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An asymmetric quantum well (AQW) is designed to emit terahertz (THz) waves by using difference frequency generation (DFG) with the structure of GaAs/Al0:2Ga0:8As/Al0:5Ga0:5As. The characteristics of absorption coefficients are analysed under the parabolic and non-parabolic energy-band conditions in detail. We find that the absorption coefficients vary with the two pump optical intensities, and they reach the maxima when the pump wavelengths are given as p1 = 9:70 m and p2 = 10:64 m, respectively. Compared with non-parabolic conditions, the total absorption coefficient under parabolic conditions shows a blue shift, which is due to the increase in the energy difference between the ground and excited states. By adjusting the two pump optical intensities, the wave vector phase-matching condition inside the AQW is satisfied. [ABSTRACT FROM AUTHOR]

This paper presents a set of equations describing the terahertz generation and electro-optic detection based on optical rectification in zincblende crystals. The dependence of terahertz emission efficiency on the polarization of incident beam and crystal-orientation is discussed. For the experimental setup with a transceiver which transmits and detects terahertz radiation in the same crystal, we have demonstrated the optimal combination of both parameters above to optimize the working efficiency. Equations supplied in this paper are valid for zincblende crystals with arbitrary crystalorientation and every possible polarization of an incident beam, which are of great significance for the optimization of a system. [ABSTRACT FROM AUTHOR]