Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session U4: Novel Ultrafast and Laser Technology |
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Chair: Carlos Trallero, Kansas State University Room: Union DE |
Friday, June 12, 2015 10:30AM - 10:42AM |
U4.00001: Intense terahertz generation by different frequency of super-Gaussian lasers in presence of transverse magnetic field Anil Kumar Malik We propose a mechanism of high intensity terahertz (THz) radiation generation by photo-mixing of super-Gaussian lasers with frequencies$\omega _{1} $, $\omega_{2} $ and wave numbers $k_{1} ,k_{2} $ (profile index p \textgreater 2) in a corrugated plasma under the effect of static magnetic field $B_{0} \hat{{z}}$. The scheme is based on a strong nonlinear ponderomotive force offered by lasers fields to the plasma electrons at frequency ${\omega }'=\omega_{1} -\omega_{2} $ and wave number ${k}'=k_{1} -k_{2} $. The ponderomotive force offers nonlinear transverse plasma current. This controllable current produces the focused radiation of tunable frequency and power along with a remarkable efficiency of the scheme as $\sim $0.02. [Preview Abstract] |
Friday, June 12, 2015 10:42AM - 10:54AM |
U4.00002: A carrier-envelope-phase stabilized terawatt class laser at 1~kHz with a wavelength tunable option C.A. Trallero, B. Langdon, J. Garlick, X. Ren, D.J. Wilson, A.M. Summers, S. Zigo, M.F. Kling, S. Lei, C.G. Elles, E.D. Poliakoff, K.D. Carnes, V. Kumarappan, I. Ben-Itzhak We demonstrate a chirped-pulse-amplified Ti:Sapphire laser system operating at 1~kHz, with 20~mJ pulse energy, 26~femtosecond pulse duration (0.77~terawatt), and excellent long term carrier-envelope-phase (CEP) stability. A new vibrational damping technique is implemented to significantly reduce vibrational noise on both the laser stretcher and compressor, thus enabling a single-shot CEP noise value of 250~mrad RMS over 1~hour and 300~mrad RMS over 9~hours. This is, to the best of our knowledge, the best long term CEP noise ever reported for any terawatt class laser. This laser is also used to pump a white-light-seeded optical parametric amplifier, producing 6~mJ of total energy in the signal and idler. Due to preservation of the CEP in the white-light generated signal and passive CEP stability in the idler, this laser system promises synthesized laser pulses spanning multi-octaves of bandwidth at an unprecedented energy scale. [Preview Abstract] |
Friday, June 12, 2015 10:54AM - 11:06AM |
U4.00003: Few cycle Mid-IR OPCPA laser for generating isolated attosecond pulses Jie Li, Yanchun Yin, Xiaoming Ren, Zhao Kun, Wu Yi, Eric Cunningham, Zenghu Chang A Mid-IR OPCPA laser operating at 1 kHz is being developed for generating isolated attosecond pulses in the water window. Strong seed pulses with 500 nJ energy from 1.1 $\mu$m to 2.5 $\mu$m were produced by intro-pulse different frequency generation driven by white-light pulses from a gas filled hollow-core fiber, which is critical for suppressing superfluorescence in the optical parametric amplifiers. Broadband amplification was achieved by phase matching each signal frequency with its optimized pump frequency inside BIBO crystals. [Preview Abstract] |
Friday, June 12, 2015 11:06AM - 11:18AM |
U4.00004: Variable Thickness Liquid Crystal Films for High Repetition Rate Laser Applications Patrick Poole, Christopher Willis, Ginevra Cochran, Randall Hanna, C. David Andereck, Douglass Schumacher The presentation of a clean target or target substrate at high repetition rates is of importance to a number of photoelectron spectroscopy and free electron laser applications, often in high vacuum environments. Additionally, high intensity laser facilities are approaching the 10 Hz shot rate at petawatt powers, but are currently unable to insert targets at these rates. We have developed liquid crystal films to address this need for high rep rate targets while preserving the planar geometry advantageous to many applications. The molecular ordering of liquid crystal is variable with temperature and can be manipulated to form a layered thin film. In this way temperature and volume control can be used to vary film thickness in vacuo and on-demand between 10 nm and over 10 $\mu$m. These techniques were previously applied to a single-shot ion acceleration experiment in P. L. Poole Phys. Plasmas \textbf{21}, 063109 (2014), where target thickness critically determines the physics of the acceleration. Here we present an automatic film formation device that utilizes a linear sliding rail to form liquid crystal films within the aforementioned range at rates up to 0.1 Hz. The design ensures film formation location within 2 $\mu$m RMS, well within the Rayleigh range of even short f-number systems. Details of liquid crystal films and this target formation device will be shown as well as recent experimental data from the Scarlet laser facility at OSU. [Preview Abstract] |
(Author Not Attending)
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U4.00005: ELI-ALPS -- Prospects of doing attosecond physics at world's first laser-driven user facility Predrag Ranitovic ELI-ALPS, a laser-driven attosecond X-Ray user facility, would provide a wide range of state-of-the-art laser and attosecond light sources, and experimental endstations that would serve a broad network of user communities covering fields such as \textit{AMO Physics}, \textit{Condensed Matter} \textit{Physics}, \textit{Materials Sciences, and Physical Chemistry}. In this talk, we will present the scientific roadmap of ELI-ALPS, and give an overview of the laser and attoscond pulse specs, and endstations made available for users in near future. In particular, we will discuss the opportunities for doing AMO physics by utilizing a wide range of attosecond experimental techniques and brilliant, energetic and high-flux light-sources. [Preview Abstract] |
