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All-Optical Tunable Delay Line Based on Nonlinearities in Chalcogenide Microfiber Coil Resonator

Amir Kowsari, Vahid Ahmadi, ghafar darvish, and Mohammad Moravvej-Farshi

Doc ID: 290790 Received 20 Mar 2017; Accepted 23 Apr 2017; Posted 24 Apr 2017  View: PDF

Abstract: We propose an all-optical tunable delay line based on nonlinear effects in a two-turn chalcogenide microfiber coil resonator (MCR). Continuous rotation of light due to coupling between the two uniform MCR turns at the resonance induces a time delay. Using numerical simulation, we show the possibility of designing a continuously tunable all-optical and real-time delay line, taking advantage of the high Kerr nonlinear effect in a chalcogenide glass based MCR. The threshold power for making the Kerr nonlinearity in the chalcogenide sulfide glass (Ge20Ga5Sb10S65 also known as 2S2G) MCR is less than 0.1W. By selecting an appropriate pump power, one can adjust the time delay in the proposed MCR delay line as desired. Results of numerical simulations show that the time delay in an appropriately designed two-turn MCR can be tuned in the range of 24 to 147 ps with a bandwidth of ~4.1 GHz. Pulse broadening and distortion related to GVD and SPM effect of the proposed MCDL are also studied.

Artificial gauge magnetic and electric fields for free two-level atoms interacting with optical Ferris wheel light fields

Vassilis Lembessis, Ahlam Alqarni, Suad Alshamari, Abubaker Siddig, and Omar Aldossary

Doc ID: 285512 Received 24 Jan 2017; Accepted 21 Apr 2017; Posted 21 Apr 2017  View: PDF

Abstract: We consider the creation of artificial gauge magnetic and electric fields created when a two-level atom interacts with an optical Ferris wheel light field.These fields have the spatial structure of the optical Ferris wheel field intensity profile. It is shown, for first time, that when this optical field pattern is made to rotate in space then we have the creation of artificial electromagnetic fields which propagate in curved paths. The properties as well the limitations of these artificial electromagnetic fields are investigated and discussed.

Anomalous interactions of nonparaxial accelerating beams in nonlocal nonlinear media

Yunlong Wu, Li Shao, and Nie Jinsong

Doc ID: 280609 Received 10 Nov 2016; Accepted 20 Apr 2017; Posted 21 Apr 2017  View: PDF

Abstract: We numerically investigate the anomalous interaction dynamics of nonparaxial accelerating beams in nonlocal nonlinear media. We find that stationary breathing bound states of spatial solitons can be formed with the help of nonlocality in the in-phase case. But it would be difficult to generate the bound states when the input amplitudes between the separated beams are different. Interestingly, the spatial solitons formed in the interactions with different amplitudes can propagate along the new sinusoidal path and the path can be modulated flexibly by altering the degree of nonlocality. Furthermore, it is found that new non-overlapping bound states can be generated from anomalous interactions in the out-of-phase case. In addition, the parameter of longitudinal vortex of order can have different impacts on the interaction dynamics in the in-phase case and out-of-phase, respectively.

Radiation Pressure on a Diffractive Sailcraft

Grover Swartzlander

Doc ID: 285006 Received 17 Jan 2017; Accepted 19 Apr 2017; Posted 20 Apr 2017  View: PDF

Abstract: Advanced diffractive films may afford advantages over passive reflective surfaces for a variety space missions that use solar or laser in-space propulsion. Three cases are compared: Sun-facing diffractive sails, Littrow diffraction configurations, and conventional reflective sails. A simple Earth-to-Mars orbit transfer at a constant attitude with respect to the sun-line finds no penalty for transparent diffractive sails. Advantages of the latter approach include actively controlled metasails and the reuse of photons.

