Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session S06: Ultrafast Sources and Optics |
Hide Abstracts |
Chair: Guillaume Laurent, Auburn University Room: Grand G |
Thursday, May 31, 2018 2:00PM - 2:12PM |
S06.00001: Cavity-enhanced two-dimensional spectroscopy using higher-order modes Thomas Allison We describe methods using frequency combs and optical resonators for recording two-dimensional (2D) ultrafast spectroscopy signals with high sensitivity. By coupling multiple frequency combs to higher-order modes of one or more optical cavities, background-free, cavity-enhanced 2D spectroscopy signals are naturally generated via phase cycling. As in cavity-enhanced ultrafast transient absorption spectroscopy, the signal to noise is enhanced by a factor proportional to the cavity finesse squared, so even using cavities of modest finesse, a very high sensitivity is expected, enabling ultrafast 2D spectroscopy experiments in dilute molecular beams. [Preview Abstract] |
Thursday, May 31, 2018 2:12PM - 2:24PM |
S06.00002: Characterization of Bessel-Gauss beams for applications to high harmonic generation Adam Summers, Jan Tross, Xiaoming Yu, Xinya Wang, Shuting Lei, Carlos Trallero-Herrero Beams with a Bessel-Gaussian profile have a series of attractive properties for use with High Harmonic Generation (HHG). This includes the ability to overcome limitations typically associated with the Rayleigh range of standard Gaussian beams. In this work we demonstrate that by using a shallow angle axicon, in conjunction with a spherical lens, it is possible to generate tight focal spot sizes while maintaining a long effective focal length. The shallow focusing profile of the setup, combined with a smaller spot size can lead to extremely long phase matching lengths, while still achieving high focal intensities. Additionally, Bessel-Gauss beams develop into a so called ``donut mode'' in the far field allowing for the fundamental beam to be easily separated from the generated harmonics without the use of any filters. The relationship between ionization and harmonic generation in a Bessel-like beam is explored by scanning an Ar gas jet though the on-axis focal profile while measuring the harmonic spectrum and ionization rate in unison. These results point to the potential of using an axicon-lens combination to create a compact, table-top, high-flux XUV source.. [Preview Abstract] |
Thursday, May 31, 2018 2:24PM - 2:36PM |
S06.00003: XUV refractive optics Bernd Schuette, Lorenz Drescher, Oleg Kornilov, Tobias Witting, Geert Reitsma, Jochen Mikosch, Marc Vrakking Refractive lenses and prisms are indispensable tools used to control the properties of light beams at visible, infrared and ultraviolet wavelengths. It is therefore desirable to develop XUV refractive lenses, which is, however, hindered by the strong absorption in this spectral region. Here we demonstrate control over the refraction of XUV pulses using a gas jet with a density gradient across the XUV beam profile. In a first set of experiments, a gas-phase prism is demonstrated that leads to deflection of broadband attosecond pulse trains according to the frequency-dependent refractive index in the XUV regime. The observed deflection of XUV radiation is particularly large in the vicinity of atomic resonances. In a second set of experiments, we exploit this deflection to demonstrate a gas-phase XUV refractive lens, which allows us to focus narrowband HHG pulses. The focal length can be controlled by varying the gas type and the gas pressure. In comparison to reflective mirrors that are used to focus XUV pulses, our gas-phase lens provides further advantages, as it preserves the XUV propagation direction and is immune to damage. In combination with a Fresnel zone plate, XUV refractive lenses may be used to focus attosecond pulses to nanometer spot sizes. [Preview Abstract] |
Thursday, May 31, 2018 2:36PM - 2:48PM |
S06.00004: Compression of Yb:KGW Laser Pulses with Multi-Plate and Hollow-Core Fiber Compressors John Beetar, Shima Gholam-Mirzaei, Sean Busczek, Steven Solis, Israel Castillo, Michael Chini We investigate the spectral broadening and compression of pulses from a Yb:KGW laser amplifier separately with the use of a multi-plate continuum (MPC) and a hollow-core fiber (HCF). The pulses were compressed from 280 fs to below 20 fs using a single pass multi-stage multi-plate continuum utilizing thin fused silica windows. Similar spectra, with a Fourier transform-limited duration of 12 fs, are obtained in a 1.4 m long xenon filled hollow-core fiber. We further compare the compression factor and energy throughput of the two pulse compressors. Our results suggest that both the MPC and HCF systems can generate a broad supercontinuum capable of supporting few-cycle pulses from moderately high average power Yb:KGW laser sources. [Preview Abstract] |
Thursday, May 31, 2018 2:48PM - 3:00PM |
S06.00005: Attomicroscopy: single isolated attosecond electron pulse Mohammed Hassan In the last decades, the development of Ultrafast Electron Diffraction (UED) and Microscopy (UEM) have enabled the imaging of atomic motion in real time and space. These table-top tools opened the door for a vast range of imaging applications in different areas of science.~In UEM, the typical temporal resolution spans between few tens of picoseconds to several hundreds of femtoseconds. This resolution is insufficient to resolve the faster transient dynamics of matter lasting few tens to hundreds of femtoseconds. Here, we break the temporal resolution limits in UEM (16 times enhancement) and demonstrate the generation of intense 30-fs electron pulses by temporal optical gating approach. This technique is based on the electron-photon interaction occurs only in the presence of the laser pulse. Then, we present the feasibility of using, our recent demonstrated, optical half-cycle laser pulse (FWHM$=$380 as) to provide an attosecond gating window and generate a single isolated ``gated'' attosecond electron pulse to establish the Attomicroscopy camera. Ultimately, this attosecond camera will have the desired resolution to image the electron motion in action. [Preview Abstract] |
Thursday, May 31, 2018 3:00PM - 3:12PM |
S06.00006: Fast, GaAs, Spin-Polarized Electron Source Evan Brunkow, Eric Jones, Herman Batelaan, Timothy Gay Fast, pulsed sources of laser photo-emitted electrons from metals such as tungsten have been shown to have durations that can be comparable to the length of the laser pulse [1, 2]. Separately, continuous spin-polarized sources of electrons based on photoemission from GaAs have been developed [3]. We have now shown that we can produce fast-pulsed, spin-polarized electrons. Our initial experiments showed that when two temporally delayed pulses are incident on GaAs tips, fewer electrons are emitted as compared to the sum of the electrons emitted with each pulse individually [4]. Using a 20 keV Mott polarimeter of novel design [5], we have shown that this pulsed source is \textasciitilde 13{\%} spin polarized. However, we have evidence that the electron polarization may be dependent upon the shape of the emitting area and have started to investigate if the polarization can be increased. [1] B. Barwick \textit{et al.}, New J. Phys \textbf{9}, 142 (2007). [2] P. Hommelhoff \textit{et al.}, Phys. Rev. Lett. \textbf{96}, 077401 (2006). [3] D.T. Pierce and F. Meier, Phys. Rev. B \textbf{13}, 5484 (1976). [4] E. Brunkow \textit{et al.}, Bull. Am. Phys. Soc. \textbf{60} (2015). [5] N.B. Clayburn \textit{et al.}, Rev. Sci. Instrum. \textbf{87}, 053302 (2016). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700