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Highly Wavelength-Selective Asymmetric Dual-core Liquid Photonic Crystal Fiber Polarization Splitter

Bahaa Younis, Ahmed Heikal, Mohamed Hameed, and Salah Obayya

Doc ID: 320079 Received 18 Jan 2018; Accepted 14 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: An asymmetric dual core photonic crystal fiber (ADC-PCF) wavelength selective polarization splitter is reported and analyzed. The left core of the DC-PCF is surrounded by nematic liquid crystal (NLC) infiltrated holes in order to control the wavelength at which coupling occurs between the dual cores of the proposed design. Moreover, the suggested structure can be tuned to split out the x and y-polarized modes at the two telecommunication wavelengths λ=1.3 μm and λ=1.55 μm. The geometrical parameters of the reported splitter are studied by full vectorial finite difference method (FVFDM) via Lumerical software package to achieve high wavelength selectivity with device length of 5.678 mm at λ=1.3 μm. Further, the power coupling characteristics of the reported device are studied which ensures that the ADC-PCF splitter has a very narrow bandwidth of approximately 3 nm around wavelengths of 1.3 μm and 1.55 μm. Therefore, the suggested design can be considered as a very good candidate to be used in the integrated photonic devices.

Light harvesting optimization in two-dimensional TMDC monolayer heterostructures

Narges Ansari and Farinaz Ghorbani

Doc ID: 315307 Received 11 Dec 2017; Accepted 14 Mar 2018; Posted 16 Mar 2018  View: PDF

Abstract: Heterostructures of two-dimensional transition metal dichalcogenides (TMDCs) have recently received upsurge attention for application in optoelectronics. In this paper, we demonstrate efficient absorber heterostructures in a form of air/hetero-TMDCs/substrate with various TMDC monolayers (MoSe₂, WSe₂, MoS₂ and WS₂). The dielectric permittivity of individual TMDC monolayers is determined using the Lorentz model. The absorption response of designed hetero-TMDCs is determined by using the transfer matrix method (TMM). The effects of light polarization, angle of incident and substrate on the absorption response are investigated. Finally, MoSe₂/MoS₂ and WS₂/MoSe₂ heterostructures on the SiO₂ (90 nm)/Si substrate are found to have absorption over 30% in a broadband wavelength range and in a wide incident angle, both useful designs for optoelectronic applications.

Surface passivation of silicon photonic devices with high surface-to-volume-ratio nanostructures

Ahmed S. Mayet, Hilal Cansizoglu, Yang Gao, SOROUSH GHANDIPARSI, Ahmet Kaya, Badriyah Alhalaili, Toshishige YAMADA, Ekaterina Ponizovskaya Devine, ALY F. ELREFAIE, Shih-Yuan Wang, M. Saif Islam, and CESAR BARTOLO-PEREZ

Doc ID: 319911 Received 16 Jan 2018; Accepted 14 Mar 2018; Posted 16 Mar 2018  View: PDF

Abstract: Recently high speed and high efficiency silicon photodiode (PD) has been demonstrated by enabling light trapping micro-/nanostructured holes. While attractive for light manipulation, these high surface-to-volume-ratio nanostructures which are created by top-down dry etching processes can also bring other challenges such as creating silicon surface damages and crystalline defects. In order to reduce the dark current level and minimize the surface recombination, successful passivation is a vital step to achieve the ultimate performance of the silicon photodiode based on the photon-trapping structures. In this paper, we present and compare several effective silicon surface passivation schemes including plasma enhanced chemical vapor deposited (PECVD) SiO2 and Si3N4, hydrofluoric acid (HF) treatment, thermal oxidation, and low ion energy dry etch. These passivation techniques can reduce the dark current by more than four orders of magnitude, bringing it down to nano ampere level. Among these passivation schemes, HF treatment is relatively simple and cost-effective; while other techniques may alter the light trapping characteristics of silicon photodiodes to some extent, thus affecting its external quantum efficiency. These passivation techniques discussed in this paper are CMOS compatible and can be also applied to other silicon photonic devices such as photovoltaics.

Pulsed coherent population trapping spectroscopy inmicrofabricated Cs-Ne vapor cells

Rodolphe Boudot, Vincent Maurice, Christophe Gorecki, and emeric declercq

Doc ID: 315622 Received 14 Dec 2017; Accepted 12 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: Pulsed coherent population trapping (CPT) spectroscopy is applied in buffer-gas filled Cs-Ne vapor microfabricated cells. The properties of the Ramsey-CPT clock transition central fringe (linewidth, signal, amplitude, contrast) is studied versus several experimental parameters including the Ramsey sequence or the input laser intensity and are compared to those obtained in the conventional continuous (CW) interrogation mode. In the pulsed case, the central fringe linewidth is found to exhibit a visible power broadening and measured to be commonly narrower than the expected Ramsey line-width given by 1 / ( 2 T R ), with T R the free-evolution time, for short values of TR . The microwave hyperfine coherence lifetime T2 in the Cs-Ne microcells is measured to be in the 50-500 µs range. Its dependence to the buffer gas pressure or cell temperature is briefly studied

Surface plasmon field enhancement: Excitaction byshort pulse or narrow beam of light

