Evolution of phase difference and absolute phase of interacting waves under SHG of high intensive femtosecond pulse

2017 ◽  
Author(s):  
Vyacheslav A. Trofimov ◽  
Dmitry M. Kharitonov ◽  
Mikhail V. Fedotov
Keyword(s):  
Phase Difference ◽  
Femtosecond Pulse ◽  
Absolute Phase

scholarly journals Linear and nonlinear absolute phase effects in interactions of ulrashort laser pulses with a metal nano-layer or with a thin plasma layer

2007 ◽  
Vol 25 (3) ◽  
pp. 379-390 ◽  
Author(s):  
S. Varró
Keyword(s):  
Laser Pulse ◽  
Phase Difference ◽  
Plasma Layer ◽  
Thin Foil ◽  
Laser Pulses ◽  
Thomson Scattering ◽  
Carrier Envelope Phase ◽  
Absolute Phase ◽  
High Intensity Laser ◽  
Order Of Magnitude

It has been shown that in the scattered radiation, generated by an ultrashort laser pulse impinging on a metal nano-layer, non-oscillatory wakefields appears with a definite sign. The magnitude of these wakefields is proportional to the incoming field strength, and the definite sign of them is governed by the cosine of the carrier-envelope phase difference of the incoming pulse. When we let such a Wakefield excite the electrons of a secondary target (say an electron beam, a metal surface or a gas jet), we can obtain 100 percent modulation in the electron signal in a given direction. This scheme can serve as a basis for the construction of a robust linear carrier-envelope phase difference meter. At relativistic laser intensities, the target is considered as a plasma layer in vacuum produced from a thin foil by a prepulse, which is followed by the main high-intensity laser pulse. The nonlinearities stemming from the relativistic kinematics lead to the appearance of higher-order harmonics in the scattered spectra. In general, the harmonic peaks are downshifted due to the presence of an intensity-dependent factor. This phenomenon is analogous to the famous intensity-dependent frequency shift in the nonlinear Thomson scattering on a single electron. In our analysis, an attention has also been paid to the role of the carrier-envelope phase difference of the incoming few-cycle laser pulse. It is also shown that the spectrum has a long tail where the heights of the peaks vary practically within one order of magnitude forming a quasi-continuum. Fourier synthesizing the components from this plateau region attosecond pulses has obtained.

A Novel Coordinate Rotation Digital Computer Method for Energy and Latency Saving by Trigonometric Operations Spatial Locality Principle

2019 ◽  
Vol 15 (4) ◽  
pp. 338-350
Author(s):  
Giuseppe Visalli
Keyword(s):  
Total Energy ◽  
Phase Difference ◽  
Energy Budget ◽  
General Purpose ◽  
Vlsi Architectures ◽  
Spatial Locality ◽  
Cycle Simulation ◽  
Absolute Phase ◽  
Significant Area ◽  
Locality Principle

In this work, we propose an approximate and energy-efficient CORDIC method, based on a trigonometric function spatial locality principle derived from benchmarks profiling. Successive sine/cosine computation requests cover more than 50% when the absolute phase difference is at most ten degrees. Consequently, this property suggests an optimized circuit implementation, both iterative or a succession of microrotation modules, where the last CORDIC requires fewer iterations, reducing the latency and the total energy budget at the same precision of two separate and independent instances. Thus, this simple design strategy allows significant area and energy dissipation in general-purpose VLSI architectures, but it introduces also dramatically optimizations in applicationspecific embedded systems used in the area of signal processing and radio frequency communication. In this contribution, we introduce a method, the hardware overhead and the energy budget per single cycle. Simulation results show the total energy saving in considered benchmarks is 40% in pipelined and iterative general purposes CORDIC. Furthermore, our application-specific systems (fast Fourier transform and digital oscillators for radiofrequency down conversions) show remarkable cycle savings when the successive sine/cosine computation requests are more than 70%. Finally, in this work, we extend the proposed approach to whichever phase difference less than 26.56° , as a variable for the second CORDIC number of angle rotations.

An Absolute Phase Estimation Method for Interferometry Imagery

2019 ◽  
Vol 1 (2) ◽  
pp. 14-19
Author(s):  
Sui Ping Lee ◽  
Yee Kit Chan ◽  
Tien Sze Lim
Keyword(s):  
Noise Suppression ◽  
Estimation Method ◽  
Phase Image ◽  
Phase Estimation ◽  
Phase Reconstruction ◽  
Estimation Algorithms ◽  
Absolute Phase ◽  
Filtering Rate ◽  
Interferometric Phase ◽  
Image Performance

Accurate interpretation of interferometric image requires an extremely challenging task based on actual phase reconstruction for incomplete noise observation. In spite of the establishment of comprehensive solutions, until now, a guaranteed means of solution method is yet to exist. The initially observed interferometric image is formed by 2π-periodic phase image that wrapped within (-π, π]. Such inverse problem is further corrupted by noise distortion and leads to the degradation of interferometric image. In order to overcome this, an effective algorithm that enables noise suppression and absolute phase reconstruction of interferometric phase image is proposed. The proposed method incorporates an improved order statistical filter that is able to adjust or vary on its filtering rate by adapting to phase noise level of relevant interferometric image. Performance of proposed method is evaluated and compared with other existing phase estimation algorithms. The comparison is based on a series of computer simulated and real interferometric data images. The experiment results illustrate the effectiveness and competency of the proposed method.

What Is The Best Distance And Phase Difference Between The Elements Of Linear Antnna Array

2017 ◽  
pp. 1
Author(s):  
Asma M. N. El Ferjani ◽  
Ahmed S. El Barsha ◽  
AlZaroog Saleh Abdulali
Keyword(s):  
Phase Difference

Characterization of Flood Waves by Rating Curves

1997 ◽  
Vol 28 (1) ◽  
pp. 51-64 ◽  
Author(s):  
S.K. Mishra ◽  
M.K. Jain ◽  
S.M. Seth
Keyword(s):  
Phase Difference ◽  
Central India ◽  
Wave Number ◽  
Wave Characteristics ◽  
Travel Wave ◽  
Frame Work ◽  
Rating Curves ◽  
Exact Relationship ◽  
Flood Waves

The flood waves are characterized within the frame-work of loop (or hysteresis) of rating curves. The National Weather Service's Dam Break Flood Forecasting Model is used to generate the flood waves in the downstream valley of the Bargi dam located in Central India. The quantified hystereses, η, of non-dimensional rating curves are related with the corresponding flood wave characteristics, viz., speed of travel, wave number, phase difference, and attenuation. The analysis has led to the development of an exact relationship between η and phase difference. Using the concept of wave zoning, the better performance of the hysteresis based criteria compared with the available criteria is verified using Convex and Muskingum-Cunge routing in the wave zones. η limits are specified for the applicability of these simplified routing models. Furthermore, the envisaged applications of the based analysis are introduced.

scholarly journals Femtosecond Pulse Temporal Overlap Estimation and Adjustment in SSFS-Based CARS System

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 131317-131325 ◽  
Author(s):  
Yongning Zhang ◽  
Junfeng Jiang ◽  
Shuang Wang ◽  
Kun Liu ◽  
Zhe Ma ◽  
...  
Keyword(s):  
Femtosecond Pulse ◽  
Temporal Overlap
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