GENERATION OF THE TERAHERZ RADIATION USING χ(3) IN SEMICONDUCTOR

1995 ◽  
Vol 04 (01) ◽  
pp. 163-189 ◽  
Author(s):  
J. B. KHURGIN
Keyword(s):  
Energy Coupling ◽  
Difference Frequency Generation ◽  
Difference Frequency ◽  
Alternative Methods ◽  
Third Order ◽  
Photogalvanic Effect ◽  
Practical Applications ◽  
The Third ◽  
Coupling Techniques ◽  
The Difference

A rigorous theory of the difference frequency mixing of two signals, one with frequency ω and the other with frequency near 2ω, in semiconductors is presented. It is shown that a lower-frequency (DC ~ 10THz) directional photocurrent and voltage are generated as a result of this nonlinear interaction. This result conclusively links the 'directional photogalvanic effect' with the third-order nonlinearity. The magnitude of the difference frequency response is evaluated as a function of frequency and the efficiency of the method is examined for various energy coupling techniques. Comparison with alternative methods for difference frequency generation using the second order nonlinearities is made and the practical applications are considered.

An analytical solution to separate P‐waves and S‐waves in VSP wavefields

Geophysics ◽  
1995 ◽  
Vol 60 (4) ◽  
pp. 955-967 ◽  
Author(s):  
Hiroshi Amano
Keyword(s):  
Analytical Solution ◽  
Formal Solution ◽  
Seismic Profile ◽  
Synthetic Seismograms ◽  
Third Order ◽  
P Waves ◽  
Practical Applications ◽  
S Waves ◽  
The Third ◽  
Z Domain

An analytical solution to separate P‐waves and S‐waves in vertical seismic profile (VSP) wavefields is derived using combinations of certain terms of the formal solution for forward VSP modeling. Some practical applications of this method to synthetic seismograms and field data are investigated and evaluated. Little wave distortion is recognized, and the weak wavefield masked by dominant wavetrains can be extracted with this method. The decomposed wavefield is expressed in the frequency‐depth (f-z) domain as a linear combination of up to the third‐order differential of traces, which is approximated by trace differences in the practical separation process. In general, five traces with single‐component data are required in this process, but the same process is implemented with only three traces in the acoustic case. Two‐trace extrapolation is applied to each edge of the data gather to enhance the accuracy of trace difference. Since the formulas are developed in the f-z domain, the influence of anelasticity can be taken into account, and the calculation is carried out fast enough with the benefit of the fast Fourier transform (FFT).

A Second-Order Three-Level Difference Scheme for a Magneto-Thermo-Elasticity Model

2014 ◽  
Vol 6 (3) ◽  
pp. 281-298 ◽  
Author(s):  
Hai-Yan Cao ◽  
Zhi-Zhong Sun ◽  
Xuan Zhao
Keyword(s):  
Difference Scheme ◽  
Hyperbolic Equations ◽  
A Priori ◽  
A Priori Estimate ◽  
Second Order ◽  
Priori Estimate ◽  
Third Order ◽  
The Third ◽  
The Difference ◽  
Second Order Convergence

AbstractThis article deals with the numerical solution to the magneto-thermo-elasticity model, which is a system of the third order partial differential equations. By introducing a new function, the model is transformed into a system of the second order generalized hyperbolic equations. A priori estimate with the conservation for the problem is established. Then a three-level finite difference scheme is derived. The unique solvability, unconditional stability and second-order convergence inL∞-norm of the difference scheme are proved. One numerical example is presented to demonstrate the accuracy and efficiency of the proposed method.

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