Facet Dependent Electric Field Induced Second Harmonic Generation in Silicon and Zincblende

Adalberto Alejo-Molina, Hendradi Hardhienata, Pedro Marquez Aguilar, and Kurt Hingerl

Doc ID: 287545 Received 06 Mar 2017; Accepted 18 Apr 2017; Posted 20 Apr 2017  View: PDF

Abstract: We discuss electric field induced second harmonic (EFISH) generation for silicon and zincblende facets (001), (011) and (111), employing the full fourth-rank tensor representation of the third order susceptibility and relating directly this 81 tensor elements with the contracted or Voigt matrix representation. Using group theory we show that the number of independent elements is only two, however, at different facets different linear combinations thereof appear. Also, specific expressions for the resulting s- and p- polarized second harmonic polarization are given for incident s- and p- polarizations, for the first time explaining the facet and angle of incidence dependence of EFISH. Finally, a classical oscillator model is used to explain the response of the electrons and the material combined with a direct physical interpretation of the breaking of the symmetry and thus the deformation of the electronic charge density along the bonds. Through this model we propose a connection between the strength parameter b for third harmonic generation and the second harmonic signal originated by EFISH mechanism.

Tunable Resonant Goos-Hänchen and Imbert-Fedorov Shifts in Total Reflection of Terahertz Beams from Graphene Plasmonic Metasurfaces

ali farmani, Mehdi Miri, and Mohammad Hossein Sheikhi

Doc ID: 290432 Received 10 Mar 2017; Accepted 18 Apr 2017; Posted 20 Apr 2017  View: PDF

Abstract: Highly-tunable enhanced lateral displacements in the center of gravity of totally reflected light beams from a graphene plasmonic metasurface is investigated. Multiple reflections of the incident beam, and the resonant coupling between the incident beam and the surface modes of the graphene metasurface in each reflection, are employed to enhance the Goos-Hänchen and Imbert-Fedorov shifts in the proposed structure. It is shown that spatial Goos-Hänchen and Imbert-Fedorov shifts as high as 1089 λ0 and -44.66 λ0 (λ0: incident wavelength) are achievable in the proposed structure. The effect of different parameters including the incident beam waist, temperature, the scattering time and the chemical potential of the graphene on the shift values are then studied. Because of the strong light confinement in the surface modes of the graphene metasurface, the dispersion properties of these modes and, therefore, the coupling strength between the incident beam and these modes, are highly sensitive to the parameters of the reflecting structure and the incident beam itself. The high sensitivity of the coupling strength between the incident beam and the surface modes is then exploited to tune the shift values. It is shown that by introducing the small change of; ∆µC = 0.02 eV, in the chemical potential of the graphene, the spatial Goos-Hänchen and Imbert-Fedorov shift variations of 855 λ0 and -31 λ0 can be achieved, respectively. The wide range of the lateral shift variations along with the relatively small required actuating power recommend the application of the proposed structure in the realization of optical devices such as temperature sensors, and switches.

Coherent control of a single nitrogen-vacancy center spin in optically levitated nanodiamond

Robert Pettit, Levi Neukirch, and Nickolas Vamivakas

Doc ID: 285191 Received 26 Jan 2017; Accepted 18 Apr 2017; Posted 21 Apr 2017  View: PDF

Abstract: We report the first observation of electron spin transients in single negatively charged nitrogen-vacancy (NV−) centers, contained within optically trapped nanodiamonds, in both atmospheric pressure and low vacuum. It is shown that after an initial exposure to low vacuum, the trapped nanodiamonds remain at temperatures near room temperature even in low vacuum. Furthermore, the transverse coherence time of the NV−center spin, measured to be T2 = 101.4 ns, is robust over the range of trapping powers considered in this study.

In-situ tuning of whispering gallery modes of levitated silica microspheres

Yosuke Minowa, yuusuke toyota, and Masaaki Ashida

Doc ID: 283958 Received 03 Jan 2017; Accepted 18 Apr 2017; Posted 20 Apr 2017  View: PDF

Abstract: We demonstrated the tuning of whispering gallery modes (WGMs) of a silica microsphere during optical levitation through the annealing process. We determined the annealing temperature from the power balance between the CO₂ laser light heating and several cooling processes. Cooling caused by heat conduction through the surrounding air molecules is the dominant process. We achieved a blue shift of the WGMs as large as 1 \%, which was observed in the white-light scattering spectrum from the levitated microsphere.

