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Photonics, Volume 4, Issue 1 (March 2017)

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Editorial

Jump to: Research, Review

Open AccessEditorial Acknowledgement to Reviewers of Photonics in 2016
Photonics 2017, 4(1), 4; doi:10.3390/photonics4010004
Received: 10 January 2017 / Accepted: 10 January 2017 / Published: 10 January 2017
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Abstract The editors of Photonics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article

Research

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Open AccessArticle Generation and Detection of Continuous Variable Quantum Vortex States via Compact Photonic Devices
Photonics 2017, 4(1), 2; doi:10.3390/photonics4010002
Received: 10 October 2016 / Revised: 20 December 2016 / Accepted: 29 December 2016 / Published: 3 January 2017
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Abstract
A quantum photonic circuit with the ability to produce continuous variable quantum vortex states is proposed. This device produces two single-mode squeezed states which go through a Mach-Zehnder interferometer where photons are subtracted by means of weakly coupled directional couplers towards ancillary waveguides.
[...] Read more.
A quantum photonic circuit with the ability to produce continuous variable quantum vortex states is proposed. This device produces two single-mode squeezed states which go through a Mach-Zehnder interferometer where photons are subtracted by means of weakly coupled directional couplers towards ancillary waveguides. The detection of a number of photons in these modes heralds the production of a quantum vortex. Likewise, a measurement system of the order and handedness of quantum vortices is introduced and the performance of both devices is analyzed in a realistic scenario by means of the Wigner function. These devices open the possibility of using the quantum vortices as carriers of quantum information. Full article
(This article belongs to the Special Issue Quantum Photonics Circuits)
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Open AccessArticle Statistical Model and Performance Analysis of a Novel Multilevel Polarization Modulation in Local “Twisted” Fibers
Photonics 2017, 4(1), 5; doi:10.3390/photonics4010005
Received: 6 November 2016 / Revised: 20 January 2017 / Accepted: 20 January 2017 / Published: 26 January 2017
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Abstract
Transmission demand continues to grow and higher capacity optical communication systems are required to economically meet this ever-increasing need for communication services. This article expands and deepens the study of a novel optical communication system for high-capacity Local Area Networks (LANs), based on
[...] Read more.
Transmission demand continues to grow and higher capacity optical communication systems are required to economically meet this ever-increasing need for communication services. This article expands and deepens the study of a novel optical communication system for high-capacity Local Area Networks (LANs), based on twisted optical fibers. The complete statistical behavior of this system is shown, designed for more efficient use of the fiber single-channel capacity by adopting an unconventional multilevel polarization modulation (called “bands of polarization”). Starting from simulative results, a possible reference mathematical model is proposed. Finally, the system performance is analyzed in the presence of shot-noise (coherent detection) or thermal noise (direct detection). Full article
(This article belongs to the Special Issue Optical Networks for Communications)
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Open AccessArticle Element Selective Probe of the Ultra-Fast Magnetic Response to an Element Selective Excitation in Fe-Ni Compounds Using a Two-Color FEL Source
Photonics 2017, 4(1), 6; doi:10.3390/photonics4010006
Received: 18 December 2016 / Revised: 18 January 2017 / Accepted: 20 January 2017 / Published: 26 January 2017
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Abstract
The potential of the two-color mode implemented at the FERMI free-electron laser (FEL) source for pumping and probing selectively different atomic species has been demonstrated by time-resolved scattering experiments with permalloy (FeNi alloy) and NiFe2O4 samples. We monitored the ultra-fast
[...] Read more.
