Abstract: As a non-invasive method, laser biological modulation technology can manipulate specific molecular processes and functions of cells or organisms at both in vitro and in vivo levels through different mechanisms. This review analyzes the light absorption spectrum of distinct intracellular endogenous photosensitive molecules, elaborates on the main physical mechanisms of laser-tissue interaction, including the photothermal effect and photochemical effect by linear absorption, as well as the multiphoton excitation and weak ionization effect driven by high photon density. This review discusses the possibility of direct specific interactions between laser and different molecules in cells. Based on this, the regulatory mechanisms, applications, technical characteristics and limitations of low-level laser therapy and femtosecond-laser specific modulation technology are derived. This paper further analyzes the biological modulation strategies, technical advantages and limitations of optogenetics and optical uncaging technology, and conducts a detailed comparison of these four technologies. Finally, aiming at the current challenges such as penetration depth limitations caused by tissue scattering, lack of molecular specificity and poor biocompatibility, the causes and potential solutions are specifically elaborated.
Key words: laser modulation; photobiomodulation; optogenetics; photo-uncaging; femtosecond laser
（Acta Laser Biology Sinica, 2026, 35(2): 097-110）