Jesus Gutiérrez Villarreal, Jorge Gaspar-Armenta, and Luis Mayoral Astorga

Doc ID: 320190 Received 19 Jan 2018; Accepted 12 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: With the advance of laser technology, there are many applications exciting surface plasmons with very short pulses of light. We perform a quantitative study of field amplification of surface plasmons excited by short light pulses. The dependence of the maximum intensity of the electromagnetic fields at the metal-dielectric interface as a function of the pulse duration are obtained. A Gaussian light pulse is used as the excitation source and it is computed the propagation of this pulse on an Attenuated Total Reflection system for the Kretschmann geometry. The field enhancement produced by the pulse is about 80% of the steady state case when the width of the pulse is half the decay time of the surface plasmon, and gets close to 95% when the width is equal to the time decay. We obtain an approximate expression for the field amplification as a function of the pulse width that is close to the exact calculation. Additionally, it is obtained an approximate expression for the enhancement of the fields when surface plasmons are excited with a narrow spatial width of a beam.

A Single-Shot Multispectral Imager Using Spatially Multiplexed Fourier Spectral Filters

Chuan Ni, Jie Jia, Matthew Howard, Keigo Hirakawa, and Andrew Sarangan

Doc ID: 309570 Received 19 Oct 2017; Accepted 11 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: We demonstrate a single-shot multispectral imaging system using a fundamentally different approach compared to present-day methods. Conventional multispectral imagers utilize narrowband spectral filters, which makes the system application-specific. By using filters with sinusoidally varying transmittance, known as Fourier filters, we demonstrate an application-agnostic multispectral system. We designed and fabricated this Fourier filter array, integrated it with a commercial CCD image sensor, and acquired and reconstructed the spectral information from multiple targets. Compared to narrowband multispectral imagers, this system generalizes well to applications where we lack a priori knowledge of the spectral content of the scene, which makes it a versatile acquisition device for a wide range of applications.

Dynamics of laser induced defects by multiple femtosecond pulses in potassium dihydrogen phosphate crystals

Marie-Christine Nadeau, Guillaume Duchateau, Mathieu Dumergue, Nikita Fedorov, Dominique Descamps, Stephane Petit, Ghita Geoffroy, and Patrick Martin

Doc ID: 320635 Received 26 Jan 2018; Accepted 09 Mar 2018; Posted 16 Mar 2018  View: PDF

Abstract: The dynamics of point defects formation and annihilation in potassium dihydrogen phosphate (KH2PO4 or KDP) crystals induced by multiple femtosecond laser pulses at 800 nm and 266 nm wavelengths is addressed. It is investigated through time-resolved photo-luminescence (PL) experiments in the [4.3eV; 6.3eV] spectral region for sample temperatures ranging from 20 K to 300 K. For both laser excitation wavelengths, a 5.1 eV energy PL band is found, which amplitude depends on the temperature, and exhibits a particular behavior around the Curie temperature (1 K). The low temperature PL band characteristics (energy, width, kinetic of PL decay) suggest that it is due to the radiative annihilation of self-trapped excitons (STEs). Above the Curie temperature, the PL band is centred around the same previous energy but exhibits a different width suggesting radiative annihilation of self-trapped holes next to the [HPO4]- group. During the laser irradiation at 1 kHz repetition rate of a low temperature sample, the PL signal at 5.1 eV decreases as a function of the irradiation time on a timescale going from a few seconds to a few minutes depending on both the laser wavelength and intensity. This behavior is attributed to the formation and annihilation of mobile hydrogen defects. A model based on rate equations provides the temporal evolution of the defects density, allowing us to reproduce and interpret the observed evolution of the PL signal. This model also provides timescales for the defects density evolution with respect to the laser wavelength and intensity.

The examination of the acousto-optic system characteristics controlling abilities by the feedback circuit parameters alteration

Sergey Mantsevich and Vladimir Balakshy

Doc ID: 313208 Received 10 Nov 2017; Accepted 08 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: The optoelectronic system containing collinear acousto-optic cell and positive electronic feedback was examined. The feedback signal is formed due to the optical heterodyning effect in unconventional regime of collinear acousto-optic diffraction. It is shown that the feedback circuit electrical parameters enable controlling the spectral characteristics of the acousto-optic cell, resulting in enhancing the maximal spectral resolution, spectral contrast of the system and the accuracy of optical wavelength determination. The examined optoelectronic device may be treated as the optical radiation spectrum analyzer, as the spectrum of electric signal in the feedback circuit is determined by the light spectrum on the system optical input. It is shown that the examined system may operate in the several modes – the regeneration mode and generation mode. The borders between the operation modes were examined both theoretically and experimentally.

