Extracavity-generated femtosecond near-UV vortex beams and their use for filament inscription in bulk polymethylpentene
This study demonstrated that a femtosecond near-ultraviolet (NUV) vortex beam—generated by first modulating a near-infrared (NIR) laser beam with a liquid crystal spatial light modulator (SLM) and then converting the modulated NIR beam into the NUV via second-harmonic generation (SHG)—enabled in situ direct modificatio...