The temporal effect of optical phase conjugation in dispersion-shifted fiber is studied numerically. Frequency chirping is induced in the conjugate pulse by the signal pulse and the pump wave through cross-phase modulation, which increases with the signal power and may distort the pulse shape when the conjugate pulse propagates in the standard fiber. It is also shown that, when the signal power...

NMR spin echo measurements of 13C in C60, 89Y in Y2O3, and 29Si in silicon are shown to defy conventional expectations when more than one pi pulse is used. Multiple pi-pulse echo trains may either freeze out or accelerate the decay of the signal, depending on the pi-pulse phase. Average Hamiltonian theory, combined with exact quantum calculations, reveals an intrinsic cause for these coherent p...

The temporal effect of optical phase conjugation in a semiconductor laser amplifier is studied numerically. The conjugate pulse has distortion and frequency chirping owing to the carrier depletion induced by the signal pulse. Both the pulse-shape distortion and frequency chirping are enhanced as the signal power and the injection current increase. We can reduce these two effects by increasing t...

We propose an ultrafast pulse shaping method by modulating the pulse phase and amplitude by the electro-optic effect and Bragg diffraction in the aperiodically optical superlattice. Linear-chirped periodically poled lithium niobate is used. The input pulse can be shaped, for example, by compressing it through the extraordinary refractive index change of the crystal by applying and changing the ...

-Electrical discharge machining (EDM) process, at present is still an experience process, wherein selected parameters are often far from the optimum, and at the same time selecting optimization parameters is costly and time consuming. In this paper cryogenic treatment is used for increasing the material removal rate and lowering the tool wear rate. cryogenic treatment is a process of keeping th...

The micro all-electric vehicle pertaining to this study is rear-driven, with motors in the left and right rear wheels. The motors are brushless dc (BLDC) using Hall effect sensors with a trapezoidal back-electromotive force. The control system is developed by using a digital signal processor. To thoroughly utilize the fast torque generation feature of BLDC motors, direct torque control (DTC) is...

An effect of the dynamic gain saturation on chirped-pulse oscillator was investigated. It was found, that the dynamic gain saturation causes strong perturbations of the pulse front that destabilizes an oscillator. As a result, the chirped-pulse exists only within some limited range of dispersions and there is a limit of energy growth for a given resonator period.

In this paper, we report, for the first time, that by modulating pump beam to suppress ASE effect we realized ultra-low repetition rate output in an all fiber based Er:Yb codoped master oscillator power amplifiers (MOPA) system. Combined with pulse shaping technology, pulses with up to 205 µJ pulse energy and 200 ns pulse duration were obtained at Hz level.

The pulse shape deformation of 80 ps Gaussian input transmitted through a Fabry-P6rot has been determined experimentally and theoretically as a function of the mirror spacing. The effect of mirror surface imperfections is discussed and it is shown that for not too large imperfections there is a strong influence on the transmitted pulse energy whereas the transmitted pulse shape remains almost u...

Laser pulse heating of solid surface and entropy generation during the heating process are considered. Time exponentially decaying pulse is accommodated in the analysis and the laser pulse parameter (b1/b2) resulting in minimum entropy generation rate is computed. Analytical solutions for temperature rise are presented and volumetric entropy generation rate is formulated. Two laser pulses resul...