The potential of the two-color mode implemented at the FERMI free-electron laser (FEL) source for pumping and probing selectively different atomic species has been demonstrated by time-resolved scattering experiments with permalloy (FeNi alloy) and NiFe2O4 samples. We monitored the ultra-fast demagnetization of Ni induced by the pump FEL pulse, by tuning the linearly-polarized FEL probe pulse to the Ni-3p resonance and measuring the scattered intensity in the transverse magneto-optical Kerr effect geometry. The measurements were performed by varying the intensity of the FEL pump pulse, tuning its wavelength to and off of the Fe-3p resonance, and by spanning the FEL probe pulse delays across the 300–900 fs range. The obtained results have evidenced that for the case of NiFe2O4, there is a sensible difference in the magnetic response at the Ni site when the pump pulse causes electronic excitations at the Fe site. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Optical Analysis of the Oils Obtained from Acrocomia aculeata (Jacq.) Lodd: Mapping Absorption-Emission Profiles in an Induced Oxidation Process
Photonics 2017, 4(1), 3; doi:10.3390/photonics4010003
Received: 29 November 2016 / Revised: 29 December 2016 / Accepted: 4 January 2017 / Published: 6 January 2017
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Abstract
Acrocomia aculeata is a palm tree typical of the Brazilian savanna. Oils extracted from the pulp and kernel of Acrocomia aculeata fruits have gained considerable attention mainly due to their nutritional and medicinal features. Despite their potential applications, a detailed analysis of their
[...] Read more.
Acrocomia aculeata is a palm tree typical of the Brazilian savanna. Oils extracted from the pulp and kernel of Acrocomia aculeata fruits have gained considerable attention mainly due to their nutritional and medicinal features. Despite their potential applications, a detailed analysis of their oxidative stability is still needed. The present study shows a close analysis of the oxidative stability of the oils obtained from the kernel and pulp of Acrocomia aculeata fruits, evaluating the influence of the intrinsic antioxidants and the fatty acid composition on the oil’s thermal stability. A complete characterization of the physical-chemical and optical properties of the oils was performed. The results showed that 66% of the fatty acids present in the pulp oil are unsaturated, while 75% are saturated in the kernel oil. A higher content of intrinsic antioxidants was obtained in the pulp oil, and an induction period (at 110 °C) of 65 and 43 h was determined for the pulp and kernel oil, respectively. Additionally, oil absorption increases due to the formation of degradation products, and a new fluorescent compound was formed during the oil oxidation process at 110 °C. Even though the pulp presented a high content of unsaturated fatty acids, the pulp oil was more stable than the kernel oil due to its higher content of intrinsic antioxidant, especially carotenoids. The results also demonstrated that oil oxidation can be optically determined by analyzing the absorption at 232 and 270 nm, as well as the emission at 424 nm. Full article
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Open AccessArticle Dipole Emission to Surface Plasmon-Coupled Enhanced Transmission in Diamond Substrates with Nitrogen Vacancy Center- Near the Surface
Photonics 2017, 4(1), 10; doi:10.3390/photonics4010010
Received: 21 December 2016 / Revised: 25 January 2017 / Accepted: 6 February 2017 / Published: 10 February 2017
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Abstract
For distances less 10 nm, a total energy transfer occurs from a quantum emitter to a nearby metallic surface, producing evanescent surface waves that are plasmonic in nature. When investigating a metallic nanohole supported on an optically dense substrate (such as diamond with
[...] Read more.
For distances less 10 nm, a total energy transfer occurs from a quantum emitter to a nearby metallic surface, producing evanescent surface waves that are plasmonic in nature. When investigating a metallic nanohole supported on an optically dense substrate (such as diamond with nitrogen vacancy center), the scattering occurred preferentially from the diamond substrate towards the air for dipole distances less 10 nm from the aperture. In addition, an enhancement to the dipole’s radiative decay rate was observed when resonance of the aperture matched the emitters wavelength. The relationship between an emitter and a nearby resonant aperture is shown to be that of the resonance energy transfer where the emitter acts as a donor and the hole as an acceptor. In conjunction with the preferential scattering behavior, this has led to the proposed device that operates in transmission mode, eliminating the need for epi-illumination techniques and optically denser than air superstrates in the collection cycle, hence making the design simpler and more suitable for miniaturization. A design criterion for the surface grating is also proposed to improve the performance, where the period of the grating differs significantly from the wavelength of the surface plasmon polaritons. Response of the proposed device is further studied with respect to changes in nitrogen vacancy’s position and its dipolar orientation to identify the crystallographic planes of diamond over which the performance of the device is maximized. Full article
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Open AccessArticle Phase-Insensitive Scattering of Terahertz Radiation
Photonics 2017, 4(1), 7; doi:10.3390/photonics4010007
Received: 17 November 2016 / Accepted: 25 January 2017 / Published: 31 January 2017
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Abstract
The nonlinear interaction between Near-Infrared (NIR) and Terahertz pulses is principally investigated as a means for the detection of radiation in the hardly accessible THz spectral region. Most studies have targeted second-order nonlinear processes, given their higher efficiencies, and only a limited number
[...] Read more.
