Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session U9: Invited Session: Ultrafast Techniques and Light SourcesInvited
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Chair: Kenneth Knappenberger, Florida State University Room: 556AB |
Friday, May 27, 2016 10:30AM - 11:00AM |
U9.00001: Cavity-Enhanced Ultrafast Spectroscopy Invited Speaker: Thomas Allison Ultrafast optical spectroscopy methods, such as transient absorption spectroscopy and 2D-spectroscopy, are widely used across many disciplines. However, these techniques are typically restricted to optically thick samples, such as solids and liquid solutions. Using a frequency comb laser and optical cavities, we present a new technique for performing ultrafast optical spectroscopy with high sensitivity, enabling work in dilute gas-phase molecular beams. Resonantly enhancing the probe pulses, we demonstrate transient absorption measurements with a detection limit of $\Delta$OD = $2 \times 10^{-10}$ ($1 \times 10^{-9}/\sqrt{\mbox{Hz}}$). Resonantly enhancing the pump pulses allows us to produce a high excitation fraction at high repetition-rate, so that signals can be recorded from samples with optical densities as low as OD $\approx 10^{-8}$, or column densities $<$ $10^{10}$ molecules/cm$^2$. To our knowledge, this represents a 5,000-fold improvement of the state-of-the-art. [Preview Abstract] |
Friday, May 27, 2016 11:00AM - 11:30AM |
U9.00002: Isolated attosecond soft X-rays and water window XAFS Invited Speaker: Jens Biegert We demonstrate generation of isolated attosecond soft X-ray pulses with duration less than 350 as at the carbon K-edge at 284 eV. This reproducible and CEP stable attosecond soft X-ray continuum covers the entire water window from 200 eV to 550 eV with a flux of 7.3x10$^{7}$ photons/s and corresponds to a pulse energy of 2.9 pJ. We demonstrate the utility of our table-top source through soft X-ray near-edge fine-structure spectroscopy at K-shell absorption edges in condensed matter and retrieve the specific absorption features corresponding to the binding orbitals. We believe that these results herald attosecond material science by bridging the gap between ultrafast temporal resolution and element specific probing at the fundamental absorption edges of matter. [Preview Abstract] |
Friday, May 27, 2016 11:30AM - 12:00PM |
U9.00003: Frequency domain nonlinear optics. Invited Speaker: Francois Legare The universal dilemma of gain narrowing occurring in fs amplifiers prevents ultra-high power lasers from delivering few-cycle pulses. This problem is overcome by a new amplification concept: Frequency domain Optical Parametric Amplification -- FOPA [1]. It enables simultaneous up-scaling of peak power and amplified spectral bandwidth and can be performed at any wavelength range of conventional amplification schemes, however, with the capability to amplify single cycles of light. The key idea for amplification of octave-spanning spectra without loss of spectral bandwidth is to amplify the broad spectrum "slice by slice" in the frequency domain, i.e. in the Fourier plane of a \textit{4f}-setup. The striking advantages of this scheme, are its capability to amplify (more than) one octave of bandwidth without shorting the corresponding pulse duration. This is because ultrabroadband phase matching is not defined by the properties of the nonlinear crystal employed but the number of crystals employed. In the same manner, to increase the output energy one simply has to increase the spectral extension in the Fourier plane and to add one more crystal. Thus, increasing pulse energy and shortening its duration accompany each other. A proof of principle experiment was carried out at ALLS on the sub-two cycle IR beam line and yielded record breaking performance in the field of few-cycle IR lasers. 100$\mu $J two-cycle pulses from a hollow core fibre compression setup were amplified to 1.43mJ without distorting spatial or temporal properties. Pulse duration at the input of FOPA and after FOPA remains the same. Recently, we have started upgrading this system to be pumped by 250 mJ to reach 40 mJ two-cycle IR few-cycle pulses and latest results will be presented at the conference. Furthermore, the extension of the concept of FOPA to other nonlinear optical processes will be discussed. [1] B. E. Schmidt et al. \textit{Nature Commun.} \textbf{5}, 3643 (2014). [Preview Abstract] |
Friday, May 27, 2016 12:00PM - 12:30PM |
U9.00004: Photon Processing via Four-Wave Mixing Invited Speaker: Alexander Gaeta Quantum frequency conversion is the process by which the wavelength of a light beam is converted to another wavelength while still maintaining its quantum state. Until recently, achieving this process with high conversion efficiency and low noise had been achieved only with second-order nonlinear materials. Here, we describe our recent research that utilizes four-wave mixing in an optical fiber to perform ultralow noise quantum frequency conversion with efficiencies exceeding 90{\%}. We also show how this nonlinear process can be used to realize other quantum phenomena including creating a single-photon Ramsey interferometer and temporally magnifying or compressing single-photon pulses. The latter allows us to perform photon counting with a temporal resolution better than 2 ps. [Preview Abstract] |
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