Accepted papers to appear in an upcoming issue
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Spontaneous parametric four wave mixing and fluorescence lifetime manipulation in Diamond NV Center
GHULAM KHAN, Irfan Ahmed, Faizan Raza, Ruimin Wang, Changbiao Li, and Yanpeng Zhang
Doc ID: 332382 Received 24 May 2018; Accepted 18 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: We report the lifetime of spontaneous parametric four wave mixing (SP-FWM) and multi-order fluorescence in two, three and four level atomic system of negatively charged nitrogen vacancy in diamond. The lifetime of SP-FWM is enhanced at high power by induced dark state from coupling fields. The reduction and enhancement in fluorescence lifetime is attributed to destructive and constructive quantum interference, respectively. The quantum interference is induced by interaction among different decay pathways of spontaneous emission by closely spaced energy levels, which can be controlled by dipole-dipole interaction and the mutual orientations of dipole moments. The lifetime is observed to be longer in two level as compare to three level and four level atomic systems. The different measured lifetimes suggests the sensitivity of these atomic systems to quantum interference and dressing effect. These outcomes may provide new insights in development of all-optical communication devices and quantum storage on photonic chips.
The role of the Raman gain in the noise dynamics of all-normal dispersion silica fiber supercontinuum generation
Iván Bravo Gonzalo and Ole Bang
Doc ID: 332385 Received 25 May 2018; Accepted 17 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: We theoretically and numerically study the influence of the Raman gain profile on the noise dynamics of the supercontinuum generation in a standard all-normal dispersion silica fiber using the scalar generalized nonlinear Schrödinger equation. In particular, we investigate the effect of the different secondary resonance gain peaks on the evolution of the SC coherence by comparing the coherence obtained when using the measured Raman gain with that obtained using different analytical approximations. We demonstrate that the strongest secondary peak at 14.8 THz has a significant influence in that it leads to an early development of a decoherence band on the long wavelength side of the SC. In contrast, the decoherence is strongly dominated by the short wavelength side below the pump for all analytical models not taking this 14.8 THz gain peak into account.
Anomalous zero-group-velocity photonic bondingstates with local chirality
Moïse Sotto, Kapil Debnath, Ali Khokhar, Isao Tomita, David Thomson, and Shin-ichi Saito
Doc ID: 330361 Received 27 Apr 2018; Accepted 16 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: Photonic Crystal Waveguides (PCWs) are promising candidates for the basic building blocks of quantum information processing because they support circular polarization points that can unbalance the directionality of an integrated quantum emitter (QE). Nevertheless, the Purcell effect at circular polarization points saturates near the band-edge, the preferred region for Quantum ElectroDynamics (QED). Consequently, chirality and ultra-strong light-matter interaction are difficult to combine.Here, we detract from the vicinity of the band-edge, and couple modes with different parities by breaking the mirror symmetry.Using three-dimensional finite-difference time domain method (3D-FDTD), simulated bandstructures of the implemented Photonic Bonding States (PBS) display single-mode anomalous zero-group-velocity (ZGV) points far from the band edge. The electric field patterns of these points feature circular polarization points at high field intensity regions where a QE would acquire uni-directional emission behavior.Fabricated devices in Silicon (Si) slabs demonstrate the predicted coupling energy between the modes and the signature of single-mode anomalous ZGV points.This method to engineer PBS in PCWs paves the way for outperforming chiral light-matter experiment on-chip.
Enhancement of backward third-harmonic generation in a one-dimensional PIM/NIM periodic structure
Prathan Buranasiri, Surawut Wicharn, and Witoon Yindeesuk
Doc ID: 334316 Received 04 Jun 2018; Accepted 14 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: A numerical simulation is reported for backward third-harmonic generation (BTHG) in a one-dimensional periodic structure containing a stack composed of positive-index material (PIM) and negative-index material (NIM). A multiple-scale method is used to formulate a completed set of coupled-mode equations with inhomogeneous higher-order nonlinear terms for both electric and magnetic fields. The coupled equations are numerically solved to simulate output third-harmonic frequency pulses and their conversion efficiencies by a fast Fourier transform-pulse propagation method. Finally, the numerical results validate the idea that using a combination of negative-index phase-matched condition, which is created by engineering dispersive property of NIM layer, and local field enhancement, which is created by arranging PIM and NIM layers in an optimal periodic fashion, thus yielding a dramatic enhancement of BTHG conversion efficiency.