The nonlinear interaction between Near-Infrared (NIR) and Terahertz pulses is principally investigated as a means for the detection of radiation in the hardly accessible THz spectral region. Most studies have targeted second-order nonlinear processes, given their higher efficiencies, and only a limited number have addressed third-order nonlinear interactions, mainly investigating four-wave mixing in air for broadband THz detection. We have studied the nonlinear interaction between THz and NIR pulses in solid-state media (specifically diamond), and we show how the former can be frequency-shifted up to UV frequencies by the scattering from the nonlinear polarisation induced by the latter. Such UV emission differs from the well-known electric field-induced second harmonic (EFISH) one, as it is generated via a phase-insensitive scattering, rather than a sum- or difference-frequency four-wave-mixing process. Full article
(This article belongs to the Special Issue Ultrafast Photonics and Attosecond Sciences)
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Open AccessArticle Experimental Demonstration of an Electro-Absorption Modulated Laser for High-Speed Transmissions at 1.55-μm Window Using Digital Signal Processing
Photonics 2017, 4(1), 9; doi:10.3390/photonics4010009
Received: 14 December 2016 / Revised: 26 January 2017 / Accepted: 6 February 2017 / Published: 8 February 2017
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Abstract
We experimentally investigate the transmission performance of 56 Gb/s four-level pulse amplitude modulation (PAM-4) over 30-km standard single mode fiber (SMF) using a C-band EML for low-cost metro and short-reach wavelength division multiplexing (WDM) applications. Bit error rate (BER) performance below the HD-FEC
[...] Read more.
We experimentally investigate the transmission performance of 56 Gb/s four-level pulse amplitude modulation (PAM-4) over 30-km standard single mode fiber (SMF) using a C-band EML for low-cost metro and short-reach wavelength division multiplexing (WDM) applications. Bit error rate (BER) performance below the HD-FEC threshold is achieved for up to 30-km maximum reported distance without employing dispersion compensation fiber (DCF) in the link. Full article
(This article belongs to the Special Issue Optical Networks for Communications)
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Open AccessArticle Nonlinear Diffuse fs-Pulse Reflectometry of Harmonic Upconversion Nanoparticles
Photonics 2017, 4(1), 11; doi:10.3390/photonics4010011
Received: 14 December 2016 / Revised: 10 February 2017 / Accepted: 16 February 2017 / Published: 19 February 2017
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Abstract
Nonlinear diffuse femtosecond-pulse reflectometry is introduced as a powerful experimental tool for the unambiguous characterization of polar and non-polar point symmetry groups of harmonic upconversion nanoparticles. Using intense ultrashort 40 femtosecond laser pulses and an appropriate figure of merit (FOM), second and third
[...] Read more.
