrystals have demonstrated proof of the imaging principle at resolutions down to 1:6 Angstroms. However, there are still many physical and technical problems to be clarified on the way to imaging of single biomolecules at atomic resolution. In particular, theoretical simulations try to address an important question: How does the radiation damage progressing within an imaged single object limit the structural information about this object recorded in its diffraction image during a 3D imaging experiment? This information is crucial for adjusting pulse parameters during imaging so that high-resolution diffraction patterns can be obtained. Further, dynamics simulations should be used to verify the accuracy of the structure reconstruction performed from the experimental data. This is an important issue as the experimentally recorded diffraction signal is recorded from radiation-damaged samples. It also contains various kinds of background. In contrast, the currently used reconstruction algorithms assume perfectly coherent scattering patterns with shot noise only. In this review paper, we discuss the most important processes and effects relevant for imaging-related simulations that are not yet fully understood, or omitted in the irradiation description. We give estimates for their contribution to the overall radiation damage. In this way we can identify unsolved issues and challenges for simulations of x-ray irradiated single molecules relevant for imaging studies. They should be addressed during further development of these simulation tools. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Extreme Ultraviolet Stokesmeter for Pulsed Magneto-Optics
Photonics 2015, 2(1), 241-255; https://doi.org/10.3390/photonics2010241
Received: 9 January 2015 / Revised: 7 February 2015 / Accepted: 9 February 2015 / Published: 16 February 2015
Cited by 1 | Viewed by 1924 | PDF Full-text (2292 KB) | HTML Full-text | XML Full-text
Abstract
Several applications in material science and magnetic holography using extreme ultraviolet (EUV) radiation require the measurement of the degree and state of polarization. In this work, an instrument to measure simultaneously both parameters from EUV pulses is presented. The instrument determines the Stokes
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Several applications in material science and magnetic holography using extreme ultraviolet (EUV) radiation require the measurement of the degree and state of polarization. In this work, an instrument to measure simultaneously both parameters from EUV pulses is presented. The instrument determines the Stokes parameters after a reflection on an array of multilayer mirrors at the Brewster angle. The Stokesmeter was tested at Swiss Light Source at different EUV wavelengths. The experimental Stokes patterns of the source were compared with the simulated pattern. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Objectivisation In Simplified Quantum Brownian Motion Models
Photonics 2015, 2(1), 228-240; https://doi.org/10.3390/photonics2010228
Received: 14 January 2015 / Revised: 9 February 2015 / Accepted: 10 February 2015 / Published: 13 February 2015
Cited by 10 | Viewed by 1482 | PDF Full-text (2689 KB) | HTML Full-text | XML Full-text
Abstract
The birth of objective properties from the subjective quantum world has been one of the key questions in the quantum-to-classical transition. Based on recent results in the field, we study it in a quantum mechanical model of a boson-boson interaction—quantum Brownian motion. Using
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The birth of objective properties from the subjective quantum world has been one of the key questions in the quantum-to-classical transition. Based on recent results in the field, we study it in a quantum mechanical model of a boson-boson interaction—quantum Brownian motion. Using various simplifications, we prove a formation for thermal environments of, so called, spectrum broadcast structures, responsible for perceived objectivity. In the quantum measurement limit we prove that this structure is always formed, providing the characteristic timescales. Including self-Hamiltonians of the environment, we show the exponential scaling of the effect with the size of the environment. Finally, in the full model we numerically study the influence of squeezing in the initial state of the environment, showing broader regions of formation than for non-squeezed thermal states. Full article
(This article belongs to the Special Issue Quantum Optics and Quantum Information Processing)
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Open AccessArticle Squeezed Phonon Wave Packet Generation by Optical Manipulation of a Quantum Dot
Photonics 2015, 2(1), 214-227; https://doi.org/10.3390/photonics2010214
Received: 14 January 2015 / Revised: 6 February 2015 / Accepted: 7 February 2015 / Published: 12 February 2015
Cited by 3 | Viewed by 2938 | PDF Full-text (1193 KB) | HTML Full-text | XML Full-text
Abstract
In solid-state physics, the quantized lattice vibrations, i.e., the phonons, play a vital role. Phonons, much like photons, satisfy bosonic commutation relations, and therefore, various concepts well-known in quantum optics can be transferred to the emerging field of phononics. Examples are non-classical states
[...] Read more.