High-precision three-dimensional atom localization in a microwave-driven atomic system

Yu-shan Mao and Jian-chun Wu

Doc ID: 286638 Received 14 Feb 2017; Accepted 12 Apr 2017; Posted 12 Apr 2017  View: PDF

Abstract: We demonstrate the behavior of three-dimensional (3D) atom localization in a four-level $Y$-type atomic system driven by a microwave field. The position information of the atom can be obtained by measuring the position-dependent probe absorption when the atom interacts with three orthogonal standing-wave fields. It is found that the precision of the atom localization depends sensitively on the probe detuning and the strength of the microwave field. Remarkably, the localization precision can be significantly improved by increasing the amplitude of the microwave field, and the localization position will be changed by adjusting the relative phase between standing-wave, microwave, and control fields.

Two-Photon Excitation of Launched Cold Atoms in Flight

Rene Gonzalez, Eduardo Alejandro, Anne Goodsell, Engama E, and e erwin

Doc ID: 286621 Received 14 Feb 2017; Accepted 11 Apr 2017; Posted 18 Apr 2017  View: PDF

Abstract: We demonstrate two-photon bi-chromatic excitation of cold rubidium atoms in flight, using the pathway $5S_{1/2}\rightarrow5P_{3/2}\rightarrow5D_{5/2}$ with two resonant photons. In our experiment, $^{85}$Rb atoms are laser-cooled in a magneto-optical trap and launched upward in discrete clouds with a controllable vertical speed of 7.1$\pm$0.6 m/s and a velocity spread that is less than 10\% of the launch speed. Outside the cooling beams, as high as 14 mm above the original center of the trap, the launched cold atoms are illuminated simultaneously by spatially-localized horizontal excitation beams at 780 nm ($5S_{1/2}\rightarrow5P_{3/2}$) and 776 nm ($5P_{3/2}\rightarrow5D_{5/2}$). We monitor transmission of the 780-nm beam over a range of intensities of 780-nm and 776-nm light. As the center of the moving cloud passes the excitation beams, we observe as much as 97.9$\pm$1.2\% transmission when the rate of two-photon absorption is high and the $5S_{1/2}$ and $5P_{3/2}$ states are depopulated, compared to 87.6$\pm$0.9\% transmission if only the 780-nm beam is present. This demonstrates two-photon excitation of a launched cold-atom source with controllable launch velocity and narrow velocity spread, as a foundation for three-photon excitation to Rydberg states.

Instrumentation limitation on a polarisation-based entangled photon source

Yaseera Ismail, Stuti Joshi, Andrew Forbes, and Francesco Petruccione

Doc ID: 284166 Received 06 Jan 2017; Accepted 11 Apr 2017; Posted 11 Apr 2017  View: PDF

Abstract: Free-space optical communication is hindered by turbulence resulting in spatial modal dispersion of the optical beam. Here we mimic in the laboratory the far field turbulence effects on entangled photons in the polarisation basis. We make use of a diffractive optical element to simulate turbulence distortions and measure the entanglement as a function of the turbulence strength. We show that the standard method of coincidence detection using single mode fibre coupling to single photon counters results in spatial mode dependence of entanglement even though it is not measured with spatial modes. We find that the overall coupling inefficiency of the detected coincidence caused by spatial mode dispersion in free space can be corrected by the use of multimode fibre. Our results suggest that care is required in the choice of detection system for free space quantum communication systems.

Analysis of Free carrier effects on MI in Silicon-On-Insulator Nano-waveguides

Deepa Chaturvedi, Ajit Kumar, and Akhilesh Mishra

Doc ID: 284777 Received 13 Jan 2017; Accepted 11 Apr 2017; Posted 11 Apr 2017  View: PDF

Abstract: We present a comprehensive theoretical study on the effects of two photon absorption (TPA), free-carrier-induced loss and high order dispersion (HOD) on the modulational instability (MI) at low input powers in silicon-on-insulator (SOI) nano-waveguides. The MI analysis is carried out in both the normal and the anomalous dispersion regimes at tele-communication wavelength. To realize the two different kinds of dispersion, anomalous and normal, two different waveguide structures have been considered. Further, the effect of carrier life time and power dependence on MI gain spectra have also been delineated.

