scholarly journals Superposition of 2ω and Electrostatic Field Induced Terahertz Waveforms in DC-Biased Two-Color Filament

2021 ◽  
Vol 11 (24) ◽  
pp. 11888
Author(s):  
Aleksandr Ushakov ◽  
Pavel Chizhov ◽  
Irina Nikolaeva ◽  
Daniil Shipilo ◽  
Nikolay Panov ◽  
...  
Keyword(s):  
Electrostatic Field ◽  
Plasma Channel ◽  
Second Harmonic ◽  
Static Field ◽  
Local Source ◽  
Thz Radiation ◽  
Air Plasma ◽  
Optical Pump ◽  
Yield Increase ◽  
Dc Bias

Increase in conversion efficiency from a femtosecond optical pump into broadband terahertz (THz) radiation is currently an essential issue since it boosts THz source performance for medicine and security applications. An air-plasma based THz radiation from a two-color femtosecond filament is the most efficient gas-based THz emitter, with a dipole local source having a maximum on the beam propagation axis. In this work, we show the novel advancement to THz yield increase with preservation of the forwardly directed dipole radiation. The two-color THz source can be enhanced if the filament plasma channel is placed into an external electrostatic field (DC bias), which is parallel to the second harmonic polarization direction. In the experiment, we produce a plasma channel from 800-nm, ∼50-fs, 2-mJ pulse with 200 μJ of 400-nm, ∼50-fs mixed with the pump, and allocate it between the electrodes carrying 7-kV/cm static field. Time-domain measurements and 3D+time simulations of THz waveforms from the two-color DC-biased filament show that the THz emission is the superposition of the THz waveforms generated in the 800+400-nm filament without a DC-bias and in the 800-nm (without 400-nm) plasma channel biased by 7-kV/cm static field. The additivity of the two local dipole THz sources is possible if the majority of free electrons are produced by the pump pulse.

scholarly journals Design of a Pre-Bunched THz Free Electron Laser

Particles ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 267-278 ◽  
Author(s):  
Ruixuan Huang ◽  
Weiwei Li ◽  
Zhouyu Zhao ◽  
Heting Li ◽  
Jigang Wang ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Peak Power ◽  
Tuning Range ◽  
Second Harmonic ◽  
Industrial Applications ◽  
Thz Radiation ◽  
Fundamental Wave ◽  
Electron Dynamics ◽  
Main Components

Terahertz (THz) radiation has attracted much attention in new scientific and industrial applications. There has been significant recent progress in generating THz with accelerators. To investigate the collective behavior of electron dynamics, we have proposed a new high throughput material characterization system, which supplies a multiple light source. The system includes a pre-bunched THz free electron laser (FEL), which is a high-power narrow-band THz source with a wide tuning range of frequency. The physical design with the main components of the facility is introduced, and the simulation results are illustrated. Radiation of 0.5–3.0 THz is obtained by the fundamental wave of the pre-bunched beam, and radiation covering 3.0–5.0 THz is realized by second harmonic generation. As the simulation shows, intense THz radiation could be achieved in a frequency from 0.5–5.0 THz, with a peak power of several megawatts (MWs) and a bandwidth of a few percent.

scholarly journals Quasi-steady-state air plasma channel produced by a femtosecond laser pulse sequence

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Xin Lu ◽  
Shi-You Chen ◽  
Jing-Long Ma ◽  
Lei Hou ◽  
Guo-Qian Liao ◽  
...  
Keyword(s):  
Steady State ◽  
Laser Pulse ◽  
Femtosecond Laser ◽  
Femtosecond Laser Pulse ◽  
Plasma Channel ◽  
Pulse Sequence ◽  
Quasi Steady State ◽  
Air Plasma

Establishing a Quantitative Relationship Between Harmonic Signals and Damage in Interconnects

1996 ◽  
Vol 428 ◽  
Author(s):  
Qingzhe Wen ◽  
David R. Clarke
Keyword(s):  
Joule Heating ◽  
Second Harmonic ◽  
Quantitative Relationship ◽  
Third Harmonic ◽  
Resistance Method ◽  
Harmonic Signals ◽  
Ac Current ◽  
Harmonic Voltage ◽  
Dc Bias

AbstractWhen a metal conductor is driven by an AC current of frequency ω, its resistance will vary at a frequency 2ω, and a third harmonic voltage will be generated. If the conductor is also under a DC bias, a second harmonic voltage will arise as well. The magnitude of these harmonic voltages increases with damage because of nonlinear increases in the resistance caused by localized Joule heating. We use the harmonic technique to evaluate the damage in metal lines. The correlation between deliberately introduced defects of different sizes and the amplitude of the harmonic voltages has been studied experimentally. The harmonic technique shows higher damage sensitivity than the commonly used resistance method. Additionally, it has a better rejection to noise and resistance drifting.

scholarly journals Choice of Polymer Matrix for a Fast Switchable III-V Nanowire Terahertz Modulator

