<p>Investigating the effect of laser irradiation during synthesis offers a powerful method for precisely engineering the properties of nanomaterials. In this study, we synthesized carbon quantum dots (CQDs) using a thermal decomposition method under the irradiation of green and blue lasers separately and comprehensively investigated the effect of this approach on their structural, surface chemistry, and linear and nonlinear optical properties. Transmission electron microscopy (TEM) observations clearly revealed that this process leads to the synthesis of anisotropic structures, including elongated nanorods alongside spherical particles. Fourier transform infrared spectroscopy (FTIR) analysis revealed subtle changes in surface hydroxyl groups, indicating surface chemical engineering by laser. In terms of optical properties, ultraviolet–visible (UV–Vis) spectroscopy evaluation showed an increase in absorption. At the same time photoluminescence (PL) analysis indicated a significant increase in emission intensity without a substantial spectral shift after laser irradiation, highlighting improved optical performance. Notably, a new method was used to accurately determine the Cauchy scattering coefficients of CQDs, which accurately characterized the colloidal dispersion behavior. Furthermore, in exploring their nonlinear optical properties, phenomena such as inverse saturable absorption and nonlinear diffraction rings were observed, underscoring the high potential of laser-synthesized CQDs in this domain. This work not only provides an advanced approach to tune the optical properties of CQDs through laser-assisted synthesis but also introduces a unique method for determining their dispersion characteristics, paving the way for their advanced applications in nonlinear optics and photonics.</p>