Hyperbolic Metamaterial Resonator-Antenna Scheme for Large, Broadband Emission Enhancement and Single Photon Collection
Faraz Inam, Nadeem Ahmed, Michael Steel, and stefania castelletto
Doc ID: 332650 Received 29 May 2018; Accepted 13 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: We model the broadband enhancement of single-photon emission from color centres in silicon carbide nanocrystals coupled to a planar hyperbolic metamaterial (HMM) resonator. The design is based on positioning the single photon emitters within the HMM resonator, made of a dielectric index-matched with silicon-carbide material. The broadband response results from the successive resonance peaks of the lossy Fabry-Perot structure modes arising within the high-index HMM cavity. To capture this broadband enhancement in the single photon emitter’s spontaneous emission, we placed a simple gold based cylindrical antenna on top of the HMM resonator. We analyzed the performance of this HMM coupled antenna structure in terms of the Purcell enhancement, quantum efficiency, collection efficiency and overall collected photon rate. For perpendicular dipole orientation relative to the interface, the HMM coupled antenna resonator leads to a significantly large spontaneous emission enhancement with Purcell factor of the order of 250 along with a very high average total collected photon rate (CPR) of about 30 over a broad emission spectrum (700 nm – 1000 nm). The peak CPR increases to about 80 at 900 nm, corresponding to the emission of silicon-carbide quantum emitters. This is a state-of-the art improvement considering the previous computational designs have reported a maximum average CPR of 25 across the nitrogen-vacancy centre emission spectrum, 600 nm to 800 nm with the highest value being about 40 at 650 nm.
Quantitative circuit model of patch-based nanoantenna-enabled detectors
Salvatore Campione, Larry Warne, Michael Goldflam, David Peters, and Michael Sinclair
Doc ID: 325998 Received 16 Mar 2018; Accepted 13 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: Improving the sensitivity of infrared detectors is an essential step for future applications, including satellite- and terrestrial-based systems. We investigate nanoantenna-enabled detectors (NEDs) in the infrared, where the nanoantenna arrays play a fundamental role in enhancing the level of absorption within the active material of a photodetector. The design and optimization of nanoantenna-enabled detectors via full-wave simulations is a challenging task given the large parameter space to be explored. Here, we present a fast and accurate fully analytic circuit model of patch-based NEDs. This model allows for the inclusion of real metals, realistic patch thicknesses, non-absorbing spacer layers, the active detector layer, and absorption due to higher order evanescent modes of the metallic array. We apply the circuit model to the design of NED devices based on type II superlattice absorbers, and show that we can achieve absorption of ~70% of the incoming energy in subwavelength (~λ/5) absorber layers. The accuracy of the circuit model is verified against full-wave simulations, establishing this model as an efficient design tool to quickly and accurately optimize NED structures.
Broadband and polarization independent asymmetric transmission of visible light through three dimensional trapezoidal metallic metasurface
Ahmet Ozer, Hasan Kocer, and Hamza Kurt
Doc ID: 328400 Received 13 Apr 2018; Accepted 13 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: In modern optical applications, it has become an important need to flow light unidirectionally. Optical diode realizes this task as an electrical counterpart manipulates the flow of electrons in semiconductor materials. In this study, we show a broadband and polarization independent optical diode-like mechanism in metasurface configuration in the visible spectrum. The approach is passive such that the operating principle does not depend on any type of external biasing scheme. The constituted metasurface composed of a periodic type three-dimensional nano array of trapezoidal shaped aluminum metal on a sapphire substrate is designed to produce desired optical response for opposite directions of illumination. The optical transmission properties were systematically investigated using finite-difference time-domain computations. Asymmetric transmission frequency interval of the designed metasurface is associated with the Wood-Rayleigh Anomaly and physical principle lies in the generation of different number of higher order modes upon oppositely incident light. Our design has forward transmission greater than 50%, backward transmission less than 28% and contrast ratio greater than 3 dB in the entire visible spectrum. Specifically, the maximum forward transmission of 88% at 550 nm wavelength and a very high contrast ratio (~ dB) at a wavelength of 461 nm were obtained. It is numerically shown that the asymmetric transmission has been directly related to the appearance of high-order diffractions for only one direction excitation case. This study provides a path toward the realization of optical diodes for the applications, such as optical communication and laser systems.
