Nonlinear optics, nanophotonics and plasmonics - 6Virtual room: CMC - 1
|Wednesday, May 27|
NL-6-27-1 / Understanding ionization of laser driven nanotips
* Graeme Bart, University of Ottawa, Canada
Thomas Brabec, University of Ottawa
Tunnelling of electrons from metal surfaces into free space is enabled by the presence of strong electric fields. Ultrashort laser pulses offer researchers the ability to deliver high intensity radiation over femtosecond timescales, opening up the realm of strong field physics and the atom to deeper exploration [1,2,3]. Specifically, sharp metallic nanotips have been shown to be good sources of temporally and spatially coherent electrons, as the geometry of the tip provides significant field enhancement without damage to the material, while keeping the electron emission sites localized to nanometre sized regions [4,5,6]. Moreover, these photoelectrons, once free of the metal, can be described classically by the three-step or simple man's model [7,8] and are able to be controlled on sub-cycle time scales . This attosecond control has enabled tip-enhanced electron microscopy [4,10] probing of the carrier-envelope phase of the laser pulse , and high harmonic generation . We explore the generation and dynamics of photoelectrons from sharp metal nanotips in the presence of intense ultra-fast near-infrared laser pulses on the scale of individual electrons on attosecond time scales using the Microscopic Particle-in-Cell (MicPIC)  simulation technique. Through the combination of coarse-grained features with short-range N-body interactions, MicPIC simultaneously spans atomic to micron length scales with attosecond resolution in time and is particularly well-suited to investigating circumstances involving strongly coupled plasmas. This level of detail provides a deeper look into the sub-femtosecond processes behind high harmonic generation and attosecond electron pulses in metal nanotips. The effect of tip geometry and composition, laser parameters, and photoemission mechanisms on the electron energy spectrum and angular distribution are discussed.  P. B. Corkum, F. Krausz, Attosecond science, Nature Physics 3 (2007) 381-387.  F. Krausz, M. Ivanov, Attosecond physics, Rev. Mod. Phys. 81 (2009) 163-234.  M. F. Ciappina, et al., Attosecond physics at the nanoscale, Rep. Prog. Phys. 80 (2017) 054401.  C. Ropers, et al., Localized multiphoton emission of femtosecond electron pulses from metal nanotips, Phys. Rev. Lett. 98 (2007) 043907.  S. A. Hilbert, A. Neukirsch, C. J. G. J. Uiterwaal, H. Batelaan, Exploring temporal and rate limits of laser-induced electron emission, J. Phys. B. 42 (2009) 141001.  P. Hommelhoff, Y. Sortais, A. Aghajani-Talesh, M. A. Kasevich, Field emission tip as a nanometer source of free electron femtosecond pulses, Phys. Rev. Lett. 96 (2006) 077401.  P. Corkum, Plasma perspective on strong-field multiphoton ionization, Phys. Rev. Lett. 71 (1993) 1994-1997.  M. Lewenstein, et al., Theory of high-harmonic generation by low-frequency laser fields, Phys. Rev. A. 49 (1994) 2117-2132.  M. Krüger, M. Schenk, P. Hommelhoff, Attosecond control of electrons emitted from a nanoscale metal tip, Nature 475 (2011) 78-81.  H. S. Park, J. S. Baskin, O.-H. Kwon, A. H. Zewail, Atomic-scale imaging in real and energy space developed in ultrafast electron microscopy, Nano Letters 7 (2007) 2545-2551.  P. Hommelhoff, M. A. Kealhofer, C. Kasevich, Ultrafast electron pulses from a tungsten tip triggered by low-power femtosecond laser pulses, Phys. Rev. Lett. 97 (2006) 247402.  G. Bart, et al., Massively parallel microscopic particle-in-cell, Comput. Phys. Commun. 219 (2017) 269-285.
NL-6-27-2 / Low power nonlinear optical effects in epsilon-near-zero metasurfaces
* Laura Wynne, SUPA, University of St Andrews, United Kingdom
Andrea Di Falco, SUPA, University of St Andrews
Sebastian Schulz, SUPA, University of St Andrews
Nonlinear optical effects provide promising methods of tuning metasurface response. Here we shall demonstrate how Hilbert transforms can be utilized to measure nonlinear dephasing induced by metasurfaces. We further demonstrate that low power thermo-optic effects cause strong dephasing, promising for the future design of dynamically tunable metasurfaces.
NL-6-27-3 / Dispersion measurement with a stimulated nonlinear process
* Arash Riazi, University of Toronto, Canada
Changjia Chen, University of Toronto
Eric Y. Zhu, University of Toronto
Alexey V. Gladyshev, Fibre Optics Research Center Russian Academy of Sciences
Peter G. Kazanksy, Optoelectronics Research Centre, University of Southampton
Li Qian, University of Toronto
We demonstrate the ability to measure the second-order dispersion of a short fiber sample (< 1 m) by using a common-path nonlinear interferometer. It is the classical analog to a single-photon-level interferometer we previously demonstrated.
NL-6-27-4 / Resonant optical feedback in 1.3 micron passively mode-locked quantum dot lasers epitaxially grown on silicon
* Bozhang Dong, Institut Polytechnique de Paris, France
Xavier De Labriolle, Institut Polytechnique de Paris
Heming Huang, Institut Polytechnique de Paris
Jianan Duan, Institut Polytechnique de Paris
Songtao Liu, University of California, Santa Barbara
Justin Norman, University of California, Santa Barbara
John Bowers, University of California, Santa Barbara
Frederic Grillot, Institut Polytechnique de Paris
This work reports on the influence of the alpha–factor trend as well as the external optical feedback dynamics of an InAs/InGaAs quantum-dot mode-locked laser (QD-MLL) epitaxially grown on silicon. Our measurements revealed that the reverse bias voltage on SA contributes to enlarge the alpha-factor thus leading to a better mode-locking effect. In addition to that, we also show that the resonant external optical feedback is beneficial to reduce the RF linewidth of the epitaxial QD-MLL on silicon. This work is very promising for QD on-chip WDM sources for future large-scale silicon electronic applications requiring low power consumption as well as for high-speed photonic analog-to-digital conversion, intrachip/interchip clock distribution and recovery, and millimeter-wave signal generation for radio-over-fiber applications.
NL-6-27-5 / Studying asphaltene deposition inhibitors using surface plasmon resonance
* Raha Khosravi, Dalhousie university, Canada
Cesar Rodriguez, Dalhousie university
Vincent Sieben, Dalhousie university
We present a direct method to evaluate the effect of chemical inhibitors on the asphaltene deposition from crude oil using a surface plasmon resonance (SPR) sensor. Titration experiments were performed to induce asphaltene precipitation and deposition, which resulted in shifts of the SPR peak wavelength. SPR was effective at identifying the onset of asphaltene deposition, as well as, highlighting different temporal profiles when inhibitors were used. SPR peak wavelength can be used to characterize the refractive index of the formed deposit, and thus correlated to deposit density. Our results demonstrate that SPR techniques can be used to characterize the impact of inhibitors on the asphaltene deposition rate and composition. We believe SPR sensors will find broad applicability as a monitoring approach and/or to enable library screening methodologies.