Skin treatment device for multiphoton ionization-based skin treatment

A skin treatment device for generating a multiphoton ionization process in a target position in skin tissue, the skin treatment device comprising:

• a laser source configured and constructed for generating a treatment laser beam,
• an optical system configured and constructed such that, in use, the treatment laser beam is focused into a focal spot in the target position in the skin tissue,
• a plasma unit configured and constructed for generating a plasma such that, in use, at least a portion of the plasma penetrates the skin tissue and generates at least one free electron in the target position in the skin tissue, and
• a control unit configured and constructed for controlling the laser source and the plasma unit,
• characterized in that the laser source and the optical system are configured and constructed such that, in use, a power density (W/cm2) of the treatment laser beam) in the focal spot in the skin tissue is below a first power density threshold (Ith1) for the skin tissue, above which a free electron is generated in the skin tissue by absorption of photons present in the treatment laser beam, and the power density (W/cm2) of the treatment laser beam in the focal spot is above a second power density threshold (Ith2) for the skin tissue, above which an avalanche ionization process is generated in the skin tissue by Inverse Bremsstrahlung absorption by a free electron of photons present in the treatment laser beam.