Modal gain equalization of 18 modes using single-trench ring-core EDFA
Ankita Gaur and Vipul Rastogi
Doc ID: 324869 Received 26 Feb 2018; Accepted 13 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: Few mode erbium doped fiber amplifier (FMEDFA) is a key component of few mode fiber (FMF) based optical communication system to allow the simultaneous amplification of all signal mode groups. This article proposes the single-trench ring-core FMEDFA for gain equalization of five signal mode groups LP01, LP11, LP21, LP31 and LP41. The proposed fiber with ring-core Er^+3 doping and fundamental pumping is used to study the gains and differential modal gains (DMGs) of signal mode groups. In this study, we have shown that introduction of trench increases the modal confinement of higher mode groups and decreases that of lower mode groups in ring region (or doped region) slightly. This helps in controlling the DMG and also increases the effective index difference ∆neff between the adjacent modes. We show that at 1530 nm signal wavelength, DMG of five mode groups is reduced from 1.32 dB (without trench) to 0.45 dB (with trench) with gain in excess of 20 dB. Also, the mode spacing ∆neff increases from 4.9× 10^-4 to 5.1 × 10^-4. Over the C-band, we have achieved more than 20 dB amplification and nearly 1 dB gain excursion while maintaining sufficient mode spacing ∆neff > 5.1× 10^-4 to avoid mode coupling due to macro-bending.
One- and two-dimensional electromagnetically induced grating beyond the multi-photon resonance condition
Azar Vafafard and Mostafa Sahrai
Doc ID: 325866 Received 13 Mar 2018; Accepted 11 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: We present a theoretical study for generation the electromagnetically induced grating (EIG) based on Zeeman coherence oscillations in a duplicated two-level atomic system. We show that the pure amplitude grating with efficiency about 100% in zero order is obtained in the proposed model. Transferring of light energy from zero order to high orders occurs in this system by tuning the intensity and detuning of the coupling field. Physical mechanisms of the results are discussed by the means of beyond multi-photon resonance condition. Additionally, two-dimensional EIG can be created in duplicated two-level system by splitting the coupling field into two orthogonal components. The optical properties of designed two-dimensional grating are also controlled by the intensity and detuning of the coupling field.
Modulation instability in 2D waveguide arrays withalternating sign of refraction index
Kuppusamy Porsezian, Shafeeque A K, and Andrei Maimistov
Doc ID: 332750 Received 29 May 2018; Accepted 11 Jul 2018; Posted 12 Jul 2018 View: PDF
Abstract: We consider the propagation of coupled forward and backward waves in two dimensional arrays of alternatingwaveguides with positive and negative refractive indices. The array has the cross section in theform of face-centered square lattice. The unit cell consists of three different waveguides with differentoptical properties. We obtain the condensate solutions for electromagnetic pulse propagation in such arrayof waveguides. The base equations describing this model have the solution that corresponds to thestatic and homogeneous intensity distribution on the waveguides. The stability of these solution in bothnormal and anomalous dispersion regimes are also investigated using the modulation instability analysis.