In solid-state physics, the quantized lattice vibrations, i.e., the phonons, play a vital role. Phonons, much like photons, satisfy bosonic commutation relations, and therefore, various concepts well-known in quantum optics can be transferred to the emerging field of phononics. Examples are non-classical states and, in particular, squeezed states. We discuss the generation of phonon squeezing by optically exciting a quantum dot and show that by excitation with detuned continuous wave laser fields, sequences of squeezed phonon wave packets are created, which are emitted from the quantum dot region into the surrounding material. Full article
(This article belongs to the Special Issue Quantum Optics and Quantum Information Processing)
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Open AccessReview All Optical Signal-Processing Techniques Utilizing Four Wave Mixing
Photonics 2015, 2(1), 200-213; https://doi.org/10.3390/photonics2010200
Received: 22 December 2014 / Accepted: 3 February 2015 / Published: 10 February 2015
Cited by 3 | Viewed by 2175 | PDF Full-text (843 KB) | HTML Full-text | XML Full-text
Abstract
Four Wave Mixing (FWM) based optical signal-processing techniques are reviewed. The use of FWM in arithmetical operation like subtraction, wavelength conversion and pattern recognition are three key parts discussed in this paper after a brief introduction on FWM and its comparison with other
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Four Wave Mixing (FWM) based optical signal-processing techniques are reviewed. The use of FWM in arithmetical operation like subtraction, wavelength conversion and pattern recognition are three key parts discussed in this paper after a brief introduction on FWM and its comparison with other nonlinear mixings. Two different approaches to achieve correlation are discussed, as well as a novel technique to realize all optical subtraction of two optical signals. Full article
(This article belongs to the Special Issue Nonlinear Fiber Optics)
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Open AccessArticle Transverse Electromagnetic Mode Conversion for High-Harmonic Self-Probing Spectroscopy
Photonics 2015, 2(1), 184-199; https://doi.org/10.3390/photonics2010184
Received: 25 December 2014 / Accepted: 30 January 2015 / Published: 10 February 2015
Cited by 5 | Viewed by 2374 | PDF Full-text (6834 KB) | HTML Full-text | XML Full-text
Abstract
We report on high-order harmonic (HHG) two-source interferometry (TSI) in molecular gases. We used a 0-\(\pi\) phase plate to create two bright spots at the focus of a lens by converting a Gaussian laser beam into a TEM please define \(_{01}\) Transverse Electromagnetic
[...] Read more.
We report on high-order harmonic (HHG) two-source interferometry (TSI) in molecular gases. We used a 0-\(\pi\) phase plate to create two bright spots at the focus of a lens by converting a Gaussian laser beam into a TEM please define \(_{01}\) Transverse Electromagnetic Mode. The two bright foci produce two synchronized HHG sources. One of them is used to probe on-going dynamics in the generating medium, while the other serves to heterodyne the signal. The interference of the emissions in the far–field gives access to the phase difference between the two sources. In self–probing HHG phase spectroscopy, one of the two sources is used as a reference while the other one probes some on goin dynamics in the generating medium. We first compute overlap integrals to investigate the mode conversion efficiency. We then establish a clear relation between the laser phase-front curvature and the far-field overlap of the two HHG beams. Both Fresnel diffraction calculations and an experimental lens position scan are used to reveal variations of the phase front inclination in each source. We show that this arrangement offers \(\frac{\lambda_{XUV}}{100}\) precision, enabling extremely sensitive phase measurements. Finally, we use this compact setup for TSI and measure phase variations across the molecular alignment revival of nitrogen and in vibrating sulfur hexafluoride. In both gases, the phase variations change sign around the ionization threshold of the investigated molecule. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Optimum Pump Pulse Duration for X-Ray Ar-Plasma Lasing
Photonics 2015, 2(1), 164-183; https://doi.org/10.3390/photonics2010164
Received: 22 December 2014 / Accepted: 29 January 2015 / Published: 10 February 2015
Cited by 4 | Viewed by 1691 | PDF Full-text (542 KB) | HTML Full-text | XML Full-text
Abstract
In plasma-driven X-ray lasers, it is critical to optimize the duration and time delay between pump pulses. In this study, we have done parametric simulations in order to systematically investigate the optimum time configuration of pump pulses. Here, we are mainly interested in
