10:30 〜 11:00
▲ [20a-E214-5] [INVITED] Ultra-short laser pulses for practical 3D laser printing
キーワード：femtosecond laser fabrication, 3D laser printing, mesoscale
Ultra-short sub-1 ps laser pulses are among the most precise energy delivery tools in material processing. There is no diffusional spreading of the absorbed energy from the focal volume during the pulse. High intensity can render any dielectric material into a strongly absorbing one via the nonlinear multi-photon and avalanche ionization, which dynamically tunes the permittivity from dielectric to metallic like. The lateral and axial energy deposition can be precisely engineered and localized to the volume defined by the fraction of the laser focus for most efficient modification: ablation, polymerization, refractive index change, etc. Resolution of this material processing can reach subwavelength scale in all three dimensions. This technique delivers sub-100 nm resolution and has the unique 3D writing/printing capability among nanotechnology tools. The energy deposition and subsequent material modification has a scalar character while light polarization brings a new vectorial control of laser-induced modification. This vectorial character was demonstrated in polymerization where a more expressed polymerization took place along the electrical E-field of the linearly polarized laser beam. In this work, we introduce a new method of vectorial control of laser induced modification by applying external electrical and magnetic fields. The solid state as well as ionized ablation plasma is subjected to the applied external E- and B-fields with mobile charges experiencing the Lorenz force F = eE + e[v x B], where e is the charge, v is its velocity, E is the external electrical field, and B is the applied magnetic field.