High-energy ultrashort stretched pulse all-fiber erbium-doped ring laser with an improved free-running generation stability
Dmitriy Dvoretskiy, Stanislav Sazonkin, ILYA O. OREKHOV, Igor Kudelin, Alexey Pnev, Valeriy Karassik, Alexandr Krylov, and Lev K. Denisov
Doc ID: 330558 Received 27 Apr 2018; Accepted 11 Jul 2018; Posted 12 Jul 2018 View: PDF
Abstract: We report on the stable stretched pulses generation with a duration ~ 180 fs at a central wavelength of 1560 nm with an 30 mW average output power at a repetition rate ~ 11.3 MHz (with a signal-to-noise ratio at a fundamental frequency ~ 59 dB) with an Allan deviation of the pulse repetition frequency ~ 5.75·10^-9 for 1 s interval and a relative intensity noise < -101 dBc / Hz (30 Hz-1000 kHz). This corresponds to the < 14.7 kW maximum peak power and < 2.6 nJ maximum available pulse energy obtained immediately from the highly-nonlinear all-fiber laser resonator.
Four-wave mixing in air by bichromatic spectrally broadened femtosecond laser pulses
Virgilijus Vaicaitis and Viktorija Tamuliene
Doc ID: 331214 Received 08 May 2018; Accepted 11 Jul 2018; Posted 12 Jul 2018 View: PDF
Abstract: The broadband infrared (in the range of 2 mm) and visible radiations were generated in air by focused two colour (wavelengths of about 791 nm and 1.2-1.6 mm, respectively) femtosecond laser pulses. The spectral and angular properties of the radiation generated in both spectral ranges allowed us to interpret it as a result of the interplay between spectral broadening and cascaded four-wave mixing of the incident and frequency-shifted light fields. Results of the numerical modelling of the propagation equation includingthe nonlinear Kerr term agrees well with the experiment.
Shock Physics at the Nanoscale
Doc ID: 332074 Received 18 May 2018; Accepted 10 Jul 2018; Posted 12 Jul 2018 View: PDF
Abstract: Shock waves can achieve extreme states of pressure and temperature, of particular interest because those conditions can result in non-equilibrium material dynamics that evolve on ultrafast timescales. Examples of such phenomena include shock-induced chemistry and phase transitions. Traditional plate impact methods lack the necessary time and space resolution needed to observe the onset of ultrafast nanoscale phenomena. Sub-picosecond time scale and nanometer spatial scale shock compression and diagnostics methods have been developed to surmount such difficulties. This paper reviews a number of nanoscale shock wave generation methods, as well as the diagnostics that are applicable at these restrictive time and spatial scales.
Photosensitive center in CdTe:Sn: Photorefractive, spectroscopic, and magnetooptical studies
Konstantin Shcherbin, Serguey Odoulov, Francois Ramaz, Dean Evans, and Bernard Briat
Doc ID: 332395 Received 24 May 2018; Accepted 10 Jul 2018; Posted 12 Jul 2018 View: PDF
Abstract: Photorefractive properties of tin-doped CdTe crystals are studied. The material demonstrates sensitivity for low-intensity recording. One-center model of the space-charge formation perfectly describes the experimental results. Tin impurity center is characterized using the data of optical absorption and lightinduced absorption spectroscopy, pseudo 3-D mapping of the photoabsorption, magnetic circular dichroism and optical detection of magnetic resonance. Spectroscopic studies confirm appropriateness of the one-center model for describing the space charge formation with tin as a main photorefractive center. Optical ionization (neutralization) energies are estimated for phototransitions from Sn+ (1.14 eV) and Sn0 (1.09 eV). Possible ways for improvement of the photorefractive performances are discussed.
Multiple PT symmetry and tunable scattering behaviors in a heterojunction cavity
Feng Gao, Jia-Rui Dong, Yimou Liu, Yan Zhang, and Jin-Hui Wu
Doc ID: 320750 Received 31 Jan 2018; Accepted 09 Jul 2018; Posted 12 Jul 2018 View: PDF
Abstract: We study a heterojunction cavity with one vacuum gap inserted between two dielectric slabs of conjugate complex refractive indices, i.e. of balanced gain and loss. This cavity is found to exhibit a multiple PT symmetry characterized by alternate symmetric and broken phases when examined in terms of both eigenvalues of the scattering matrix. Scattering behaviors including reflection and transmission, however, should be classified into three distinct types because a transition region may exist between the symmetric and broken phases. It is of particular interest that vanishing reflectance could occur for light waves input from both left and right sides, though of different wave vectors, in the symmetric phases. Moreover, it is viable to attain unidirectional invisibility for light waves only input from the left side and simultaneously realize coherent perfect absorption and lasing for a given wave vector in the transition regions. These unique scattering behaviors can be easily tuned to suit a wide range of wave vectors by adjusting the gap width.
