Single-shot ultrafast terahertz near-field microscopy

Precise imaging of transient events, encompassing both the spatial and temporal dimensions, is crucial for understanding complex interactions within materials and biological structures at the microscopic scale. Although terahertz radiation has shown its benefits for real-time imaging in optically opaque scenarios, capturing ultrafast dynamics at microscales in a single shot using terahertz full-field imaging remains in its infancy. Here, we present a single-shot ultrafast terahertz near-field microscope capable of acquiring multiple frames of a transient scene with simultaneous sub-wavelength spatial and sub-picosecond temporal resolution. Our approach leverages the electro-optic sampling technique for terahertz near-field detection, operated in a single-shot manner, with a judiciously designed train of spatially modulated and temporally delayed probe pulses. This enables us to effectively encode the terahertz-captured microscopic dynamics at different time instants into a single superimposed optical image, which can then be decoded computationally in Fourier space. Our technique opens promising, largely unexplored pathways for studying ultrafast non-repeatable or irreversible processes at microscales, especially in materials or environments that are inaccessible with conventional optical frequencies.