Friday, June 12, 2015 11:30AM - 11:42AM |
U4.00006: Measuring the intensity of intense laser pulses at the few-percent level Stefan Zigo, Yujun Wang, Jan Tross, Peyman Feizollah, Ben Berry, Yubaraj Malakar, Rajesh Kushawaha, Vinod Kumarappan, Artem Rudenko, Itzik Ben-Itzhak, Brett Esry, Carlos Trallero-Herrero Strong-field measurements are often frustratingly difficult to reproduce quantitatively either through further experiment or through comparison with theory. One of the reasons for this difficulty is the large uncertainty that typically accompanies the measurement of an intense laser pulse's peak intensity, which often falls in the tens of percent range. Despite many attempts, there remains no readily accessible way to do better. And, since most strong-field processes of interest are highly nonlinear, small changes in intensity can translate to large changes in the outcome. The trick, of course, is to use this sensitivity as the measurement---but one needs a reliable calibration curve to compare with. We aim to develop a technique based on the total ionization yield of argon that can be easily implemented yet provides intensity measurements at the few-percent level through comparison with carefully calibrated solutions of the time-dependent Schrodinger equation. [Preview Abstract] |
Friday, June 12, 2015 11:42AM - 11:54AM |
U4.00007: Buckling transition in an optomechanical system Haitan Xu, Utku Kemiktarak, John Lawall, Jacob Taylor We analytically study and experimentally realize the buckling transition in an optomechanical system with a membrane in the middle of a Fabry-Perot cavity. Pumping the system lasers couples the optical and mechanical modes, which changes the effective potential of the membrane. Specifically, we find that a harmonic potential, at low power, develops into a double-well potential with increasing optical power, leading to a buckling transition for the membrane-in-the-middle system. [Preview Abstract] |
Friday, June 12, 2015 11:54AM - 12:06PM |
U4.00008: Laser Activated Streak Camera for Measurement of Electron Pulses with Femtosecond Resolution Omid Zandi, Alice DeSimone, Kyle Wilkin, Jie Yang, Martin Centurion The duration of femtosecond electron pulses used in time-resolved diffraction and microscopy experiments is challenging to measure in-situ. To overcome this problem, we have fabricated a streak camera that uses the time-varying electric field of a discharging parallel plate capacitor. The capacitor is discharged using a laser-activated GaAs photoswitch, resulting in a damped oscillation of the electric field. The delay time between the laser pulse and electron pulse is set so that the front and back halves of the bunch encounter opposite electric fields of the capacitor and are deflected in opposite directions. Thus, the electron bunch appears streaked on the detector with a length proportional to its duration. The temporal resolution of the streak camera is proportional to the maximum value of the electric field and the frequency of the discharge oscillation. The capacitor is charged by high voltage short pulses to achieve a high electric field and prevent breakdown. We have achieved an oscillation frequency in the GHz range by reducing the circuit size and hence its inductance. The camera was used to measure 100 keV electron pulses with up to a million electrons that are compressed transversely by magnetic lenses and longitudinally by an RF cavity. [Preview Abstract] |
Friday, June 12, 2015 12:06PM - 12:18PM |
U4.00009: Coincidence electron/ion imaging with a fast frame camera Wen Li, Suk Kyoung Lee, Yun Fei Lin, Steven Lingenfelter, Alexander Winney, Lin Fan A new time- and position- sensitive particle detection system based on a fast frame CMOS camera is developed for coincidence electron/ion imaging. The system is composed of three major components: a conventional microchannel plate (MCP)/phosphor screen electron/ion imager, a fast frame CMOS camera and a high-speed digitizer. The system collects the positional information of ions/electrons from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of MCPs processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of electron/ion spots on each camera frame with the peak heights on the corresponding time-of-flight spectrum. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide. We further show that a time resolution of 30 ps can be achieved when measuring electron TOF spectrum and this enables the new system to achieve a good energy resolution along the TOF axis. [Preview Abstract] |
Friday, June 12, 2015 12:18PM - 12:30PM |
U4.00010: Extreme rotational excitation with long sequences of intense femtosecond pulses Martin Bitter, Valery Milner We present an experimental approach to rotational excitation of molecules capable of creating ultra-broad rotational wave packets inaccessible with other methods, including the technique of an optical centrifuge. Our approach is based on an impulsive excitation by a long sequence of more than 20 laser pulses with peak intensities within each pulse exceeding $10^{13}$ W/cm$^{2}$. The method overcomes the three obstacles on the way towards extreme rotational excitation: (i) the strong-field effects associated with a single-pulse scheme, (ii) the centrifugal distortion and Anderson localization in a multi-pulse approach, and (iii) the bandwidth limitation of an optical centrifuge. In oxygen, we demonstrate the ability to populate rotational states with an angular momentum $N \approx 250\hbar$, more than twice higher than previously achieved with the centrifuge. Precise timing of the pulses and their spectral broadening due to molecular phase modulation, essential to this technique, are demonstrated and discussed. [Preview Abstract] |
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