MRS Advances ◽  
2017 ◽  
Vol 2 (28) ◽  
pp. 1475-1480 ◽  
Author(s):  
Sarwat A. Baig ◽  
Jessica L. Boland ◽  
Djamshid A. Damry ◽  
Hoe H Tan ◽  
Chennupati Jagadish ◽  
...  
Keyword(s):  
Polymer Matrix ◽  
Modulation Depth ◽  
Areal Density ◽  
Thz Radiation ◽  
Switching Speed ◽  
Parylene C ◽  
Optical Pump ◽  
High Modulation ◽  
Thz Modulator ◽  
Probe Spectroscopy

ABSTRACTProgress in ultrafast terahertz (THz) communications has been limited due to the lack of picosecond switchable modulators with sufficient modulation depth. Gallium arsenide nanowires are ideal candidates for THz modulators as they absorb THz radiation, only when photoexcited – giving the potential for picosecend speed switching and high modulation depth. By embedding the nanowires in a polymer matrix and laminating together several nanowire–polymer films, we increase the areal density of nanowires, resulting in greater modulation of THz radiation. In this paper, we compare PDMS and Parylene C polymers for nanowire encapsulation and show that a high modulation depth is possible using Parylene C due to its thinness and its ability to be laminated. We characterize the modulator behavior and switching speed using optical pump–THz probe spectroscopy, and demonstrate a parylene–nanowire THz modulator with 13.5% modulation depth and 1ps switching speed.

scholarly journals Influence of Electric Field Coupling Model on the Simulated Performances of a GaN Based Planar Nanodevice

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
K. Y. Xu ◽  
Z. N. Wang ◽  
Y. N. Wang ◽  
J. W. Xiong ◽  
G. Wang
Keyword(s):  
Electric Field ◽  
3D Model ◽  
Second Harmonic ◽  
Strong Electric Field ◽  
Three Dimensional ◽  
Harmonic Oscillation ◽  
Two Dimensional ◽  
Dc Bias ◽  
Simulation Results ◽  
2D Model

The performances of a two-dimensional electron gas (2DEG) based planar nanodevice are studied by a two-dimensional-three-dimensional (2D-3D) combined model and an entirely 2D model. In both models, 2DEGs are depicted by 2D ensemble Monte Carlo (EMC) method. However electric field distributions in the devices are obtained by self-consistently solving 2D and 3D Poisson equations for the 2D model and the 2D-3D model, respectively. Simulation results obtained by both models are almost the same at low bias while showing distinguished differences at high bias. The 2D model predicts larger output current and slightly higher threshold voltage of Gunn oscillations. Although the fundamental frequencies of current oscillations obtained by both models are similar, the deviation of wave shape from sinusoidal waveform obtained by the 2D model is more serious than that obtained by 2D-3D model. Moreover, results obtained by the 2D model are more sensitive both to the bias conditions and to the change of device parameters. Interestingly, a look-like second harmonic oscillation has been observed at DC bias. We contribute the origin of divergences in simulation results to the different coupling path of electric field in the two models. And the second-harmonic oscillations at DC bias should be the result of the appearance of concomitant oscillations beside the channel excited by strong electric-field effects.

Failure Analysis Method of Using Laser Nano Electrostatic Field Probe Sensor (L-NEPS)

2011 ◽  
Author(s):  
Seigo Ito ◽  
Hiroko Sodeyama ◽  
Kiyoaki Takiguchi ◽  
Toru Matsumoto
Keyword(s):  
Electrostatic Field ◽  
Optical Excitation ◽  
Analysis Data ◽  
Static Field ◽  
Thermal Excitation ◽  
Analysis Method ◽  
Detection Mechanism ◽  
Contact Conditions ◽  
Failure Point ◽  
Probe Sensor

Abstract We propose in this paper to introduce the L-NEPS (Laser Nano Electro-static field Probe Sensor), which can detect the slight quasi-electrostatic field generated by optical excitation and thermal excitation occurred when laser beam irradiates on the surface and back of the Die of LSI under non-bias and non-contact conditions, as well as the method to locate the failure point with this device. This report explains the principle of quasi-electrostatic field sensing by L-NEPS and the detection mechanism, and also illustrates the effectiveness of this detection method on the basis of analysis data of two examples of LSI failures (ESD breakdown).

Application of Terahertz Spectroscopy and Imaging

2010 ◽  
Vol 5 (4) ◽  
pp. 123-129
Author(s):  
Mu Kaijun ◽  
Zhang Cunlin
Keyword(s):  
Time Domain ◽  
Quartz Crystal ◽  
Terahertz Spectroscopy ◽  
Thz Radiation ◽  
Radiation Polarization ◽  
Air Plasma ◽  
Thz Imaging ◽  
Terahertz Time Domain Spectroscopy ◽  
Security Applications ◽  
Angle Of Rotation

We examined the feasibility of Terahertz time-domain spectroscopy (THz-TDS) using a 4-mm-thick quartz crystal to extract the angle of rotation of THz radiation polarization induced by a two-color laser in air plasma. We also used the THz-TDS technique to identify explosives and melamine in mixtures. In addition, we presented a new opto-mechanical scanner for security applications using the method of passive THz imaging

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