Modifying optical properties of three-level V-type atomic medium by varying external magnetic field

Optical properties including absorption, dispersion, group index, Kerr nonlinearity, and optical bistability of a three-level V-type atomic medium have modified by varying an external magnetic field. By changing the magnitude or the sign of the external magnetic field, the transparency window with normal dispersion transfers to the enhanced absorption with anomalous dispersion at the line center, and hence the light propagation switches between subluminal and superluminal modes. The magnitude and the sign of the Kerr nonlinearity are controlled with the strength and the sign of the magnetic field. As a consequence, the behaviors of optical bistability are also made to appear or disappear when switching on/off the magnetic field. Moreover, the threshold intensity and width of optical bistability are also changed by the magnetic field and the coupling field. The results can be used to control the working characteristics of applied devices and study the related effects.