Abstract: The small thermal effect in the interaction between ultrashort laser pulses and solid materials enables laser processing with micron to sub-micron resolution. Further enhancement of resolution to the nano-scale requires the understanding of ultrafast phenomena involved when a laser pulse is near and slightly above the damage threshold. In this paper, we use theoretical, simulation, and experimental methods to reveal the characteristics of laser-matter interaction in the near-threshold regime. First, we report on the reduction of feature size with two pulses that are partially overlapped in space. Features below the diffraction limit are obtained in the overlapped area on a fused silica sample, suggesting a way of resolution enhancement below 100 nm for tightly focused infrared beams. It is found that self-trapped excitons (STEs) act as energy coupler for two pulses with temporal separation longer than the lifetime of free carriers. Second, we provide theoretical support for the decoupling between resolution and optical nonlinearities recently observed in dielectrics. The question of whether such decoupling exists for other types of materials is investigated. It is proposed that the sensitivity of the near-threshold response with respect to the strength of the laser pulse is an important parameter for repeatable processing with high resolution.