Dr. Assaf Levanon Profile

Dr. Assaf Levanon

VR R&D at 3DOptix

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Laser and OPCPA expert. frequency conversion scientific .

PW and high power Lasers,

Publications (16)

Proceedings Article | 4 June 2019 Presentation + Paper

Towards direct-laser-production of relativistic surface harmonics

Elkana Porat, Assaf Levanon, Dolev Roitman, Itamar Cohen, Roei Louzon, Ishay Pomerantz

Proceedings Volume 11036, 110360I (2019) https://doi.org/10.1117/12.2520905

KEYWORDS: Near field optics, Laser systems engineering, Wavefronts, Picosecond phenomena, Plasma, Extreme ultraviolet, Mirrors, Iris, Pulsed laser operation

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The plasma mirror (PM) is an ideal model system to study relativistic optics; its geometry is simple, and its dynamics is rich and non-linear. Emphasized by high-order harmonic generation (HHG), relativistic PMs are a promising next-generation EUV source, unbounded in brightness and band-width. The applicability of these sources, however, is impeded at present because of the stringent requirement on laser intensity and temporal contrast. To-date, PM-HHG at the relativistic regime are only generated using post-compression contrast enhancement, commonly in the form of a PM-optical-switch. The complexity and low efficiency of this approach impose even stronger requirement on laser peak-power. I will present our progress towards PM-HHG in the relativistic regime using the newly commissioned 20 TW laser system at Tel-Aviv University. The laser’s architecture is based on Picosecond Optical Parametric Chirped Pulse Amplification (Ps-OPCPA) for most of the system gain, followed by a traditional Ti:Sapphire power amplifier. In Ps-OPCPA the seed pulse is amplified in a picosecond window, enhancing contrast and eliminating pre-pulses associated with the use of classic regenerative amplifiers. These result in temporal laser contrast better than 1010 on 50 picosecond time scale. Owing to this pristine contrast, we demonstrated PM-HHG directly without post-compression contrast enhancement. I will present our method for controlling the spatial phase properties of the harmonics by tailoring the focused laser intensity profile. This method is based on a beam shaping technique which employs a two-optical-paths mirror that adds a half-cycle phase to the center of the beam. A variable aperture controls the fraction of laser energy outside the phase-shifted region. By changing the aperture diameter, the focal spot profile can be manipulated from gaussian to flat-top to donut shape. Owing to strong correlation between laser intensity and HHG phase, the tailored intensity profile is mapped into the HHG spatial phase profile, changing the far field properties of the EUV beam. Our aim is to minimize the angular divergence of the generated harmonics, forming the next step towards making these sources applicable. Preliminary results towards this goal will be presented.

Proceedings Article | 24 April 2019 Paper

Cat’s cradle: a compact, 3D mounted, 90-ns optical delay-line for laser-electron acceleration

Itamar Cohen, Assaf Levanon, Dolev Roitman, Dor Shohat, Elior Urisman, Ishay Pomerantz

Proceedings Volume 11037, 1103712 (2019) https://doi.org/10.1117/12.2524941

KEYWORDS: Optical instrument design, Laser optics, Plasma, Picosecond phenomena, Mirrors, Pulsed laser operation, Mirror mounts, High power lasers

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Proceedings Article | 14 March 2018 Presentation

Pulse shaping of broadband Adiabatic SHG from a Ti:sapphire oscillator (Conference Presentation)

Assaf Levanon, Asaf Dahan, Achiya Nagler, Erga Lifshitz, Eyal Bachar, Michael Mrejen, Haim Suchowski

Proceedings Volume 10516, 105160R (2018) https://doi.org/10.1117/12.2289492

KEYWORDS: Second-harmonic generation, Frequency conversion, Pulse shaping, Oscillators, Ultrafast phenomena, Nonlinear optics, Sapphire, Ultrafast lasers, Pulsed laser operation, Laser applications

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Proceedings Article | 14 March 2018 Presentation

Ultrafast near-field imaging of excitonic waves formation and propagation in WSe2 waveguides (Conference Presentation)

Michael Mrejen, Lena Yadgarov, Uri Arieli, Assaf Levanon, Haim Suchowski

Proceedings Volume 10521, 1052107 (2018) https://doi.org/10.1117/12.2289461

KEYWORDS: Ultrafast imaging, Waveguides, Near field, Near field scanning optical microscopy, Excitons, Ultrafast phenomena, Plasmons, Polaritons, Femtosecond phenomena, Light wave propagation

