Quadratic electro-optic effects and electro-absorption process in semiconductor carbon nanotubes

The quadratic electronic-optic effects (QEOE) and electro-absorption process (EA) are calculated and analyzed theoretically for a bundle of semiconductor carbon nanotubes (CNs) with two-band approximation. The third-order susceptibility dispersion behaviors of direct current (DC) are obtained and there are several new features, which are important for their potential application as photonic devices. Meanwhile, it is found that for two types of semiconductor carbon nanotubes the nonlinear susceptibilities χ(3)χ(3) are substantially different and they both strongly depend on nanotubes geometry and considerably increase with the radius of the carbon nanotubes. For instance, View the MathML sourceχDC(3) of (22, 0) CN is larger than that of (23, 0), but the diameter of the former is smaller than that of the latter. In addition, it is also found that the resonant peak position in the dispersion of View the MathML sourceχDC(3) is related to the effect of the mixing between π and σ states.