S. Varma

Jacobs (United States)

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Co-Authors

H. M. Milchberg

University of Maryland, College Park

Yu‐Hsin Chen

National Chung Hsing University

Andrew G. York

Enzo Life Sciences (United States)

Thomas M. Antonsen

University of Maryland, College Park

B. D. Layer

University of Maryland, College Park

J. P. Palastro

University of Rochester

Simona Patange

Material Measurement Laboratory

I. Alexeev

D.I. Mendeleyev All-Russian Institute for Metrology

E. W. Rosenthal

United States Naval Research Laboratory

Howard Milchberg

University of Maryland, College Park

Cooperative Institutions

University of Maryland, College Park

United States Naval Research Laboratory

Optical Sciences (United States)

Johns Hopkins University Applied Physics Laboratory

Johns Hopkins University

Naval Research Laboratory Plasma Physics Division

Lawrence Livermore National Laboratory

National Institute of Standards and Technology

University of California, Berkeley

University of Michigan–Ann Arbor

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Corrugated plasma waveguide: Slow wave structure for high intensity optical pulses

Quantum Electronics and Laser Science Conference (2007)

B. D. Layer Andrew G. York S. Varma Y. Chen H. M. Milchberg

Up to 4 cm long corrugated plasma waveguides are generated in clustered hydrogen, nitrogen, and argon gas jets. The corrugation period is as short as 70μm with relative modulation amplitudes up to ~20%.

Waveguide

Intensity

Modulation (music)

10.1109/qels.2007.4431000

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Trapping and Destruction of Long-Range High-Intensity Optical Filaments by Molecular Quantum Wakes in Air

Physical Review Letters (2008)

S. Varma Yu‐Hsin Chen H. M. Milchberg

We report the first observation of the strong effect of quantum rotational wave packets in atmospheric air on the long-range filamentary propagation of intense femtosecond laser pulses. In a pump-probe experiment, we find that the probe filament can be sucked into the pump filament's molecular quantum wake and trapped or be destroyed by it.

Intensity

10.1103/physrevlett.101.205001

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Citations (121)

Single-shot, space- and time-resolved measurement of rotational wavepacket revivals in H<inf>2</inf> and D<inf>2</inf>

Conference on Lasers and Electro-Optics (2008)

Yu‐Hsin Chen S. Varma H. M. Milchberg

Femtosecond laser induced alignment and periodic recurrences of room temperature hydrogen and deuterium molecules are measured in a single shot for the first time, using single-shot supercontinuum spectral interferometry (SSSI). The measurements are also performed in oxygen and some other common linear molecular gases. Employing time-dependent first order perturbation theory, an analytical model of rotational wavepacket revivals is derived, which shows good agreement with the experiment.

Supercontinuum

Single shot

One shot

10.1109/cleo.2008.4552397

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Citations (10)

Stimulated Emission Imaging raw data (main text)

Zenodo (CERN European Organization for Nuclear Research) (2020)

S. Varma Simona Patange Andrew G. York

Raw data for the main text of the publication found at: andrewgyork.github.io/stimulated_emission_imaging

10.5281/zenodo.3659379

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AndrewGYork/adaptive_interference_inference: Pre-print

Andrew G. York S. Varma

10.5281/zenodo.1463274

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Ultra-high Intensity Optical Slow Wave Structure and Applications

AIP conference proceedings (2007)

Andrew G. York B. D. Layer Thomas M. Antonsen S. Varma Yu‐Hsin Chen

We report the development of corrugated ‘slow wave’ plasma guiding structures and discuss their potential application to quasi‐phase‐matched direct laser acceleration of charged particles and generation of a wide spectrum of electromagnetic radiation. These structures support guided propagation at intensities up to 2×1017 W/cm2, limited by our current laser energy and side leakage. Hydrogen and argon plasma waveguides up to 1.5 cm in length with corrugation period as short as 35μm are generated in extended cryogenic cluster jet flows. Side‐imaged scattering of guided intense pulses shows evidence of periodic modulations of the laser pulse intensity.

Intensity

Radiant intensity

10.1063/1.2768847

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Periodic Index-Modulated Plasma Waveguide

B. D. Layer Andrew G. York S. Varma Y. Chen H. M. Milchberg

We demonstrate a wire-obstructed cluster flow technique for making periodically modulated plasma waveguides in hydrogen, nitrogen, and argon with sharp, stable voids as short as 50 μm with a period as small as 200 μm.

Waveguide

10.1364/cleo.2009.jfb4

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Citations (1)

The extreme nonlinear optics of gases and femtosecond optical filamentation

Physics of Plasmas (2014)

H. M. Milchberg Yu‐Hsin Chen Yu‐Hsiang Cheng N. Jhajj J. P. Palastro

Under certain conditions, powerful ultrashort laser pulses can form greatly extended, propagating filaments of concentrated high intensity in gases, leaving behind a very long trail of plasma. Such filaments can be much longer than the longitudinal scale over which a laser beam typically diverges by diffraction, with possible applications ranging from laser-guided electrical discharges to high power laser propagation in the atmosphere. Understanding in detail the microscopic processes leading to filamentation requires ultrafast measurements of the strong field nonlinear response of gas phase atoms and molecules, including absolute measurements of nonlinear laser-induced polarization and high field ionization. Such measurements enable the assessment of filamentation models and make possible the design of experiments pursuing applications. In this paper, we review filamentation in gases and some applications, and discuss results from diagnostics developed at Maryland for ultrafast measurements of laser-gas interactions.

Filamentation

10.1063/1.4896722

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Citations (29)

Enhancement of electromagnetic pulse emission from ultrashort laser pulse irradiated solid targets

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2012)

Joseph A. Miragliotta Jane W. Maclachlan Spicer Benjamin Brawley S. Varma

Ultrashort laser pulses (~100 fs duration) are known to generate charge separation in solid, liquid and gas targets through a variety of nonlinear mechanisms. This process results in the emission of a broadband electromagnetic pulse (EMP) in the microwave and terahertz (THz) regions of the electromagnetic spectrum. Possible applications of this phenomenon include remote RF and THz generation for material detection and diagnostics. We investigate the energy and spectrum of the EMP emitted from copper and glass targets irradiated by single 800 nm, 38 fs duration pulses with varying energy. The detector is two feet from the target and the detection bandwidth is 2-18 GHz. We also demonstrate our ability to enhance the emitted EMP energy from a copper target by more than an order of magnitude by irradiating the target with a 1064 nm, 14 ns duration pulse at a specific time delay relative to the ultrashort pulse. We attribute the increased optical to RF energy conversion to enhanced absorption of the ultrashort pulse by the nanosecond pulse-generated plasma at the surface of the target.

Pulse duration

Electromagnetic pulse

Nanosecond

10.1117/12.920631

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Direct measurement of the plasma density of a femtosecond laser induced-filament in air

Bulletin of the American Physical Society (2011)

Yu‐Hsin Chen S. Varma Thomas M. Antonsen Howard Milchberg

Source

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