Up-conversion single-photon detectors based on integrated PPLN waveguides- Invited
Fei Ma, Longyue Liang, Jiupeng Chen, Yang Gao, Ming-Yang Zheng, Xiuping Xie, Hong Liu, Qiang Zhang, and Jian-Wei Pan
Doc ID: 331169 Received 23 May 2018; Accepted 09 Jul 2018; Posted 18 Jul 2018 View: PDF
Abstract: We demonstrate up-conversion single-photon detectors based on integrated periodically poled lithium niobate waveguides, which incorporate two mode filters and a directional coupler. The two mode filters are optimized for the fiber-waveguide coupling efficiencies for 1550 nm and 1950 nm respectively while the directional coupler plays the role of wavelength combiner, making the overall system portable and low-cost. The two wavelengths pump each other in our detection system. We achieve detection efficiencies of 28% for 1550 nm and 27% for 1950 nm, respectively. This scheme provides an efficient integrated single-photon detection method for any two well-separated spectral bands in the whole low-loss range of lithium niobate waveguides.
A compact frequency-stabilized pump laser for wavelength conversion in long-distance quantum communication
Kohei Ikeda, Yusuke Hisai, Kazumichi Yoshii, Hideo Kosaka, Feng-Lei Hong, and Tomoyuki Horikiri
Doc ID: 326543 Received 21 Mar 2018; Accepted 04 Jul 2018; Posted 06 Jul 2018 View: PDF
Abstract: We demonstrate a compact frequency-stabilized laser at 1064 nm using Doppler-free saturation absorption spectroscopy of molecular iodine. The achieved laser frequency stability and linewidth are 5.7 10-12 (corresponding to an absolute frequency of 1.6 kHz) and 400 kHz, respectively. The developed frequency-stabilized laser can be used as a pump laser for wavelength conversion from visible to telecom (or vice versa) to connect quantum memories utilizing nitrogen-vacancy centers in diamond at remote nodes in fiber-based quantum communication.
Low-loss forward and backward surface plasmons in a semiconductor nanowire coated by helical graphene strips
Vladimir Tuz, Volodymyr Fesenko, and Vitalii Shcherbinin
Doc ID: 332193 Received 21 May 2018; Accepted 04 Jul 2018; Posted 06 Jul 2018 View: PDF
Abstract: In the long-wavelength approximation, the effective conductivity tensor is introduced for graphene ribbons (strips) placed periodically at the interface between two media. The resulting conducting surface is considered as a coating for semiconductor nanowire. For the hybrid waves of such nanowire the dispersion equations are obtained in explicit form. Two types of surface plasmons are found to exist: (i) the modified surface plasmons, which originate from the ordinary surface plasmons of a graphene-coated semiconductor nanowire, and (ii) the spoof plasmons, which arise on the array of graphene ribbons and may possess forward-wave and backward-wave dispersion. It is revealed that the spoof surface plasmons are low-loss ones, and their frequencies, field-confinement and group velocities can be tuned widely by adjusting the coil angle and width of helical graphene strips.
Controlling the Trajectories of Self-Written Waveguides in Photopolymer
Ra'ed Malallah, Haoyu Li, Inbarasan Muniraj, Derek Cassidy, Nebras Alattar, John Healy, and John Sheridan
Doc ID: 327832 Received 12 Apr 2018; Accepted 03 Jul 2018; Posted 06 Jul 2018 View: PDF
Abstract: The diffraction of a light beam as it propagates through a medium can be effectively compensated by self-trapping. A laser beam propagating through a nonlinear medium can generate a waveguiding action, i.e. a higher refractive index, along the direction of the light propagation. Experiments involving light beams illuminating the front surface of a solid bulk photopolymer sample are reported. The self-bending of parallel beams, (input simultaneously but separated in space), during the resulting self-writing process are studied. It is shown that there is strong correlation between the initial beam input separation distance and the resulting waveguide trajectories taken during channel formation. Finite element-based simulations are performed that predict the self-writing waveguides formation process, e.g. beam focusing, trapping and the deviations of the waveguide trajectories caused by adjacent beams. The model is shown to be in good qualitative agreement with observed experimental results.