Scaling for ultrashort pulse amplification in plasma via Backward Raman Amplification scheme operating in short wavelength regime

Sanjay Mishra and A. Andreev

Doc ID: 309075 Received 16 Oct 2017; Accepted 08 Mar 2018; Posted 08 Mar 2018  View: PDF

Abstract: The applicability of extreme ultraviolet (XUV) and soft X-ray radiation sources in resonant Backward Raman amplification (BRA) scheme in amplifying the weak ultrashort sub femtosecond (fs) pulses has been examined. Utilizing the slowly varying envelop approximation (svea) based analytical expressions for the resonant three wave interaction alongwith viable physics constraint, a parameter space configuring the laser/ plasma features required to achieve significant pulse amplification and compression, has been derived. A specific parametric regime for resonant BRA operation in short wavelength regime has been identified and validated using particle in cell (PIC) simulation results. The outcome predicts that the resonant BRA scheme may efficiently be applied to amplify the weak pulses for the pump radiation operating within the XUV regime; the effect may be optimized via efficient tuning of the plasma density, pump pulse intensity and wavelength of the interacting waves. As an illustration, resonant BRA scheme in reference to DESY FLASH XUV laser source has been conceptualized and a competent set of laser/plasma parameters in achieving significant amplification is configured; the limitations and plausible rectification for a practical execution of the resonant BRA has also been discussed.

Generation of an isolated attosecond pulse via current modulation induced by a chirped laser pulse inX-ray free electron laser

Sandeep Kumar, Jaeyu Lee, Minsup Hur, and Moses Chung

Doc ID: 307943 Received 26 Sep 2017; Accepted 08 Mar 2018; Posted 13 Mar 2018  View: PDF

Abstract: Aiming for the future upgrade of hard X-ray beamline at the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), we first analyze the scheme recently proposed for the attosecond-terawatt (TW) X-ray pulse [T. Tanaka, Phys. Rev. Lett. 110, 084801 (2013)]. An X-ray pulse with 32 as full-width half maximum (FWHM) pulse duration and ~ 4 TW in power is shown in simulations using the PAL-XFEL parameters. Furthermore to remove neighboring radiation pulses and to generate an isolated attosecond-TW X-ray pulse, the role of optical laser frequency chirp is examined on the electron beam current modulation as well as on the X-ray pulse generation in the undulator. Our simulations show an isolated X-ray pulse with 42 as FWHM pulse duration and ~ 3.5 TW in power for the optimal frequency-chirp of a 400 nm optical laser. Recently, in a simpler method [T. Tanaka et al., J. Synchrotron Rad. , 1273 (2016)] and [Z. Wang et al., Phys. Rev. ST Accel. Beams 20, 040701 (2017)], using a frequency-chirped optical laser and the electron beam delays inbetween undulator sections, it has been reported that an isolated attosecond-TW X-ray pulse can be obtained at the undulator end. For the optimal chirp in this simple method, we show 50 as FWHM pulse duration and ~3 TW in power with 7.5×10^10 photons per pulse at 0.1 nm radiation wavelength. Generation of such inherently synchronized, powerful single attosecond X-ray pulse at PAL-XFEL will be advantageous to the pump-probe experiment in the study of ultrafast dynamics.

Ultrashort laser pulse driven currents in conductors: physical mechanisms and time scales

Peter Földi, Lóránt Szabó, and Magashegyi István

Doc ID: 312424 Received 01 Nov 2017; Accepted 08 Mar 2018; Posted 13 Mar 2018  View: PDF

Abstract: The response of conduction band electrons to a local, pulse-like external excitation is investigated. The charge density wave packets that emerge as a consequence of the excitation leave the interaction region with a speed close to the initial state's band velocity, but there are also oscillations with essentially the same frequency as that of the laser field. As a good estimation, the excitation can also be considered as a localized, time-dependent ponderomotive potential, leading to slowly varying current oscillations. The role of all these effects are investigated for different electron energies, carrier frequencies and sizes of the interaction area.

Self-starting 12.7 fs pulse generation from harmonic mode-locked Ti:sapphire laser pumped by a femtosecond Yb:KGW laser

Zhaohua Wang, Hao Meng, Jiang Jiang, wenlong tian, SHAOBO FANG, and Zhiyi Wei

Doc ID: 320263 Received 22 Jan 2018; Accepted 06 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: A self-starting femtosecond harmonic mode-locked Ti:sapphire laser is demonstrated, pumped by a 75.5 MHz frequency-doubled mode-locked Yb:KGW oscillator. The maximum average output power is 256 mW at the central wavelength of 811 nm with 3.6 W pump power. The pulses duration as short as 12.7 fs are obtained by using a 3% output coupler. The pulse repetition rate is 151 MHz, which is successfully locked to the twice of repetition rate of the pump laser.

Dual-band superposition induced broadband terahertz linear-to-circular polarization converter

XiaoFei Zang, Suji Liu, Hanhong Gong, YAJUN Wang, and Yiming Zhu

Doc ID: 315494 Received 11 Dec 2017; Accepted 06 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: A reflective broadband terahertz (THz) linear-to-circular (LTC) polarization converter is designed and experimentally demonstrated based on single-layer ultrathin metasurface. Two size-different rectangular ultrathin metasurface micro-structures are proposed to realize such broadband THz LTC polarization converter with bandwidth ranging from 0.832 to 1.036 THz. The phase delay between two orthogonal resonance modes is -90^0±5^0. These qualities are realized mainly by combining two separated LTC polarization conversion frequencies and benefit of the coupling between two size-different rectangles. The calculated results indicate that the bandwidth of the LTC polarization converter is controlled via dimensions of size-different rectangles. This kind of ultrathin broadband THz polarization converter can be widely applied into wireless communication, imaging, detection, and widen the path to design novel functional terahertz devices.

