Influence of terahertz field on optical absorption coefficients and refractive index changes in double semi-V-shaped quantum wells

Abstract

In this paper, the refractive index changes (RICs) and optical absorption coefficients (OACs) related to an intense terahertz (THz) field and the barrier widths in double semi-V-shaped quantum wells (DSVQW) are investigated theoretically by Kramers–Henneberger approximation and the finite difference method. The numerical results show that the THz field significantly widens the DSVQW and lowers the potential barrier. The DSVQW eventually turn into triple graded quantum wells under an intense THz field. As a result, the THz field essentially changes the energy gaps and dipole matrix, which determines the strength of the OACs and RICs. Both the OACs and the RICs are nonmonotonic functions of the applied THz field and have maximum and minimum value when the THz quiver motion parameters are close to the width parameter of a potential barrier. Based on the above analysis, we conclude that a THz field can effectively improve OACs and reduce RICs. Besides, the THz quiver motion parameters needed to achieve peak positions of the OACs and minimum position of the RICs at different barrier widths are proposed, which provides the possibility of designing various infrared optics devices.