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In plasma-driven X-ray lasers, it is critical to optimize the duration and time delay between pump pulses. In this study, we have done parametric simulations in order to systematically investigate the optimum time configuration of pump pulses. Here, we are mainly interested in soft X-ray lasers created using a Ar target irradiated with laser pulses, which operate at a wavelength \(\lambda=46.9\) nm in the \(2p^5 3p^1(J=0)\rightarrow 2p^5 3s^1(J=1)\) laser transition. It is shown that the optimum time scale required to achieve Ne-like ions, as well as the time required to generate a population inversion depend on the combined effect of the electron temperature and electron density. The electron density and temperature are respectively a factor of \(\approx\)\(2.1\)- and \(\approx\)\(5\)-times higher in the case of a short pulse of \(0.1\) ps in comparison to a long pulse of 1,000 ps (at a constant fluence). The most effective lasing happens with short pulses with a pulse duration comparable to the total relaxation time from the upper level, namely \(\Delta\tau_p\leq35\) ps. Power laws to predict the optimum laser intensity to achieve Ne-like \(Ar^{+8}\) are obtained. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Single Element-Based Dual Focused Photoacoustic Microscopy
Photonics 2015, 2(1), 156-163; https://doi.org/10.3390/photonics2010156
Received: 14 January 2015 / Revised: 25 January 2015 / Accepted: 30 January 2015 / Published: 3 February 2015
Cited by 4 | Viewed by 1734 | PDF Full-text (456 KB) | HTML Full-text | XML Full-text
Abstract
We present a single element-based dual focused photoacoustic microscopy (PAM) that shows improved signal-to-noise ratio and lateral resolution compared to conventional single focused PAM in the out-of-focus region. This dual focused PAM is based on the novel design of a single element-based dual
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We present a single element-based dual focused photoacoustic microscopy (PAM) that shows improved signal-to-noise ratio and lateral resolution compared to conventional single focused PAM in the out-of-focus region. This dual focused PAM is based on the novel design of a single element-based dual focused transducer coupled with improved image reconstruction method using synthetic aperture dual focusing technique (SADFT). Polyvinylidene fluoride (PVDF) was used to fabricate the dual-focused transducer and phantom experiments were conducted to demonstrate the advantages of this novel transducer design. Experimental results obtained show that the signal-to-noise ratio and lateral resolution can be improved with a factor of 2X in the conventionally out-of-focus region using this technique. Full article
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Open AccessArticle Performance Analysis of Polarization Modulated DirectDetection Optical CDMA Systems over Turbulent FSO LinksModeled by the Gamma-Gamma Distribution
Photonics 2015, 2(1), 139-155; https://doi.org/10.3390/photonics2010139
Received: 8 January 2015 / Revised: 20 January 2015 / Accepted: 22 January 2015 / Published: 29 January 2015
Cited by 9 | Viewed by 2224 | PDF Full-text (404 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a theoretical study to characterize the transmission of optical code division multiple access (CDMA) systems deploying polarization shift keying (PolSK) over a free space optical (FSO) link under the impact of atmospheric turbulence. In our analysis, a novel transceiver architecture
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This paper proposes a theoretical study to characterize the transmission of optical code division multiple access (CDMA) systems deploying polarization shift keying (PolSK) over a free space optical (FSO) link under the impact of atmospheric turbulence. In our analysis, a novel transceiver architecture for atmospheric OCDMA FSO systems based on polarization modulation with direct detection is proposed and discussed. A detailed analytical model for PolSK-OCDMA systems over a turbulent FSO link is provided. Further, we derive a closed-form bit error ratio (BER) and outage probability expressions, taking into account the multiple-access interference (MAI), optical noise and the atmospheric turbulence effect on the FSO link modeled by the Gamma-Gamma distribution. Finally, the results of this study show the most significant parameters that degrade the transmission performance of the PolSK-OCDMA signal over FSO links and indicate that the proposed approach offers improved bit error ratio (BER) performances compared to the on-off-keying (OOK) modulation scheme in the presence of turbulence. Full article
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Open AccessArticle Design of a Label-Free, Distributed Bragg Grating Resonator Based Dielectric Waveguide Biosensor
Photonics 2015, 2(1), 124-138; https://doi.org/10.3390/photonics2010124
Received: 24 December 2014 / Accepted: 22 January 2015 / Published: 29 January 2015
Cited by 7 | Viewed by 4446 | PDF Full-text (990 KB) | HTML Full-text | XML Full-text
Abstract
In this work, we present a resonant, dielectric waveguide device based on distributed Bragg gratings for label-free biosensing applications. The refractive index sensitive optical transducer aims at improving the performance of planar waveguide grating sensor systems with limited Q-factor and dynamic range by