Carrier-envelope phase effects in graphene

Catherine Lefebvre, Denis Gagnon, François Fillion-Gourdeau, and Steve MacLean

Doc ID: 309178 Received 16 Oct 2017; Accepted 06 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: We numerically study the interaction of a terahertz pulse with monolayer graphene. We observe that the electron momentum density is affected by the carrier-envelope phase (CEP) of the single to few-cycle terahertz laser pulse that induces the electron dynamics. In particular, we see strong asymmetric electron momentum distributions for non-zero values of the CEP. We explain the origin of the asymmetry within the adiabatic-impulse model by finding conditions to reach minimal adiabatic gap between the valence band and the conduction band. We discuss how these conditions and the interference pattern, emanating from successive non-adiabatic transitions at this minimal gap, affect the electron momentum density and how they are modified by the CEP. This opens the door to control fundamental time-dependent electron dynamics in the tunneling regime in Dirac materials. Also, this suggests a way to measure the CEP of a terahertz laser pulse when it interacts with condensed matter systems.

Evolution dynamics of vortex quasi-Airy beams

Yunlong Wu, Nie Jinsong, and Li Shao

Doc ID: 322819 Received 08 Feb 2018; Accepted 05 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: impact of spiral phase on the propagation dynamics of quasi-Airy beams depends on the included angles of the beams, which will result in different propagation directions of the two separated trajectories. The first and second moment radius along x-y axes are utilized to study the beam spreading due to the non-symmetry of the quasi-Airy beams. It is found that, unlike the common Airy beams, the variation of first moment is not proportional to the topological charge and it will present some anomalous regularities when the quasi-Airy beams appear quite differently from the common ones. In addition, the second moment difference between quasi-Airy beams with different topological charges is quite small unless the quasi-Airy beams are close to the common ones. Furthermore, the quasi-Airy beams with a spiral phase are generated experimentally by loading the combined phase patterns into a spatial light modulator directly and their propagation dynamics are demonstrated in detail. The experimental results are coincident with the numerical results. Our results will help to provide a broad application in trapping atom and optical tweezers.

Broadband gain induced Raman comb formation in a silica microresonator

Ryo Suzuki, Akihiro Kubota, Atsuhiro Hori, Shun Fujii, and Takasumi Tanabe

Doc ID: 315655 Received 14 Dec 2017; Accepted 04 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: A high-Q silica whispering-gallery mode microresonator is an attractive platform on which to demonstrate a broad and phase-locked Raman comb in various wavelength regimes. Raman combs can be used for applications such as compact pulse laser sources, sensors, optical clocks, and coherence tomography. However, the formation dynamics of a Raman comb has not been well exploited. Here we study the dynamics of the Raman comb formation in silica rod microresonators, which have cavity free spectral ranges in microwave rates. We generated a Raman comb with a smooth spectral envelope and also observed the transition between two Raman combs located at different center wavelengths. The transition behavior was obtained when we changed the pump detuning and the coupling strength between the microresonator and fiber. We also explain these phenomena by using a simple model based on coupled mode equations.

Effects of loss on the phase sensitivity with parity detection in an SU(1,1) interferometer

Dong Li, Chunhua Yuan, Yao Yao, Wei Jiang, Mo Li, and Weiping Zhang

Doc ID: 309106 Received 16 Oct 2017; Accepted 04 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: We theoretically study the effects of loss on the phase sensitivity of an SU(1,1) interferometer with parity detection. We show that although the sensitivity of phase estimation decreases in the presence of loss, it can still beat the shot-noise limit with small loss. Compared with homodyne detection, parity detection has a slight better optimal phase sensitivity in the absence of loss, but has a worse opitmal phase sensitivity with a significant amount of loss.

Simultaneous few-cycle pulse generation of the depleted pump and signal from an optical parametric amplifier

Derrek Wilson, Xiaoming Ren, Stefan Zigo, Francois Legare, and Carlos Trallero-Herrero

Doc ID: 304588 Received 30 Oct 2017; Accepted 04 Mar 2018; Posted 05 Mar 2018  View: PDF

Abstract: We generate few-cycle laser pulses from both the depleted pump and signal of an optical parametric amplifier using self phase modulation in a single hollow core fiber. Despite the depleted pump’s poor spatial quality entering the fiber, it produces a field with less than 2.5 cycles. Moreover, we can simultaneously (same fiber) generate a 4 cycle pulses from the signal. The coherent combination of both pulses allows for bandwidth spanning from 500 nm to 1500 nm. The geometry allows for minimal path differences of the two fields, paving a route for generating multi-octave, synthesized light transients centered in the near-infrared.