Parametric wave mixing enhanced by velocity insensitive two-photon excitation in Rb vapour

Alexander Akoulchine, Dmitry Budker, and Russell McLean

Doc ID: 285956 Received 31 Jan 2017; Accepted 10 Apr 2017; Posted 11 Apr 2017  View: PDF

Abstract: We demonstrate how the orientation of the Rb cell can significantly affect the intensity and spectral characteristics of both the frequency up- and down-converted fields generated by nonlinear processes in Rb vapour. The efficiency of parametric wave mixing in Rb vapour excited to the 5D5/2 level by two-colour resonant laser light can be significantly increased by seeding the excitation region with coherent and directional radiation at 5. µm that is resonant with the population inverted 6P3/2 -5D5/2 transition. It has been shown that the process of velocity insensitive two-photon excitation is central to understanding the observed coherent blue and mid-IR light enhancements and that the velocity insensitive and velocity selective two-photon excitations could produce two co-existing but spectrally and spatially distinguishable mid-IR fields at 5. µm.

Red diode pumped Cr:Nd:GSGG laser: two-color mode-locked operation

Talha Yerebakan, Umit Demirbas, STEFAN EGGERT, Rainer Bertram, Peter Reiche, and Alfred Leitenstorfer

Doc ID: 284761 Received 17 Jan 2017; Accepted 10 Apr 2017; Posted 11 Apr 2017  View: PDF

Abstract: We have investigated in detail the continuous-wave (cw) and mode-locked performance of a diode pumped Cr:Nd:GSGG laser. State-of-the-art single-mode and multimode laser diodes around 665 nm were used as pump sources. In cw operation, we have demonstrated lasing thresholds as low as 14 mW, slope efficiencies as high as .4%, and output powers up to 738 mW. The free running emission wavelength was 1061 nm. With a birefringent tuning plate, lasing could also be obtained at 1051 nm, 1058 nm, 1065 nm, 1068 nm, 1072 nm, 1103 nm and 1111 nm lines. A saturable Bragg reflector (SBR) was used to initiate and sustain mode locking where the Cr:Nd:GSGG laser produced 6-ps long pulses around 1061 nm with an average power of 160 mW. The repetition rate was 142.65 MHz, resulting in pulse energies of 1.1 nJ and peak powers of 175 W. Dual-wavelength simultaneous mode-locked operation was also shown for the 1058 nm & 1061 nm lines at an average power of 45 mW.

Evaluation and design of a large-scale cloaking device by Hamiltonian-based ray-tracing method. Part I: Full-mesh representation

Osamu Matoba and Tatsuo Tanaka

Doc ID: 284128 Received 06 Jan 2017; Accepted 10 Apr 2017; Posted 11 Apr 2017  View: PDF

Abstract: A Hamiltonian-based ray tracing technique is applied to the evaluation of the performance of cloaking devices with arbitrary shapes based on full-mesh representation. The constitutive parameters of cloaking devices are calculated by the finite element method. Cloaking characteristic of double cylindrical cloaking device is evaluated. The numerical results showed that fine mesh structure is required for better cloaking performance. Full mesh representation is useful for fabrication design.

Magnetic field concentration with coaxial silicon nanocylinders in optical spectral range

Kseniia Baryshnikova, Andrey Novitsky, Andrey Evlyukhin, and alexander sahlin

Doc ID: 286612 Received 14 Feb 2017; Accepted 07 Apr 2017; Posted 11 Apr 2017  View: PDF

Abstract: Resonant magnetic energy accumulation is theoretically investigated in the optical and near infra-red region. It is demonstrated that the silicon nanocylinders with and without coaxial through holes can be used for the control and manipulation of optical magnetic fields providing up to 26 fold enhancement of these fields for the considered system. Magnetic field distributions and dependence on the parameters of nanocylinders are revealed at the wavelengths of magnetic dipole and quadrupole resonances responsible for the enhancement. Obtained results can be applied, for example, to design nanoantennas for detection of atoms with magnetic optical transitions.