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In this work, we present a resonant, dielectric waveguide device based on distributed Bragg gratings for label-free biosensing applications. The refractive index sensitive optical transducer aims at improving the performance of planar waveguide grating sensor systems with limited Q-factor and dynamic range by combing the advantages of resonant cavities, such as a multitude of resonance peaks with high finesse, with the manageable complexity of waveguide grating couplers. The general sensor concept is introduced and supported by theoretical considerations as well as numerical simulations based on Coupled Mode Theory. In contrast to a single Bragg grating reflector, the presented Fabry-Pérot type distributed Bragg resonator exhibits an extended measurement range as well as relaxed fabrication tolerances. The resulting, relatively simple sensor structure can be fabricated with standard lithographic means and is independent of expensive light-sources and/or detectors, making an affordable but sensitive device, potentially suitable for point-of-care applications. Full article
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Open AccessArticle Quantum Path Interference and Multiple Electron Scattering in Soft X-Ray High-Order Harmonic Generation
Photonics 2015, 2(1), 104-123; https://doi.org/10.3390/photonics2010104
Received: 10 December 2014 / Accepted: 13 January 2015 / Published: 23 January 2015
Cited by 1 | Viewed by 2595 | PDF Full-text (976 KB) | HTML Full-text | XML Full-text
Abstract
High-order harmonic generation is an important mechanism to generate coherent radiation in the few–100-eV spectral range with ultrashort laser pulses. Moreover, a closer inspection of the measured spectra provides unique information about the underlying physics and allows deriving guidelines for improvements. The long-range
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High-order harmonic generation is an important mechanism to generate coherent radiation in the few–100-eV spectral range with ultrashort laser pulses. Moreover, a closer inspection of the measured spectra provides unique information about the underlying physics and allows deriving guidelines for improvements. The long-range modulation of the spectral envelope is linked to phase matching, and we will show how to improve it with a double-pulse excitation scheme. Additionally, the spectrum contains only every fourth harmonic, which can be well explained by the quantum interference of multiple scattered electrons, and two dominant electron trajectories were selected by X-ray parametric interaction. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Photo-Ionization of Noble Gases: A Demonstration of Hybrid Coupled Channels Approach
Photonics 2015, 2(1), 93-103; https://doi.org/10.3390/photonics2010093
Received: 15 December 2014 / Accepted: 14 January 2015 / Published: 16 January 2015
Cited by 7 | Viewed by 2146 | PDF Full-text (826 KB) | HTML Full-text | XML Full-text
Abstract
We present here an application of the recently developed hybrid coupled channels approach to study photo-ionization of noble gas atoms: Neon and Argon. We first compute multi-photon ionization rates and cross-sections for these inert gas atoms with our approach and compare them with
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We present here an application of the recently developed hybrid coupled channels approach to study photo-ionization of noble gas atoms: Neon and Argon. We first compute multi-photon ionization rates and cross-sections for these inert gas atoms with our approach and compare them with reliable data available from R-matrix Floquet theory. The good agreement between coupled channels and R-matrix Floquet theory show that our method treats multi-electron systems on par with the well established R-matrix theory. We then apply the time dependent surface flux (tSURFF) method with our approach to compute total and angle resolved photo-electron spectra from Argon with linearly and circularly polarized 12 nm wavelength laser fields, a typical wavelength available from Free Electron Lasers (FELs). Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessReview Electron Interference in Molecular Circular Polarization Attosecond XUV Photoionization
Photonics 2015, 2(1), 71-92; https://doi.org/10.3390/photonics2010071
Received: 3 December 2014 / Accepted: 8 January 2015 / Published: 12 January 2015
Cited by 2 | Viewed by 1915 | PDF Full-text (1527 KB) | HTML Full-text | XML Full-text
Abstract
Two-center electron interference in molecular attosecond photoionization processes is investigated from numerical solutions of time-dependent Schrödinger equations. Both symmetric H\(_2^+\) and nonsymmetric HHe\(^{2+}\) one electron diatomic systems are ionized by intense attosecond circularly polarized XUV laser pulses. Photoionization of these molecular ions shows
[...] Read more.