BER Calculation for Single-channel Silicon Optical Interconnects Utilizing RZ Pulsed Signals

Nicolae Panoiu and Jie You

Doc ID: 318987 Received 03 Jan 2018; Accepted 03 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: We introduce an accurate and efficient approach to compute the transmission bit-error ratio (BER) of single-channel silicon photonic interconnects when the optical signal consists of arbitrarily shaped optical pulses. The silicon photonic systems investigated in this study contain an optical transmitter, a silicon optical interconnect, which can be either a strip single-mode silicon photonic waveguide (Si-PhW) or a silicon photonic crystal (PhC) waveguide (Si-PhCW), and a direct-detection receiver. The input signal consists of a superposition of a train of Gaussian pulses and white noise, its propagation in the silicon waveguide being described by a rigorous theoretical model based on a modified nonlinear Schrodinger equation, which captures all relevant linear and nonlinear optical effects. The statistical properties of the output signal and the corresponding BER were determined using the Fourier series Karhunen-Loeve expansion method. Our analysis reveals that in the case of Si-PhWs the pulse width is the parameter that most strongly influences the BER, whereas for Si-PhCWs the main factor affecting BER is the pulse group-velocity. Finally, we show that similar values of BER are achieved in Si-PhCWs with length of about two orders of magnitude smaller than that of Si-PhWs, a further reduction of the silicon interconnect footprint being possible if the Si-PhCW is operated in the slow-light regime.

Shaping the light with microchannel silicon

Gennady Medvedkin

Doc ID: 318991 Received 03 Jan 2018; Accepted 03 Mar 2018; Posted 06 Mar 2018  View: PDF

Abstract: Among exotic forms of silicon, microchannel silicon stands out its double crystal structure with an additional mesoscopic crystal lattice and unusual optical properties in contrast to bulk crystals and thin-films. A number of non-trivial effects have been observed in visible light, such as 2D diffraction, 2D spectral dispersion, high optical transmission, optical anisotropy, and conoscopic figures. Experiment, calculation and 3D simulation show the microchannel silicon material becomes optically transparent with T > 80%, optically uniaxial with an anisotropic ratio of 5∙105, full spectrum dispersive, and its weight is reduced five times as compared to conventional crystalline silicon.

Quantum interferometry with superpositions of asymmetric two-modeFock states

Shuai Wang, YAO-TING WANG, Liangjun Zhai, and Lijian Zhang

Doc ID: 314997 Received 05 Dec 2017; Accepted 02 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: We derive a general expression of the expectation value of the parity operator in the quantum interferometry with superpositions of asymmetrictwo-mode Fock states. Our results show that although the optimal phaseuncertainty is obtained for twin Fock states ($m=n$), the difference betweenthe twin Fock states and the asymmetric two-mode Fock states is very smallfor large $m$ and $n$. As applications, we consider the interferometer inputstates with a Fock state and a coherent state, as well as a Fock state and asqueezed vacuum state. We find that, for such superpositions of asymmetrictwo-mode Fock states, both phase resolution and phase uncertainty are almost identical to each other for very small phase shift. When a Fock state with large photon number enters one port of the interferometer, for suchsuperpositions of asymmetrical two-mode Fock states, both phase ncertaintyand phase resolution are very close to those obtained with twin Fock statesinput.

Surface-Plasma Attosource beamlines at ELI-ALPS

Sudipta Mondal, Mojtaba Shirozhan, Naveed Ahmed, Maimouna Bocoum, Frederik Boehle, Aline Vernier, Stefan Haessler, Rodrigo Lopez-Martens, François Sylla, Cedric Sire, Fabien Quéré, Kwinten Nelissen, Katalin Varjú, Subhendu KAHALY, and Dimitris Charalambidis

Doc ID: 312639 Received 03 Nov 2017; Accepted 01 Mar 2018; Posted 14 Mar 2018  View: PDF

Abstract: ELI-ALPS, one of the three pillars of Extreme Light Infrastructure project (ELI), will be in a unique position to offer dedicated experimental platforms for ultrashort time-resolved investigations of strongly excited dynamical systems. The state of the art surface-plasma attosource (SPA) beamlines at ELI-ALPS are being designed and developed to enable new directions in plasma based attoscience research. TheSPA beamlines will be driven by ultrashort high peak power high repetition rate lasers based on latest technology and are aimed to operate in a previously inaccessible regime of surface high-order harmonics generation. This endeavour involves R & D challenges and careful considerations. Here we discuss the physics of plasma attosources and their characteristics under such extreme conditions and the beamline functionalities that would allow for achieving these. Finally we delineate the initial research possibilities with these sophisticated instruments.

Enhancement of high harmonic generation by multiple reflection of ultrashort pulses

Zsolt Lécz and Alexander Andreev

Doc ID: 309949 Received 24 Oct 2017; Accepted 01 Mar 2018; Posted 05 Mar 2018  View: PDF

Abstract: In the regime of moderate intensity laser-solid interactions the shortest wavelength is defined by the electron density in the target, which allows us to generate harmonic numbers up to ~30, corresponding to about 30 nm wavelength. It has been shown that by combining the laser fundamental with its low-order harmonics the significant enhancement of high harmonic intensity can be achieved, even above this frequency cut-off. Since the laser pulse reflected from a plasma inherently contains the low order harmonics, a second reflection from a fresh plasma surface leads to the increase of spectral intensity. In this work we have made an extensive study of multiple reflections of a short pulse between two solid density plasma walls at oblique incidence, with the help of 1D and 2D Particle-in-Cell simulations. A loosely focused pulse is considered which can propagate between two flat foils over consecutive reflections without significant loss of intensity. It is shown that for optimal parameters the intensity from 10th to 30th harmonics can be amplified by three orders of magnitudes.