Theoretical modeling of photo-induced lens formation in a polymerizable matrix containing quantum dots
Svitlana Bielykh, Tigran Galstian, and Victor Reshetnyak
Doc ID: 331461 Received 11 May 2018; Accepted 03 Jul 2018; Posted 06 Jul 2018 View: PDF
Abstract: We present a theoretical model describing the dynamic modulation of the refractive index of quantum dot (QD) containing photo polymerizable mixture under the spatially non-uniform illumination. The case of a laser beam with Gaussian spatial intensity distribution is used to model the process of non-uniform polymerization, followed by the processes of diffusion of monomers, polymers and QDs. This results in the creation of a lens-like refractive index transversal distribution. The contribution of QDs is taken into account by using the conservation of the sum of volume fractions of polymers, monomers and QDs. Dynamic variations of different parameters influencing the lens formation and the focal length of the lens are obtained. In particular, it is shown how the change of time of irradiation varies the profile of the refractive index and, hence, controls the focal length of the lens.
Optical Phase Control of Coherent Pulse Stacking via Modulated Impulse Response
Yawei Yang, Lawrence Doolittle, Almantas Galvanauskas, Qiang Du, gang huang, John Ruppe, Tong Zhou, Russell wilcox, and Wim Leemans
Doc ID: 331880 Received 24 May 2018; Accepted 02 Jul 2018; Posted 03 Jul 2018 View: PDF
Abstract: To stabilize the combined pulse energy for coherent temporal pulse stacking using interferometer cavities, we have developed a direct cavity phase measurement method, based on analysis of response to modulated probe pulses. An experiment has demonstrated optical phase control within 50 mrad for four cavities, resulting in combination of 25 pulses with 1.5% RMS stability over 30 hours.
The effects of Mn doping on the structural, linear and nonlinear optical properties of ZnO nanoparticles
Fahimeh Abrinaei and Nasiben Molahasani
Doc ID: 332547 Received 24 May 2018; Accepted 01 Jul 2018; Posted 06 Jul 2018 View: PDF
Abstract: In this study, we reported on the synthesis and characterization of ZnO and Mn-doped ZnO nanoparticles (NPs) with 2, 5 and 15% Mn/ZnO prepared using the hydrothermal method. The morphological and structural properties of the Mn-doped ZnO NPs were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), and Fourier-transform infrared spectroscopy (FTIR). X-ray diffraction patterns indicate that all of the samples have hexagonal wurtzite structure. The average diameters of Mn-doped ZnO NPs with different Mn ratios were estimated about 20-38 nm from FESEM images. Linear absorption coefficient and optical band gap energy of ZnO and Mn: ZnO NPs were calculated using UV-VIS spectroscopy. A decrease in Eg was observed by an increase in Mn concentration. The nonlinear optical (NLO) measurements have been performed using a nanosecond Nd: YAG pulse laser by the Z-scan technique. Both pure and Mn-doped ZnO NPs exhibited a negative NLO index of refraction at 532 nm which is related to a self-defocusing phenomenon. The NLO absorption of ZnO and Mn: ZnO NPs is attributed to two-photon absorption (TPA) combined with free carrier absorption. Furthermore, the third-order nonlinear susceptibilities of pure and Mn-doped ZnO NPs were varied between 1.2- 2.5×10−9 esu, depending on Mn contents. The results suggest that ZnO and Mn: ZnO NPs synthesized by the hydrothermal method may be a promising candidate for the NLO applications at 532 nm as well as Mn dopant can improve the NLO properties of ZnO NPs.