Nonlinear diffuse femtosecond-pulse reflectometry is introduced as a powerful experimental tool for the unambiguous characterization of polar and non-polar point symmetry groups of harmonic upconversion nanoparticles. Using intense ultrashort 40 femtosecond laser pulses and an appropriate figure of merit (FOM), second and third harmonic emission serve for the structural characterization of polar Yb-doped lithium niobate and non-polar titanium dioxide nanoparticles. The tool is capable of differentiating these two samples by FOM values that differ by up to 13 orders of magnitude. The general applicability to harmonic upconversion nanoparticles over a broad range of intensities and wavelength spectrum, is discussed. Full article
(This article belongs to the Special Issue Ultrafast Photonics and Attosecond Sciences)
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Open AccessArticle Novel Equalization Techniques for Space Division Multiplexing Based on Stokes Space Update Rule
Photonics 2017, 4(1), 12; doi:10.3390/photonics4010012
Received: 23 December 2016 / Revised: 12 February 2017 / Accepted: 16 February 2017 / Published: 20 February 2017
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Abstract
Space division multiplexing (SDM) is a promising technology that aims to overcome the capacity crunch of optical communications. In this paper, we introduce the multiple-input multiple-output (MIMO) Stokes Space Algorithm (SSA) implemented in frequency domain, a novel equalization technique for space division multiplexing
[...] Read more.
Space division multiplexing (SDM) is a promising technology that aims to overcome the capacity crunch of optical communications. In this paper, we introduce the multiple-input multiple-output (MIMO) Stokes Space Algorithm (SSA) implemented in frequency domain, a novel equalization technique for space division multiplexing (SDM). Although different papers have been published about the SSA and its MIMO implementation, we provide for the first time an analysis of the of the convergence speed and frequency offset of the SSA compared to the least mean square (LMS). SSA algorithm can deal with higher frequency offsets and linewidths than LMS, being suitable for optical communications with higher phase noise. SSA does not need pre-compensation of frequency offset, which can be compensated after equalization without penalties. On the other hand, due to reduced convergence speed, SSA requires longer training sequences than LMS. Full article
(This article belongs to the Special Issue Optical Networks for Communications)
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Open AccessArticle High-Speed, High-Performance DQPSK Optical Links with Reduced Complexity VDFE Equalizers
Photonics 2017, 4(1), 13; doi:10.3390/photonics4010013
Received: 15 January 2017 / Revised: 23 February 2017 / Accepted: 24 February 2017 / Published: 26 February 2017
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Abstract
Optical transmission technologies optimized for optical network segments sensitive to power consumption and cost, comprise modulation formats with direct detection technologies. Specifically, non-return to zero differential quaternary phase shift keying (NRZ-DQPSK) in deployed fiber plants, combined with high-performance, low-complexity electronic equalizers to compensate
[...] Read more.
Optical transmission technologies optimized for optical network segments sensitive to power consumption and cost, comprise modulation formats with direct detection technologies. Specifically, non-return to zero differential quaternary phase shift keying (NRZ-DQPSK) in deployed fiber plants, combined with high-performance, low-complexity electronic equalizers to compensate residual impairments at the receiver end, can be proved as a viable solution for high-performance, high-capacity optical links. Joint processing of the constructive and the destructive signals at the single-ended DQPSK receiver provides improved performance compared to the balanced configuration, however, at the expense of higher hardware requirements, a fact that may not be neglected especially in the case of high-speed optical links. To overcome this bottleneck, the use of partially joint constructive/destructive DQPSK equalization is investigated in this paper. Symbol-by-symbol equalization is performed by means of Volterra decision feedback-type equalizers, driven by a reduced subset of signals selected from the constructive and the destructive ports of the optical detectors. The proposed approach offers a low-complexity alternative for electronic equalization, without sacrificing much of the performance compared to the fully-deployed counterpart. The efficiency of the proposed equalizers is demonstrated by means of computer simulation in a typical optical transmission scenario. Full article
(This article belongs to the Special Issue Optical Networks for Communications)
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Open AccessArticle Design Study of Time-Preserving Grating Monochromators for Ultrashort Pulses in the Extreme-Ultraviolet and Soft X-Rays
Photonics 2017, 4(1), 14; doi:10.3390/photonics4010014
Received: 30 January 2017 / Revised: 23 February 2017 / Accepted: 27 February 2017 / Published: 1 March 2017
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Abstract
The design of grating-based instruments to handle and condition coherent ultrafast pulses in the extreme-ultraviolet is discussed. The main application of such instruments is the monochromatization of high-order laser harmonics and free-electron-laser pulses in the femtosecond time scale. Broad-band monochromators require the use
[...] Read more.