Landé gJ values in 20Ne: New measurements of gJ(2p8), gJ(2p9), and gJ(2p10) by saturation spectroscopy

John Brandenberger, Willa Dworschack, and Theodore Kortenhof

Doc ID: 314656 Received 06 Dec 2017; Accepted 01 Mar 2018; Posted 01 Mar 2018  View: PDF

Abstract: Saturated absorption laser spectroscopy has been used to measure ratios of Landé gJ factors gJ(2p8)/gJ(1s5), gJ(2p9)/gJ(1s5), and gJ(2p10)/gJ(1s5) in 20Ne. Then by invoking an existing 5 ppm experimental value for gJ(1s5), we arrive at new experimental values gJ(2p8) = 1.1364(4), gJ(2p9) = 1.3332(4) and gJ(2p10) = 1.9908(3), whose 300 and 150 ppm uncertainties represent x2 and x5 improvements over previous measurements.

Disordered nanophotonic surfaces for enhanced light collection in semiconductor solar cells

Chelsea Carlson and Stephen Hughes

Doc ID: 309505 Received 19 Oct 2017; Accepted 28 Feb 2018; Posted 06 Mar 2018  View: PDF

Abstract: We study photonic crystal wire and hole (slab) geometries as a scattering entrance layer to potentially enhance the absorption in a thin-film photovoltaic solar cell, examining the role of positional and radial disorder in total photon absorption. One commonly accepted gold standard for scattering enhanced absorption in solar films is given by the Lambertian limit, which results in an optical path length enhancement of 4n² , where n is the refractive index. However, this limit is often an upper limit and hard to realize in practise. We first explore the limitations and practical implementation of this ideal enhancement using finite-difference time-domain (FDTD) simulations of realistic rough surfaces. A practical rough film, characterized by the RMS height (σRMS ) and correlation length (Lx,y ) of the random peaks, is first optimized for different substrate thicknesses over an optical range of 400-1100 nm, weighted by the solar irradiance spectrum. The optimized surface reflectsthe practical theoretical limit for Lambertian slab thicknesses above 500 nm and wavelengths in the near-UV, but performed worse in the near-IR (∼ 80%). The physical total height of the optimal rough surfaces are on the order of 2 μm, which contradicts the usual assumption that absorption losses within the rough film are negligible. To compare and contrast with a Lambertian “roughsurface,” we introduce positional and radial disorder within optimized photonic crystal wire and slab holes, for a fixed height of 1 μm with reflective Ag substrates, considering both GaAs and Si semiconductors. We find that the optimized GaAs nanowires gave the largest total short-circuit current (J sc ) of 30 mA/cm² . Relative to the unpatterned slabs of the same height, the greatestPC enhancements in absorption were seen for c-Si nanoholes and GaAs nanowires (1.65 and 1.33, respectively). The inclusion of disorder increases the absorption enhancement in all structures by 4-15%, except GaAs nanoholes, which remained within 1% of the ordered structure. Using an analysisof the local density of photon states, which is strongly dependent on the complex dielectric constant of the semiconductor materials, we show that, due to the higher inherent resonance broadening, the useful effects of disorder induced resonance broadening is minimized in GaAs, compared to c-Si.Thus, silicon shows the greatest benefit to the disorder induced-scattering while GaAs shows little or no enhancement using photonic crystal entrance layers.

Waveguide bends by optical surface transformations and optic-null media

Sun Fei and Sailing He

Doc ID: 319664 Received 12 Jan 2018; Accepted 28 Feb 2018; Posted 28 Feb 2018  View: PDF

Abstract: We propose a general method to design waveguide bends with arbitrary bending angles by a graphical method, which is very simple and convenient. The proposed method is based on a new theoretical branch from transformation optics, which is referred as to optic surface transformation. All waveguide bends designed by the method proposed in this study only need one homogeneous material, i.e. an optic-null medium, to be realized (even if the bending angles are different for various cases). After some reductions, we find that the optic-null media here can be approximately realized by anisotropic, zero refractive index materials.

Si-Core Photonic Crystal Fiber Transverse Electric Pass Polarizer

Jideofor Odoeze, Mohamed Hameed, Hossam Shalaby, and Salah Obayya

Doc ID: 319969 Received 18 Jan 2018; Accepted 27 Feb 2018; Posted 28 Feb 2018  View: PDF

Abstract: Photonic crystal fibers (PCFs) have been extensively used in literature for designing polarization handling devices.Further, the Si material has advantages in terms of low loss transmission with high refractive index. In this paper, a novel design of transverse electric (TE) pass polarizer based on Si-core photonic crystal fiber (SC-PCF) is reported and studied using full vectorial finite element method. The suggested PCF has a SiO2 cladding background and is selectively filled with gold nanorods. Further, an elliptical Si-core is used to increase the birefringence between the two polarizing modes. Therefore, the surface plasmon modes around the gold nanorods are highly coupled with the quasi-Transverse Magnetic (TM) core modes while no coupling occurs with the quasi-TE core mode. Consequently, high and low confinement losses are achieved for the quasi TM and quasi TE core modes, respectively. Accordingly, a TE-pass polarizer is realized with an insertion loss of−0.000108 dB. Additionally, a good extinction ratio of −13.18 dB is obtained at a short device length of 29 µm.