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Over the recent years, van der Waals (vdW) materials, a class of materials composed of weakly bound two-dimensional (2D), atomically thin, crystalline layers, have attracted great interest due to their ability to deeply confine light and therefore significantly enhance its interaction with matter. This interaction is embodied in coupled states between light and the polarization of the media, polaritons. The most studied type of polaritons, plasmon polariton, stems from the collective oscillations of conduction electrons. These, however, suffer great losses and therefore offer limited applications. Recently, among the several other types of polaritons supported by vdW materials, the exciton polariton (EP) has stimulated intense research efforts because it can sustain both strong light– matter interactions and long-distance propagation that is necessary for applications associated with energy harvesting or information manipulation and transfer. In this context, WSe2 is of particular interest for integrated applications since it supports EP modes in the Visible- Near Infrared (VIS-NIR) spectral region at room temperature due to its tightly bond excitonic state. In the quest to unravel the underlying physics, scanning near field optical microscope (SNOM) has provided valuable insights on the nature of the steady state EP modes sustained in vdW and in WSe2 in particular. However the dynamics of the EP formation, happening in the first few hundreds of femtoseconds subsequent to light absorption, remains largely unexplored. Here we employ a unique broadband ultrafast near-field pump-probe imaging method and observe for the first time, at femtosecond and nanometric spatiotemporal scale, the dynamics of the EP waves generation and propagation in WSe2 waveguides. Our observations suggest an important interplay between the waveguide EP mode and the tip-supported plasmon. Morever, we observe an intriguing ultrafast change in the EP waveguiding properties of the WSe2 waveguides happening in the first few hundreds of femtoseconds of the EP wave formation. Our method paves the way to in-situ ultrafast coherent control of EPs modes in vdW materials.

Proceedings Article | 8 June 2015 Paper

Feasibility of Radon projection acquisition for compressive imaging in MMW region based new video rate 16x16 GDD FPA camera

Assaf Levanon, Michael Konstantinovsky, Natan Kopeika, Yitzhak Yitzhaky, A. Stern, Svetlana Turak, Amir Abramovich

Proceedings Volume 9462, 94620K (2015) https://doi.org/10.1117/12.2180367

KEYWORDS: Extremely high frequency, Radon, Sensors, Staring arrays, Mirrors, Cameras, Millimeter wave imaging, Lamps, Imaging systems, Video

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Proceedings Article | 7 October 2014 Paper

Real time three-dimensional space video rate sensors for millimeter waves imaging based very inexpensive plasma LED lamps

Assaf Levanon, Yitzhak Yitzhaky, Natan Kopeika, Daniel Rozban, Amir Abramovich

Proceedings Volume 9252, 925206 (2014) https://doi.org/10.1117/12.2065872

KEYWORDS: Sensors, Staring arrays, Extremely high frequency, Imaging systems, Lamps, Millimeter wave imaging, Plasma, Video, Mirrors, Modulation

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In recent years, much effort has been invested to develop inexpensive but sensitive Millimeter Wave (MMW) detectors that can be used in focal plane arrays (FPAs), in order to implement real time MMW imaging. Real time MMW imaging systems are required for many varied applications in many fields as homeland security, medicine, communications, military products and space technology. It is mainly because this radiation has high penetration and good navigability through dust storm, fog, heavy rain, dielectric materials, biological tissue, and diverse materials. Moreover, the atmospheric attenuation in this range of the spectrum is relatively low and the scattering is also low compared to NIR and VIS. The lack of inexpensive room temperature imaging systems makes it difficult to provide a suitable MMW system for many of the above applications. In last few years we advanced in research and development of sensors using very inexpensive (30-50 cents) Glow Discharge Detector (GDD) plasma indicator lamps as MMW detectors. This paper presents three kinds of GDD sensor based lamp Focal Plane Arrays (FPA). Those three kinds of cameras are different in the number of detectors, scanning operation, and detection method. The 1st and 2nd generations are 8 × 8 pixel array and an 18 × 2 mono-rail scanner array respectively, both of them for direct detection and limited to fixed imaging. The last designed sensor is a multiplexing frame rate of 16x16 GDD FPA. It permits real time video rate imaging of 30 frames/ sec and comprehensive 3D MMW imaging. The principle of detection in this sensor is a frequency modulated continuous wave (FMCW) system while each of the 16 GDD pixel lines is sampled simultaneously. Direct detection is also possible and can be done with a friendly user interface. This FPA sensor is built over 256 commercial GDD lamps with 3 mm diameter International Light, Inc., Peabody, MA model 527 Ne indicator lamps as pixel detectors. All three sensors are fully supported by software Graphical Unit Interface (GUI). They were tested and characterized through different kinds of optical systems for imaging applications, super resolution, and calibration methods. Capability of the 16x16 sensor is to employ a chirp radar like method to produced depth and reflectance information in the image. This enables 3-D MMW imaging in real time with video frame rate. In this work we demonstrate different kinds of optical imaging systems. Those systems have capability of 3-D imaging for short range and longer distances to at least 10-20 meters.

