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Femtosecond Laser Double Pulses Nanofabrication on Silicon
摘要： The temporal shaping femtosecond (fs) laser is realized by dividing a fs laser pulse into two identical sub-pulses. The double-pulse fs laser can be used to effectively control the initial free electron state such as electron temperature, capacity and density, etc. to improve the surface morphology quality. In this experiment, silicon was fabricated using the double-pulse fs laser. It was found that the average diameter of ablated micro- or nanoholes decreases with the increasing pulse delay (up to 1.5 ps) under the same laser fluence and the phenomenon was explained quantitatively by the plasma model. Furthermore, nanoholes were achieved using the double-pulse fs laser, which cannot be obtained by single pulse laser, and the processing size can be reduced to below 200 nm.
关键词： femtosecond laser,silicon,plasma model,double pulses,nanofabrication
更新于2025-09-11 14:15:04
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Kinetic bandgap analysis of plasma photonic crystals
摘要： The dispersion relation of plasma and plasma-dielectric photonic multilayer structures is approached in terms of a one-dimensional Particle-in-Cell simulation. For several plasma-dielectric configurations, the system response is obtained using a pulsed excitation and a subsequent two-dimensional frequency analysis. It is first shown that the dispersion relation of a single, homogeneous plasma slab is well described by the cold-plasma model even at a low pressure of 1 Pa. The study is extended to the simulation of plasma photonic crystals with a variety of configurations based on the work of Hojo and Mase [J. Plasma Fusion Res. 80, 89 (2004)]. Considering a one-dimensional plasma photonic crystal made from alternating layers of dielectric and homogeneous plasma slabs, it is shown that the assumption of a cold-plasma description is well justified also in this case. Moreover, in this work, the results are reformatted and analyzed in a band diagram representation, in particular, based on the lattice constant a. Based on these considerations, a scaling invariant representation is presented, utilizing a generalized set of parameters. The study is completed with an exemplary comparison of three plasma-dielectric photonic crystal configurations and their corresponding band diagrams.
关键词： band diagram,Particle-in-Cell simulation,cold-plasma model,dispersion relation,plasma photonic crystals
更新于2025-09-10 09:29:36