Time resolved and spectrally resolved ionization with a single ultrashort XUV- IR beamline

Vincent Loriot, ludovic quintard, Gabriel karras, alexandre Marciniak, Fabrice Catoire, Marius Hervé, isabelle compagnon, Gina Renois-predelus, Baptiste Schindler, Bruno Concina, Gulabi Celep, Richard Brédy, Christian Bordas, Frank Lepine, and Eric Constant

Doc ID: 312635 Received 03 Nov 2017; Accepted 27 Feb 2018; Posted 28 Feb 2018  View: PDF

Abstract: We present an upgrade of a time resolved attosecond XUV-IR setup designed to perform both time resolved and spectrally resolved studies of a target under nearly identical experimental conditions. A flat XUV grating located on the path of the attosecond pulse train obtained via HHG in gases is used in the zeroth order of diffraction to follow attosecond dynamics or in the first order of diffraction to study the target response after excitation with a single harmonic. Electron momentum measurement is performed with a Velocity Map Imaging spectrometer and the 10 W femtosecond laser system operating at 5kHz provides an XUV photon flux compatible with rapid acquisition in both the monochromatic and broadband configuration. The change of experimental configuration between broadband and monochromatic sources is rapid and performed in situ. We present here the experimental implementation applied to Krypton atoms and detail the capabilities and limits of this approach when a flat XUV grating with constant groove density is used.

Quantum tunneling switch in an interacting many-body bosonic system

Sheng-Chang Li

Doc ID: 315657 Received 14 Dec 2017; Accepted 27 Feb 2018; Posted 28 Feb 2018  View: PDF

Abstract: I adopt a two-mode bosonic model with both strong atom-atom interaction and a periodic driven field to investigate the bias-modulated tunneling dynamics. I show that the quantum tunneling between two bosonic modes can be efficiently switched on/off when one continuously varies the amplitude of thedriven field with an intermediate frequency. I explore the role of the atom-atom interaction on the switch effect as well. For the strong interaction case, in contrast to the unmodulated situation, there exists many windows in the atomic interaction domain for switching on/off the quantum tunneling. This result suggests a potential way to accurately control the quantum tunneling or coherent coupling of ultracold atoms in strong interaction and self-trapping regime.

The generation of a ring-shaped focusing spot with precisely controllable position and diameter

jiannong chen, Chenglong Zhao, Dawei Zhang, Bo Dai, Linwei Zhu, and Qinfeng Xu

Doc ID: 318818 Received 02 Jan 2018; Accepted 26 Feb 2018; Posted 06 Mar 2018  View: PDF

Abstract: We demonstrate that a dynamical manipulation of a yeast cell in an arbitrary route can be realized using a circularly symmetrical ring-shaped focusing spot with a controllable center and an adjustable diameter in the focal plane of a high numerical-aperture objective lens. The ring-shaped spot is composed of multiple spots located on the circumference of the ring with small enough diameter in an equally spaced manner between adjacent spots. The multiple spots is generated by phase modulation the principle of which is based on the phase shift theorem of Fourier transform.

Influence of Optical Feedback Strength and Semiconductor Laser Coherence on Chaos Communication

Ban Al Bayati, Ahmad Khedher, and Kais Al Naimee

Doc ID: 313866 Received 20 Nov 2017; Accepted 25 Feb 2018; Posted 26 Feb 2018  View: PDF

Abstract: The existence of high chaotic spiking in the dynamics of semiconductor lasers with an AC-coupled optical feedback is investigated experimentally. After chaos signal generation, the effect of attenuation feedback strength as a control parameter is studied, and the time evolution of photon density is analyzed. The chaotic instability is tested; our results exhibit monostability in dynamics. By applying different frequencies to observe the hidden regions, the chaotic dynamic results are indicated as a good candidate to hide information for satisfying the resonance phenomenon, to evaluate the secure optical communication.

Sub-kHz excitation lasers for Quantum Information Processing with Rydberg atoms

Jonathan Pritchard, Rémy Legaie, and Craig Picken

Doc ID: 318054 Received 21 Dec 2017; Accepted 25 Feb 2018; Posted 26 Feb 2018  View: PDF

Abstract: Quantum information processing using atomic qubits requires narrow linewidth lasers with long-term stability for high fidelity gate operations. In this paper, we report on the construction and characterization of three continuous-wave (CW) narrow linewidth lasers stabilized simultaneously to an ultra-high finesse Fabry-Perot cavity made of ultra-low expansion (ULE) glass, with a tunable offset-lock frequency. One laser operates at 852~nm while the two locked lasers at 1018~nm are frequency doubled to 509~nm for excitation of $^{133}$Cs atoms to Rydberg states. The optical beatnote at 509~nm is measured to be 260(5)~Hz. We present the calibration of ULE cavity frequency with respect to atomic resonances using electromagnetically induced transparency (EIT) for high-resolution spectroscopy on a cold atom cloud. The long-term stability is determined from repeated spectra over a period of 20 days yielding a linear frequency drift of $\sim1$~Hz/s.