Simulation of a multimode fiber interferometer using averaged characteristics approach
Oleg Kotov, Mikhail Bisyarin, Ivan Chapalo, and Alexander Petrov
Doc ID: 314998 Received 05 Dec 2017; Accepted 01 Jul 2018; Posted 03 Jul 2018 View: PDF
Abstract: A new method of analytical representation and numerical simulation of multimode fiber interferometer signals is developed. A system of averaged normalized characteristics, called amplitude and spectral characteristics, is introduced for this end. Interferometer signals generated by fiber length variation or laser frequency modulation were investigated at various parameters of the fiber. Joint usage of amplitude and spectral characteristics proved to substantially broaden dynamical range of measurements of weak and strong external disturbances of the fiber. The method may be used for analysis and design of various optical sensor schemes with multimode fiber interferometers. It is also usable for estimating modal noise characteristics in optical systems with undesirable effects of intermodal interference.
Lasing of optically pumped large droplets: instant and gradual blue shift
Mihai Pascu, Mihai Boni, Ionut Andrei, and Angela Staicu
Doc ID: 326209 Received 16 Mar 2018; Accepted 29 Jun 2018; Posted 29 Jun 2018 View: PDF
Abstract: Results about the interaction of 532 nm pulsed laser beam with individual pendant Rhodamine 6G dye droplets of large size parameter, x ≈ 7300, are reported. By varying dye concentration and pumping energy are obtained typical fluorescence bands detected in such cases and a narrow, instantly or gradually blue shifted band assigned to lasing effect at droplet surface. The maximum blue shift value of the lasing peak wavelength is associated with the maximum of dye fluorescence gain curve when self-absorption effects are not present. Lasing peak position is not further influenced by pumping energy or droplet diameter decrease after lasing reaches the wavelength of gain curve peak.
Goos-Hänchen shift for Gaussian beams impinging on monolayer MoS₂-coated surfaces
Akash Das and Manik Pradhan
Doc ID: 330562 Received 30 Apr 2018; Accepted 29 Jun 2018; Posted 29 Jun 2018 View: PDF
Abstract: We report a detailed theoretical study of the Goos-Hänchen (GH) shift for a fundamental Gaussian beam on the surface coated with monolayer molybdenum disulfide (MoS₂), a promising two-dimensional transition metal dichalcogenide (2D-TMDC) and a direct band-gap semiconductor. A general model has been developed to predict the GH shifts on monolayer MoS₂-coated surfaces for light beam with different wavelengths. In contrary to the conventional GH shift which is observed for total internal reflection only, here we predict finite spatial and angular GH shift for both partial (PR) and total internal reflection (TIR) conditions. Our analysis revealed that the observation of the giant negative spatial GH shift on MoS₂-coated surfaces is attributed to the surface conductivity of MoS₂ monolayer which has never been explored before. Furthermore, we find that the GH shifts are dependent on the mode of polarization, the wavelength of incident beam along with the nature of surfaces. This deepens our understanding of the unusual behaviour of GH shift near the Brewster’s angle as well as the critical angle of incidence. We expect that our findings will lead to several new applications of MoS₂ in sensors and device technology.
On sensitivity limitations of a dichromatic optical detection of a classical mechanical force
Andrey Matsko and Sergey Vyatchanin
Doc ID: 331647 Received 14 May 2018; Accepted 29 Jun 2018; Posted 29 Jun 2018 View: PDF
Abstract: We apply the strategy of the back action evading measurement of a quadrature component of mechanical motion of a test mass to detection of a classical force acting on the mass (1) and study both classical and quantum limitations of the technique. We are considering a resonant displacement transducer interrogated with a dichromatic optical pump as a model system in this study. The transducer is represented by a Fabry Perot cavity with a totally reflecting movable end mirror the resonant force of interest acts upon. The cavity is pumped with two coherent optical carriers equally detuned from one of the cavity resonances. We show that the quantum back action cannot be completely excluded from the measurement result due to the dynamic instability of the opto-mechanical system that either limits the allowable power of the optical pump or calls for introducing an asymmetry to the pump configuration destroying the quantum nondemolition nature of the measurement.
