Nonlinear refractive index changes and absorption coefficients in quantum dot induced by variable effective mass

This study explores the linear and nonlinear optical absorption coefficients (OAC) and refractive index changes (RIC) in quantum dot systems with a position-dependent variable effective mass described as $m\left(r\right)=\alpha r^{\gamma }$, where the exponent $\gamma$ controls how strongly the effective mass varies with radial distance, influencing the confinement strength and localization of carriers. Significant contributions to both linear and nonlinear OAC and RIC are observed. Our results reveal that variations in $\gamma$ modify the intersubband dipole matrix elements and energy intervals, leading to noticeable shifts in optical properties. The results show that higher $\gamma$ values shift resonance peaks toward higher energies, while changes in the confinement frequency result in abrupt shifts and peak diminutions. These insights provide a deeper understanding of the optical behaviors in the quantum systems under consideration, paving the way for designing devices with optimal efficiency.