Light diffusion in a turbid cylinder with oblique incident pencil beam

Shu Zhang, Wei Wei, and Zuojun Tan

Doc ID: 309424 Received 18 Oct 2017; Accepted 23 Feb 2018; Posted 23 Feb 2018  View: PDF

Abstract: Here we studied the light transport initiated by oblique illumination of a turbid cylinder on its top or barrel with a pencil beam. Solutions were derived for the steady-state, frequency, and time domains. Time- and spatially resolved reflectance results with different incident angles agreed well with those of Monte Carlo simulations. A method to determine optical properties using the time and spatially resolved reflectance results along the z direction was proposed for the light incident on the cylinder barrel. Analytical solutions can improve analysis of turbid cylindrical media with incident illumination and effective optical properties reconstruction.

The passive decoy-state quantum key distribution with SARG04protocol

Kang Liu, Jie Wei, chunmei Zhang, and Qin Wang

Doc ID: 315278 Received 08 Dec 2017; Accepted 19 Feb 2018; Posted 06 Mar 2018  View: PDF

Abstract: We present a new scheme on realizing the passive decoy-state quantum key distribution with SARG04 protocol. It is based on the parametric-down conversion sources, and only one-intensity pumping light is used. By applying splitting-local-modes detections at Alices side, the legitimate users can get four different kinds of counting events at Bobs side due to the intrinsic correlations between photon pairs from parametric-down conversion processes. As a result, quite precise estimations for the single- or multi-photon-pulse contributions could be obtained, which enables better performance of the key generation rate and the transmission distance compared with other existing SARG04 proposals, e.g., the four-intensity decoy-state method using either parametric-down conversion sources orweak coherent sources.

Rogue waves under influence of Raman delay

Adrian Ankiewicz, Mahyar Bokaeeyan, and Nail Akhmediev

Doc ID: 319307 Received 08 Jan 2018; Accepted 18 Feb 2018; Posted 23 Feb 2018  View: PDF

Abstract: Rogue waves can appear in {optical fibers and other optical systems, as well as in natural events like water waves. }Their mathematical description is based on partial differential equations that have solutions that are localized both in time and space.One example is the Peregrine solution of the nonlinear Schr\"odinger equation (NLSE). When higher-orderterms in the equation are involved, the solution becomes distorted, but its main features remain localized in space and time. Although exact solutions are not obtained in all cases,approximations which describe the solutions with reasonable accuracy do exist. Here, we consider approximate rogue wave solutions of the NLSE with an optically-relevant Raman delay term.

Entangled multi-mode spin coherent states of trapped ions

Yusef Maleki and Alireza Maleki

Doc ID: 315874 Received 18 Dec 2017; Accepted 13 Feb 2018; Posted 16 Feb 2018  View: PDF

Abstract: Multi-mode macroscopic states consisting of asuperposition of spin coherent states that are generated in a trapped ion system are introduced. The role of various parameters that control the entanglement of the system are exposed and their effects are quantified.In particular, it is shown that the generated states exhibit different entanglement characteristics for odd and even $2nj$, where jis the spin of each mode and $n$ is the number of modes.

Ultra-stable collinear delay control setup forattosecond IR-XUV pump-probe experiment

Amelle Zaïr, Eric MEVEL, Eric Cormier, and Eric Constant

Doc ID: 312636 Received 03 Nov 2017; Accepted 05 Feb 2018; Posted 14 Mar 2018  View: PDF

Abstract: We present a robust design for performing time resolved measurementwith IR femtosecond laser pulses and attosecond XUV pulses. The setup contains no reflective elements and provides a delay control down to 5 attoseconds without any active stabilization.Temporal characterization of an attosecond XUV pulse train generated in Krypton is presented here to demonstrate the validity of our approach.

Asymmetric optical transmission through silver film with a hyperbolic air hole

Weilong She, xin li, and Wanguo Liu

Doc ID: 308854 Received 27 Oct 2017; Accepted 25 Jan 2018; Posted 30 Jan 2018  View: PDF

Abstract: Asymmetric optical transmission is one of the most important functionality in modern optical communication system. However, it has been impeded due to the low transmission ratio of forward transmittance to backward one. Here, we propose asymmetric optical transmission through a silver film with a hyperbolic air hole (HAH), of which the ratio is as high as 24.5 at a proper wavelength. The mechanism is the fact that the steep inner wall of the silver film HAH can inhibit guided mode reflection. This kind of silver film HAH is expected to have the potential served as asymmetric optical transmission device.

Investigating force distribution inside the spoof surface plasmon polariton waveguide

Mahdi Aghadjani, Mikhail Erementchouk, and Pinaki Mazumder

Doc ID: 300742 Received 15 Aug 2017; Accepted 26 Nov 2017; Posted 01 Mar 2018  View: PDF

Abstract: The Maxwell stress tensor of the field inside a spoof surface plasmon polariton (SSPP) waveguide and the electromagnetic force distribution acting on a dielectric particle are investigated. We show that for particles made of material with the dielectric function slightly different from that of the medium filling the waveguide, the force distribution is fully described by the SSPP field in the absence of the particle. The spatial profile of the field depends on the relation between the operating frequency and the SSPP resonance frequency. This introduces a switching effect, when the direction of the force along the waveguide axis changes its direction (from toward the grooves to away from them) when the frequency varies. We propose a pumping mechanism based on force acting on a small particle inside the SSPP waveguide

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