The design of grating-based instruments to handle and condition coherent ultrafast pulses in the extreme-ultraviolet is discussed. The main application of such instruments is the monochromatization of high-order laser harmonics and free-electron-laser pulses in the femtosecond time scale. Broad-band monochromators require the use of diffraction gratings at grazing incidence. A grating can be used for the spectral selection of ultrashort pulses without altering the pulse duration in a significant way, provided that the number of illuminated grooves is equal to the resolution. We discuss here the design conditions to be fulfilled by a grating monochromator that does not increase the pulse duration significantly longer than the Fourier limit. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Optical Klystron Enhancement to Self Amplified Spontaneous Emission at FERMI
Photonics 2017, 4(1), 15; doi:10.3390/photonics4010015
Received: 1 February 2017 / Accepted: 23 February 2017 / Published: 1 March 2017
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Abstract
The optical klystron enhancement to a self-amplified spontaneous emission free electron laser has been studied in theory and in simulations and has been experimentally demonstrated on a single-pass high-gain free electron laser, the FERMI FEL-1, in 2014. The main concept consists of two
[...] Read more.
The optical klystron enhancement to a self-amplified spontaneous emission free electron laser has been studied in theory and in simulations and has been experimentally demonstrated on a single-pass high-gain free electron laser, the FERMI FEL-1, in 2014. The main concept consists of two undulators separated by a dispersive section that converts the energy modulation induced in the first undulator in density modulation, enhancing the coherent harmonic generation in the first part of the second undulator. This scheme could be replicated in a multi-stage: the bunching is enhanced after each dispersive section, consistently reducing the saturation length. We have applied the multi-stage optical klystron (OK) scheme on the FEL-2 line at FERMI, whose layout includes three dispersive sections. Optimizing the strength of the dispersions allowed a significant increase of the self-amplified spontaneous emission (SASE) intensity in comparison to a single-stage OK and extending to the soft-X rays the OK enhanced SASE previously demonstrated on FEL-1. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle Experimental Evaluation of Impairments in Unrepeatered DP-16QAM Link with Distributed Raman Amplification
Photonics 2017, 4(1), 16; doi:10.3390/photonics4010016
Received: 13 January 2017 / Revised: 5 March 2017 / Accepted: 6 March 2017 / Published: 8 March 2017
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Abstract
The transmission impairments of a Raman amplified link using dual-polarization 16-quadrature amplitude modulation (DP-16QAM) are experimentally characterized. The impact of amplitude and phase noise on the signal due to relative intensity noise (RIN) transfer from the pump are compared for two pumping configurations:
[...] Read more.
The transmission impairments of a Raman amplified link using dual-polarization 16-quadrature amplitude modulation (DP-16QAM) are experimentally characterized. The impact of amplitude and phase noise on the signal due to relative intensity noise (RIN) transfer from the pump are compared for two pumping configurations: first-order backward pumping and bi-directional pumping. Experimental results indicate that with increased Raman backward pump power, though the optical signal-to-noise ratio (OSNR) is increased, so is the pump-induced amplitude and phase noise. The transmission performance is firstly improved by the enhanced OSNR at a low pump power until an optimum point is reached, and then the impairments due to pump-induced noise start to dominate. However, the introduction of a low pump power in the forward direction can further improve the system’s performance. Full article
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Open AccessArticle XUV Transient Absorption Spectroscopy: Probing Laser-Perturbed Dipole Polarization in Single Atom, Macroscopic, and Molecular Regimes
Photonics 2017, 4(1), 17; doi:10.3390/photonics4010017
Received: 9 February 2017 / Accepted: 6 March 2017 / Published: 8 March 2017
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Abstract
We employ an extreme ultraviolet (XUV) pulse to impulsively excite dipole polarization in atoms or molecules, which corresponds to coherently prepared superposition of excited states. A delayed near infrared (NIR) pulse then perturbs the fast evolving polarization, and the resultant absorbance change is
[...] Read more.