Two-center electron interference in molecular attosecond photoionization processes is investigated from numerical solutions of time-dependent Schrödinger equations. Both symmetric H\(_2^+\) and nonsymmetric HHe\(^{2+}\) one electron diatomic systems are ionized by intense attosecond circularly polarized XUV laser pulses. Photoionization of these molecular ions shows signature of interference with double peaks (minima) in molecular attosecond photoelectron energy spectra (MAPES) at critical angles \(\vartheta_c\) between the molecular \(\textbf{R}\) axis and the photoelectron momentum \(\textbf{p}\). The interferences are shown to be a function of the symmetry of electronic states and the interference patterns are sensitive to the molecular orientation and pulse polarization. Such sensitivity offers possibility for imaging of molecular structure and orbitals. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Toward the Extreme Ultra Violet Four Wave Mixing Experiments: From Table Top Lasers to Fourth Generation Light Sources
Photonics 2015, 2(1), 57-70; https://doi.org/10.3390/photonics2010057
Received: 13 December 2014 / Accepted: 8 January 2015 / Published: 12 January 2015
Cited by 1 | Viewed by 1575 | PDF Full-text (642 KB) | HTML Full-text | XML Full-text
Abstract
Three different Transient Grating setups are presented, with pulsed and continuous wave probe at different wavelengths, ranging from infrared to the extreme ultra violet region. Both heterodyne and homodyne detections are considered. Each scheme introduces variations with respect to the previous one, allowing
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Three different Transient Grating setups are presented, with pulsed and continuous wave probe at different wavelengths, ranging from infrared to the extreme ultra violet region. Both heterodyne and homodyne detections are considered. Each scheme introduces variations with respect to the previous one, allowing moving from classical table top laser experiments towards a new four wave mixing scheme based on free electron laser radiation. A comparison between the various setups and the first results from extreme ultra violet transient grating experiments is also discussed. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Liquid Carbon Reflectivity at 19 nm
Photonics 2015, 2(1), 50-56; https://doi.org/10.3390/photonics2010050
Received: 15 December 2014 / Accepted: 5 January 2015 / Published: 9 January 2015
Cited by 1 | Viewed by 1826 | PDF Full-text (424 KB) | HTML Full-text | XML Full-text
Abstract
We hereby report on a pump-probe reflectivity experiment conducted on amorphous carbon, using a 780 nm laser as a pump and a 19 nm FEL emission as probe. Measurements were performed at 50 degrees with respect to the surface normal to have an
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We hereby report on a pump-probe reflectivity experiment conducted on amorphous carbon, using a 780 nm laser as a pump and a 19 nm FEL emission as probe. Measurements were performed at 50 degrees with respect to the surface normal to have an un-pumped reflectivity higher than 0.5%. A sub-10 fs time synchronization error could be obtained exploiting the nearly jitter-free capabilities of FERMI. EUV FEL-based experiments open the way to study the behaviour of a liquid carbon phase being unaffected by plasma screening. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessReview Recent Developments in UV Optics for Ultra-Short, Ultra-Intense Coherent Light Sources
Photonics 2015, 2(1), 40-49; https://doi.org/10.3390/photonics2010040
Received: 19 December 2014 / Accepted: 4 January 2015 / Published: 8 January 2015
Cited by 6 | Viewed by 1826 | PDF Full-text (552 KB) | HTML Full-text | XML Full-text
Abstract
With the advent of Free Electron Lasers and general UV ultra-short, ultra-intense sources, optics needed to transport such radiation have evolved significantly to standard UV optics. Problems like surface damage, wavefront preservation, beam splitting, beam shaping, beam elongation (temporal stretching) pose new challenges
[...] Read more.
