Increasing Efficiency of Ultrafast Laser Writing Via Nonlocality of Light‐Matter Interaction

Abstract

AbstractIn ultrafast laser writing, and light‐matter interaction in general, it has been widely accepted that the higher the energy density, the stronger material changes occur, unless thermal effects are involved. Here, this belief is challenged by demonstrating that a decreased energy density—achieved through increased scanning speed and without thermal accumulation—surprisingly leads to a more significant modification of silica glass, i.e, a higher increase in the isotropic refractive index or greater birefringence of nanopore‐mediated modification. This counterintuitive phenomenon is attributed to the nonlocality of light‐matter interaction at tight focusing, where the intensity gradient of the light beam and associated diffusion of charge carriers play a critical role in increasing material modification. A tenfold increase in the writing speed of the polarization multiplexed data storage with the potential to achieve MB s‐1 using high transmission nanopore‐based modification.