We employ an extreme ultraviolet (XUV) pulse to impulsively excite dipole polarization in atoms or molecules, which corresponds to coherently prepared superposition of excited states. A delayed near infrared (NIR) pulse then perturbs the fast evolving polarization, and the resultant absorbance change is monitored in dilute helium, dense helium, and sulfur hexafluoride (SF6) molecules. We observe and quantify the time-dependence of various transient phenomena in helium atoms,includinglaser-inducedphase(LIP),time-varying(AC)Starkshift,quantumpathinterference, and laser-induced continuum structure. In the case of dense helium targets, we discuss nonlinear macroscopic propagation effects pertaining to LIP and resonant pulse propagation, which accoun tfor the appearance of new spectral features in transient lineshapes. We then use tunable NIR photons to demonstrate the wavelength dependence of the transient laser induced effects. In the case of molecular polarization experiment in SF6, we show suppression of XUV photoabsorption corresponding to inter-valence transitions in the presence of a strong NIR field. In each case, the temporal evolution of transient absorption spectra allows us to observe and understand the transient laser induced modifications of the electronic structure of atoms and molecules. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Open AccessArticle A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance
Photonics 2017, 4(1), 18; doi:10.3390/photonics4010018
Received: 14 February 2017 / Revised: 4 March 2017 / Accepted: 8 March 2017 / Published: 10 March 2017
Cited by 2 | PDF Full-text (2316 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we numerically demonstrate a two-layer circular lattice photonic crystal fiber (PCF) biosensor based on the principle of surface plasmon resonance (SPR). The finite element method (FEM) with circular perfectly matched layer (PML) boundary condition is applied to evaluate the performance
[...] Read more.
In this paper, we numerically demonstrate a two-layer circular lattice photonic crystal fiber (PCF) biosensor based on the principle of surface plasmon resonance (SPR). The finite element method (FEM) with circular perfectly matched layer (PML) boundary condition is applied to evaluate the performance of the proposed sensor. A thin gold layer is deposited outside the PCF structure, which acts as the plasmonic material for this design. The sensing layer (analyte) is implemented in the outermost layer, which permits easy and more practical fabrication process compared to analyte is put inside the air holes. It is demonstrated that, at gold layer thickness of 40 nm, the proposed sensor shows maximum sensitivity of 2200 nm/RIU using the wavelength interrogation method in the sensing range between 1.33–1.36. Besides, using an amplitude interrogation method, a maximum sensitivity of 266 RIU−1 and a maximum sensor resolution of 3.75 × 10−5 RIU are obtained. We also discuss how phase matching points are varied with different fiber parameters. Owing to high sensitivity and simple design, the proposed sensor may find important applications in biochemical and biological analyte detection. Full article
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Open AccessArticle Echo-Enabled Harmonic Generation Studies for the FERMI Free-Electron Laser
Photonics 2017, 4(1), 19; doi:10.3390/photonics4010019
Received: 6 February 2017 / Revised: 6 March 2017 / Accepted: 8 March 2017 / Published: 14 March 2017
Cited by 2 | PDF Full-text (2094 KB) | HTML Full-text | XML Full-text
Abstract
Studying ultrafast processes on the nanoscale with element specificity requires a powerful femtosecond source of tunable extreme-ultraviolet (XUV) or x-ray radiation, such as a free-electron laser (FEL). Current efforts in FEL development are aimed at improving the wavelength tunability and multicolor operation, which
[...] Read more.