With the advent of Free Electron Lasers and general UV ultra-short, ultra-intense sources, optics needed to transport such radiation have evolved significantly to standard UV optics. Problems like surface damage, wavefront preservation, beam splitting, beam shaping, beam elongation (temporal stretching) pose new challenges for the design of beam transport systems. These problems lead to a new way to specify optics, a new way to use diffraction gratings, a search for new optical coatings, to tighter and tighter polishing requirements for mirrors, and to an increased use of adaptive optics. All these topics will be described in this review article, to show how optics could really be the limiting factor for future development of these new light sources. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle X-Optogenetics and U-Optogenetics: Feasibility and Possibilities
Photonics 2015, 2(1), 23-39; https://doi.org/10.3390/photonics2010023
Received: 22 November 2014 / Accepted: 30 December 2014 / Published: 7 January 2015
Cited by 7 | Viewed by 2554 | PDF Full-text (860 KB) | HTML Full-text | XML Full-text
Abstract
Optogenetics is an established technique that uses visible light to modulate membrane voltage in neural cells. Although optogenetics allows researchers to study parts of the brain like never before, it is limited because it is invasive, and visible light cannot travel very deeply
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Optogenetics is an established technique that uses visible light to modulate membrane voltage in neural cells. Although optogenetics allows researchers to study parts of the brain like never before, it is limited because it is invasive, and visible light cannot travel very deeply into tissue. This paper proposes two new techniques that remedy these challenges. The first is x-optogenetics, which uses visible light-emitting nanophosphors stimulated by focused x-rays. X-rays can penetrate much more deeply than infrared light and allow for nerve cell stimulation in any part of the brain. The second is u-optogenetics, which is an application of sonoluminescence to optogenetics. Such a technique uses ultrasound waves instead of x-rays to induce light emission, so there would be no introduction of radiation. However, the tradeoff is that the penetration depth of ultrasound is less than that of x-ray. The key issues affecting feasibility are laid out for further investigation into both x-optogenetics and u-optogenetics. Full article
(This article belongs to the Special Issue Biomedical Optics and Optical Imaging)
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Open AccessEditorial Acknowledgement to Reviewers of Photonics in 2014
Photonics 2015, 2(1), 21-22; https://doi.org/10.3390/photonics2010021
Received: 7 January 2015 / Accepted: 7 January 2015 / Published: 7 January 2015
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Abstract
The editors of Photonics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...] Full article
Open AccessArticle Quantum Magneto-Optics in Graphene
Photonics 2015, 2(1), 13-20; https://doi.org/10.3390/photonics2010013
Received: 11 December 2014 / Accepted: 25 December 2014 / Published: 5 January 2015
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Abstract
The optical conductivity of graphene in quantizing magnetic fields is studied. Both dynamical conductivities, longitudinal and Hall’s, are analytically evaluated. The conductivity peaks are explained in terms of electron transitions. The optical transitions obey the selection rule with Δn = 1 for
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The optical conductivity of graphene in quantizing magnetic fields is studied. Both dynamical conductivities, longitudinal and Hall’s, are analytically evaluated. The conductivity peaks are explained in terms of electron transitions. The optical transitions obey the selection rule with Δn = 1 for the Landau number n. The light transmission and Faraday rotation in the quantizing magnetic fields are calculated. Full article
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Open AccessArticle Smart Laser Interferometer with Electrically Tunable Lenses for Flow Velocity Measurements through Disturbing Interfaces
Photonics 2015, 2(1), 1-12; https://doi.org/10.3390/photonics2010001
Received: 6 November 2014 / Accepted: 29 December 2014 / Published: 5 January 2015
Cited by 3 | Viewed by 1917 | PDF Full-text (389 KB) | HTML Full-text | XML Full-text
Abstract
Interferometric velocity measurements are of great importance at flow investigations. However, the laser beams can be distorted at the interfaces between optical media of different refractive indices. Temporal fluctuations of these distortions will cause a deterioration of the laser interferometer signals. We have
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Interferometric velocity measurements are of great importance at flow investigations. However, the laser beams can be distorted at the interfaces between optical media of different refractive indices. Temporal fluctuations of these distortions will cause a deterioration of the laser interferometer signals. We have harnessed the power of programmable photonics devices to eliminate this signal deterioration. Non-invasive flow velocity measurements through a rapidly fluctuating media interface with large strokes of about 100 microns are presented. Our work represents a paradigm shift for interferometric velocity measurement techniques from using static to dynamic optical elements. Full article
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