Optical trapping enables efficient, noncontact manipulation of micro- and nanoscale particles; however, absorption-induced photothermal heating from the trapping beam can perturb trapping stability and measurement fidelity. Despite the ubiquity of optical tweezers in cutting-edge research, accurately quantifying their thermal effects remains difficult. Here, we employ an in-house integrated optical tweezers-Raman thermometry platform and use polystyrene (PS) particles as a model system to quantify local temperature rises in 2D and 3D trapping configurations. Our results indicate that interface traps exhibit a lower photothermal rise ($148.058\mathrm{K}{\mathrm{W}}^{-1}$) compared to 3D bulk traps ($217.556\mathrm{K}{\mathrm{W}}^{-1}$), due to efficient heat dissipation through the adjacent substrate. Despite the lower absolute temperature, the 2D configuration induces strong thermal gradients that drive Marangoni convection, resulting in a characteristic ringlike particle distribution. In contrast, bulk trapping results in higher thermal accumulation due to the thermal isolation of the liquid environment, yet maintains a more isotropic temperature field without interface-induced flow artifacts. These findings suggest that interface-constrained 2D trapping reduces thermal accumulation is valuable for precision measurements on thermally sensitive systems (e.g., biomolecules or temperature-dependent kinetics). Conversely, 3D trapping can be intentionally used to enhance optothermal actuation and microfluidic transport.

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• Microparticles
• Liquid-solid interfaces
• Optical tweezers
• Raman spectroscopy
• Thermometry