Sublinearly-chirped metalenses for forming abruptly autofocusing cylindrically polarized beams
Sergey Degtyarev, Svetlana Khonina, and Sergey Volotovsky
Doc ID: 327731 Received 05 Apr 2018; Accepted 26 Jun 2018; Posted 28 Jun 2018 View: PDF
Abstract: We propose a metalens which forms an abruptly autofocusing cylindrically polarized laser beam. The main principle of the metalens is based on combining two elements: a subwavelength polarization grating and an autofocusing sublinearly-chirped lens. Subwavelength polarizing grating is calculated separately. It is shown that the grating can effectively convert linearly polarized initial beam into radially polarized beam. It is demonstrated that combining the polarization convertor and focusing phase lens, we both increase polarization conversion efficiency and decrease the quantity of optical elements in an arrangement. Wave propagation through the metalens is numerically simulated with the finite element method which is implemented in Comsol Multiphysics software. Polarization and phase conversion is calculated in the near-zone behind the metalens. Further wave propagation and focusing are simulated with Rayleath-Sommerfeld diffraction integrals. Metalenses for forming both diffraction-free and abruptly autofocusing radially-polarized beams are under investigation.
Multiphoton Discrete Fractional Fourier Dynamics in Waveguide Beam Splitters
Konrad Tschernig, Roberto Leon Montiel, Omar Magana Loaiza, Alexander Szameit, Kurt Busch, and Armando Leija
Doc ID: 332035 Received 17 May 2018; Accepted 26 Jun 2018; Posted 28 Jun 2018 View: PDF
Abstract: We demonstrate that when a waveguide beam splitter (BS) is excited by N indistinguishable photons, the arising multiphoton states evolve in a way as if they were coupled to each other with coupling strengths that are identical to the ones exhibited by a discrete fractional Fourier system. Based on the properties of the fractional Fourier transform, we then derive a multiphoton suppression law for 50/50 BSs, thereby generalizing the Hong-Ou-Mandel effect. Furthermore, we examine the possibility of performing simulta- neous multiphoton quantum random walks by using a single waveguide BS in combination with photon number resolving detectors. We anticipate that the multiphoton lattice-like structures unveiled in this work will be useful to identify new effects and applications of high-dimensional multiphoton states.
Quantum noise of parametric amplification in phase-sensitive/insensitive intermediate condition
Doc ID: 325907 Received 16 Mar 2018; Accepted 25 Jun 2018; Posted 26 Jun 2018 View: PDF
Abstract: Phase-sensitive amplification (PSA) is a particular type of optical parametric amplification (OPA), which features a low-noise property such that the quantum-limited noise figure is 0 dB. The PSA operation is typically achieved when the signal and idler spectra are degenerate in optical parametric interactions, i.e., the degenerate OPA condition. However, for a spectrally broadened incident light, these two spectra can be partially degenerate. The present work investigates the noise property of OPA in such conditions in terms of quantum mechanics. The results quantitatively indicate the intermediate properties between PSA and phase-insensitive amplification
A Lie algebraic approach to a nonstationary atom-cavity system
Jose Recamier, carlos gonzalez gutierrez, Octavio Sánchez, Ricardo Roman, and Manuel Berrondo
Doc ID: 328955 Received 20 Apr 2018; Accepted 19 Jun 2018; Posted 21 Jun 2018 View: PDF
Abstract: In this work we study the generation of photons inside an ideal cavity with resonantly oscillating boundaries in the presence of a two-level atom. We make use of Lie algebraic techniques to obtain an approximate time-evolution operator and evaluate not only the resonant and dispersive regimes but also explore different regions of parameters. We have found a very good agreement between our approximate results and those obtained by numerical means.
A fully relativistic description of the power spectrum
Doc ID: 324775 Received 26 Feb 2018; Accepted 08 Jun 2018; Posted 06 Jul 2018 View: PDF
Abstract: Resonance fluorescence of laser-driven atoms is studied in the relativistic regime by solving the time-dependent Dirac equation in a multi-levelmodel. Electron spin and retardation of the electron-photon interaction gives rise to new phenomena such as splitting of sideband peaks andmodification of the Rabi oscillator frequencies not explainable in a non-relativistic theory. In our theoretical investigation, we show how applying coherent light with x-ray frequencies, the relativistic fluorescence spectrum can be exploited to determine atomic multipole matrix elements.