Ultrashort high amplitude dissipative solitons in the presence of higher order effects

Sofia Latas, Mario F.S. Ferreira, and Margarida Facao

Doc ID: 286025 Received 02 Feb 2017; Accepted 05 Apr 2017; Posted 05 Apr 2017  View: PDF

Abstract: In this work, the propagation of high-amplitude solitons of the cubic-quintic complex Ginzburg-Landau equation in the presence of higher order effects, namely, the intra-pulse Raman scattering (IRS) and the third order dispersion (TOD) has been studied. Starting from a singularity found by Akhmediev and co-workers, high amplitude pulses are predicted using a perturbation approach and numerically obtained. We have found that this singularity is no longer present if the intra-pulse Raman scattering effect is considered and zero velocity pulses may be achieved in the presence of both IRS and TOD. The predictions from perturbation theory are numerically confirmed to a certain extent.

Evaluation and design of a large-scale cloaking device by Hamiltonian-based ray-tracing method. Part II: Design of the Distribution of Constitutive Parameters

Osamu Matoba and Tatsuo Tanaka

Doc ID: 284131 Received 06 Jan 2017; Accepted 04 Apr 2017; Posted 05 Apr 2017  View: PDF

Abstract: Improvement of cloaking performance by design of distributions of constitutive parameters is investigated. The distributions are changed by employing the Navier’s equation with various distributions of Young modulus as the partial differential equation for the solution of Jacobian transformation matrix used in the transformation optics. The cloaking performances are evaluated by Hamiltonian-based ray tracing. The numerical results show the proposed design method can improve the cloaking performance. The design method can contribute to realizing cloaking devices with large scale by taking account of the finite resolution of the manufacture.

Simple fringe illumination technique for optical super resolution

Anwar Hussain, Tariq Amin, Cuifang Kuang, Liangcai Cao, and Xu Liu

Doc ID: 282099 Received 02 Dec 2016; Accepted 17 Mar 2017; Posted 21 Mar 2017  View: PDF

Abstract: The simple and precise fringe illumination technique is implemented to retrieve the missing information of two-dimensional object. The object placed in a 4f optical system illuminated with fringes, generated by a reflective-mode Spatial Light Modulator (SLM). A set of three fringes, shifted in phase, sequentially illuminate the object and correspondingly three images are captured through CCD. The fringes illuminate the object and higher spatial frequencies, primarily lies outside the aperture along horizontal direction heterodyne into the pass band. To heterodyne higher spatial frequencies lies in vertical direction, the fringes are swapped by 90 degree and three images captured through CCD. These recorded images processed to retrieve the object information using explicit algorithm. The final image is higher in resolution compared to the band-limited image. For validity of the technique, the theoretical concept simulated and supported with experimental results.

Green formulation for studying electromagnetic scattering from graphene--coated wires of arbitrary section

Claudio Valencia, Mauro Cuevas, Eduardo Riso, and Ricardo Depine

Doc ID: 282163 Received 05 Dec 2016; Accepted 20 Feb 2017; Posted 28 Mar 2017  View: PDF

Abstract: We present a rigorous electromagnetic method based on Green’s second identity for studying the plasmonic response of graphene–coated wires of arbitrary shape. The wire is illuminated perpendicular to its axis by a monochromatic electromagnetic wave and the wire substrate is homogeneous and isotropic. The field is expressed everywhere in terms of two unknown source functions evaluated on the graphene coating which can be obtained from the numerical solution of a coupled pair of inhomogeneous integral equations. To assess the validity of the Green formulation, the scattering and absorption efficiencies obtained numerically in the particular case of circular wires are compared with those obtained from the multipolar Mie theory. An excellent agreement is observed in this particular case, both for metallic and dielectric substrates. To explore the effects that the break of the rotational symmetry of the wire section introduces in the plasmonic features of the scattering and absorption response, the Green formulation isapplied to the case of graphene-coated wires of elliptical section. As might be expected from symmetry arguments, we find a two-dimensional anisotropy in the angular optical response of the wire, particularly evident in the frequency splitting of multipolar plasmonic resonances. The comparison between the spectral position of the enhancements in the scattering and absorption efficiency spectra for low–eccentricity elliptical and circular wires allows us to guess the multipolar order of each plasmonic resonance. We present calculations of the near field distribution for different frequencies which explicitly reveal the multipolar order of the plasmonic resonances. They also confirm the previous guess and serve as a further test on the validity of the Green formulation.

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