In recent years, the construction of lateral heterostructures of two-dimensional (2D) monolayers of transition metal dichalcogenides (TMDC) has been attracting considerable interest due to its numerous applications in electronic and optoelectronic devices. In this work, the optical absorption coefficient of the Lateral Single Quantum Well (LSQW) based on MoS 2 / WSe 2 is analyzed theoretically. For this purpose, we rederive the absorption coefficient equation for LSQW and investigate the parameters affecting the absorption coefficient of LSQW such as the type of polarization and incident angle as well as spin–orbit coupling (SOC). Our results show the significant effect of the spin–orbit effect on the maximum value of the absorption coefficient so that by including the SOC, the values ​​of absorption coefficient increases. We surprisingly found that increasing the well width enhances the optical absorption in LSQW. Our findings and predictions might be implemented in new emerged optovalleytronic devices. Graphical abstract ( a ) Absorption coefficient as a function of the photon energy with various incident angle. ( b ) Absorption coefficient as a function of the incident angle.