Studying ultrafast processes on the nanoscale with element specificity requires a powerful femtosecond source of tunable extreme-ultraviolet (XUV) or x-ray radiation, such as a free-electron laser (FEL). Current efforts in FEL development are aimed at improving the wavelength tunability and multicolor operation, which will potentially lead to the development of new characterization techniques offering a higher chemical sensitivity and improved spatial resolution. One of the most promising approaches is the echo-enabled harmonic generation (EEHG), where two external seed lasers are used to precisely control the spectro-temporal properties of the FEL pulse. Here, we study the expected performance of EEHG at the FERMI FEL, using numerical simulations. We show that, by employing the existing FERMI layout with minor modifications, the EEHG scheme will be able to produce gigawatt peak-power pulses at wavelengths as short as 5 nm. We discuss some possible detrimental effects that may affect the performance of EEHG and compare the results to the existing double-stage FEL cascade, currently in operation at FERMI. Finally, our simulations show that, after substantial machine upgrades, EEHG has the potential to deliver coherent multicolor pulses reaching wavelengths as short as 3 nm, enabling x-ray pump–x-ray probe experiments in the water window. Full article
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
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Review

Jump to: Editorial, Research

Open AccessReview Future Scenarios for Software-Defined Metro and Access Networks and Software-Defined Photonics
Photonics 2017, 4(1), 1; doi:10.3390/photonics4010001
Received: 16 November 2016 / Revised: 21 December 2016 / Accepted: 28 December 2016 / Published: 3 January 2017
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Abstract
In recent years, architectures, devices, and components in telecommunication networks have been challenged by evolutionary and revolutionary factors which are drastically changing the traffic features. Most of these changes imply the need for major re-configurability and programmability not only in data-centers and core
[...] Read more.
In recent years, architectures, devices, and components in telecommunication networks have been challenged by evolutionary and revolutionary factors which are drastically changing the traffic features. Most of these changes imply the need for major re-configurability and programmability not only in data-centers and core networks, but also in the metro-access segment. In a wide variety of contexts, this necessity has been addressed by the proposed introduction of the innovative paradigm of software-defined networks (SDNs). Several solutions inspired by the SDN model have been recently proposed also for metro and access networks, where the adoption of a new generation of software-defined reconfigurable integrated photonic devices is highly desirable. In this paper, we review the possible future application scenarios for software-defined metro and access networks and software-defined photonics (SDP), on the base of analytics, statistics, and surveys. This work describes the reasons underpinning the presented radical change of paradigm and summarizes the most significant solutions proposed in literature, with a specific emphasis to physical-layer reconfigurable networks and a focus on both architectures and devices. Full article
(This article belongs to the Special Issue Optical Networks for Communications)
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Open AccessReview Ultrafast Laser Pulses for Structuring Materials at Micro/Nano Scale: From Waveguides to Superhydrophobic Surfaces
Photonics 2017, 4(1), 8; doi:10.3390/photonics4010008
Received: 6 December 2016 / Accepted: 25 January 2017 / Published: 31 January 2017
Cited by 1 | PDF Full-text (5614 KB) | HTML Full-text | XML Full-text
Abstract
The current demand for fabricating optical and photonic devices displaying high performance, using low-cost and time-saving methods, prompts femtosecond (fs)-laser processing as a promising methodology. High and low repetition femtosecond lasers enable surface and/or bulk modification of distinct materials, which can be used
[...] Read more.
The current demand for fabricating optical and photonic devices displaying high performance, using low-cost and time-saving methods, prompts femtosecond (fs)-laser processing as a promising methodology. High and low repetition femtosecond lasers enable surface and/or bulk modification of distinct materials, which can be used for applications ranging from optical waveguides to superhydrophobic surfaces. Herein, some fundamental aspects of fs-laser processing of materials, as well as the basics of their most common experimental apparatuses, are introduced. A survey of results on polymer fs-laser processing, resulting in 3D waveguides, electroluminescent structures and active hybrid-microstructures for luminescence or biological microenvironments is presented. Similarly, results of fs-laser processing on glasses, gold and silicon to produce waveguides containing metallic nanoparticles, analytical chemical sensors and surface with modified features, respectively, are also described. The complexity of fs-laser micromachining involves precise control of material properties, pushing ultrafast laser processing as an advanced technique for micro/nano devices. Full article
(This article belongs to the Special Issue Ultrafast Photonics and Attosecond Sciences)
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