Label-Free Super-Resolution Microscopy By Means of Transient Absorption Saturation

n recent decades, super-resolution optical microscopy has become an attractive research topic that typically has been developed based on fluorescent labelling that becomes the essential tool for breaking diffraction-limited in biological imaging. However, deep tissue and label-free imaging remain challenging, especially for tick and highly scattering biological specimens [1]. With the development of ultrashort pulse laser sources, non-linear optical (NLO) light-matter interaction has acquired a central role in optical microscopy for label-free imaging due to efficient signal generation in the non-linear process [2]. The advantages of NLO approaches include the reduction of scattering due to the use of near-infrared radiation, which enables high penetration depth and reduces the aberrations introduced by the specimen [1]. Non-linear interaction comprises the generation of sum frequencies, high-harmonic generation