This study provides a comprehensive investigation of the electronic band structure, dipole matrix elements, and optical susceptibility of SiNTs for arbitrary chirality and under the influence of an external magnetic field. Using a tight-binding model including integral hopping up to third-nearest neighbors, the Hamiltonian matrix elements are derived for different SiNT configurations. Results demonstrate that varying the chiral angle of nanotubes effectively tunes the peak positions and intensities of linear optical susceptibility spectra and third-order nonlinear optical susceptibility . This tunability of the optical response, combined with the ability to engineer the peak positions within the visible and near-UV ranges, makes SiNTs potentially useful for a wide range of optoelectronic devices, such as light-emitting diodes (LEDs), photodetectors, and optical modulators.
