Internal stresses in arrested soft solids can be generated not only by mechanical loading but also by spatially non-uniform temperature fields, which impose incompatible thermal strains and activate coupled thermoelastic and poroelastic responses. Here we introduce an all-optical stress-and-probe protocol that combines localized near-infrared photothermal forcing with space-resolved dynamic light scattering. The setup provides (i) thermal-lensing readout of the evolving refractive-index field and (ii) photon-correlation imaging of local dynamics, complemented by speckle-based PIV to reconstruct displacement and velocity fields. We apply the method to two contrasting soft solids. In a thermoresponsive physical gel, continuous irradiation produces a slowly strengthening lensing signal that persists after the pump is switched off; refractive-index reconstruction indicates contributions beyond purely thermo-optic effects, consistent with irreversible microstructural reorganization. Concomitantly, correlation functions reveal a long-lived modification of the relaxation dynamics, supporting a scenario where constrained thermoelastic stresses imprint residual strain and drive post-excitation stress relaxation. In an ultraweak polystyrene colloidal gel with nearly temperature-independent constitutive properties, the sample deformation is driven by a buoyancy-driven convection, whose magnitude scales with the thermal expansivity of water and increases with pump power, crossing from largely elastic recovery to partial irreversibility. Overall, this optical platform enables controlled access to ultra-low, spatially distributed thermal stresses and offers a route to study stress transmission, plasticity, and cyclic photothermal fatigue in soft solids.