Proceedings Article | 7 October 2014 Paper

Detection of hidden objects using a real-time 3-D millimeter-wave imaging system

Daniel Rozban, Avihai Aharon, Assaf Levanon, Amir Abramovich, Yitzhak Yitzhaky, N. Kopeika

Proceedings Volume 9253, 925307 (2014) https://doi.org/10.1117/12.2066983

KEYWORDS: Terahertz radiation, Staring arrays, Mirrors, Imaging systems, Extremely high frequency, Sensors, Radar, Dielectrics, Metals, 3D image processing

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Proceedings Article | 9 June 2014 Paper

Large distance 3D imaging of hidden objects

Daniel Rozban, Avihai Aharon Akram, N. Kopeika, A. Abramovich, Assaf Levanon

Proceedings Volume 9078, 90780C (2014) https://doi.org/10.1117/12.2053330

KEYWORDS: Sensors, Imaging systems, Radar, Extremely high frequency, Staring arrays, Mirrors, Metals, Antennas, 3D image processing, Dielectrics

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Proceedings Article | 9 June 2014 Paper

Polarization effects on heterodyne detection and imaging using Glow Discharge Detector at millimeter wavelengths

Avihai Aharon Akram, Daniel Rozban, Niv Banay, A. Abramovich, N. Kopeika, Assaf Levanon

Proceedings Volume 9078, 90780F (2014) https://doi.org/10.1117/12.2053175

KEYWORDS: Signal detection, Heterodyning, Sensors, Polarization, Terahertz radiation, Detection theory, Plasma, Electrons, Polarizers, Neon

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Proceedings Article | 4 March 2014 Paper

Real-time 3D millimeter wave imaging based FMCW using GGD focal plane array as detectors

Assaf Levanon, Daniel Rozban, Natan Kopeika, Yitzhak Yitzhaky, Amir Abramovich

Proceedings Volume 9022, 90220R (2014) https://doi.org/10.1117/12.2041205

KEYWORDS: Sensors, Signal detection, Imaging systems, Radar, Staring arrays, Extremely high frequency, Mirrors, Heterodyning, Antennas, Dielectrics

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SPIE Journal Paper | 24 June 2013

Oversampling advances in millimeter-wave scan imaging using inexpensive neon indicator lamp detectors

Assaf Levanon, Natan Kopeika, Yitzhak Yitzhaky, Amir Abramovich, Daniel Rozban, Hezi Joseph, Avihai Aharon, Alex Belenky, Michael Gefen, Orly Yadid-Pecht

OE, Vol. 52, Issue 06, 063202, (June 2013) https://doi.org/10.1117/12.10.1117/1.OE.52.6.063202

KEYWORDS: Sensors, Lamps, Extremely high frequency, Millimeter wave imaging, Imaging systems, Scanners, Staring arrays, Mirrors, Line scan image sensors, Neon

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Proceedings Article | 31 May 2013 Paper

Heterodyne detection at 300 GHz using glow discharge detectors with efficient quasi-optical design

Avihai Aharon Akram, Daniel Rozban, Assaf Levanon , A. Abramovich, N. Kopeika

Proceedings Volume 8716, 87160T (2013) https://doi.org/10.1117/12.2015562

KEYWORDS: Signal detection, Heterodyning, Sensors, Terahertz radiation, Picosecond phenomena, Plasma, Dielectric polarization, Electrons, Dielectrics, Oscillators

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Proceedings Article | 9 May 2012 Paper

Sub-wavelength resolution of MMW imaging systems using extremely inexpensive scanning Glow Discharge Detector (GDD) double row camera

N. Kopeika, A. Abramovich, A. Levanon, A. Akram, D. Rozban, Y. Yitzhaky, O. Yadid-Pecht, A. Belenky

Proceedings Volume 8362, 83620G (2012) https://doi.org/10.1117/12.918906

KEYWORDS: Terahertz radiation, Image resolution, Diffraction, Staring arrays, Imaging systems, Sensors, Extremely high frequency, Cameras, Lamps, Millimeter wave imaging

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Proceedings Article | 13 October 2011 Paper

Low-cost THz heterodyne detection by miniature neon indicator lamp glow discharge detector

H. Joseph, N. Kopeika, A. Abramovich, A. Akram, A. Levanon, D. Rozban

Proceedings Volume 8188, 81880P (2011) https://doi.org/10.1117/12.898035

KEYWORDS: Signal detection, Sensors, Heterodyning, Terahertz radiation, Neon, Plasma, Lamps, Microwave radiation, Modulation, Ionization

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Proceedings Article | 13 October 2011 Paper

Super resolution and optical properties of THz double row array based on inexpensive Glow Discharge Detector (GDD) pixels

A. Abramovich, N. Kopeika, D. Rozban, A. Levanon, Moshe Shilemay, A. Akram, H. Joseph, O. Yadid-Pecht, A. Belenky

Proceedings Volume 8188, 81880A (2011) https://doi.org/10.1117/12.898024

KEYWORDS: Terahertz radiation, Super resolution, Sensors, Digital signal processing, Point spread functions, Staring arrays, Modulation transfer functions, Imaging systems, Metals, Lamps

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Proceedings Article | 8 September 2011 Paper

mm wave and THz imaging using very inexpensive neon-indicator lamp detector focal-plane arrays

D. Rozban, A. Levanon, A. Akram, A. Abramovich, N. Kopeika, H. Joseph, Y. Yitzthaky, A. Belenky, O. Yadid-Pecht

Proceedings Volume 8119, 81190I (2011) https://doi.org/10.1117/12.892571

KEYWORDS: Terahertz radiation, Staring arrays, Lamps, Digital signal processing, Sensors, Metals, Imaging systems, Ionization, Diffraction, Detector development

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Showing 5 of 16 publications

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