Title: Control of femtosecond laser subwavelength fabrication on material surfaces

Biography:

Jianjun Yang has completed his PhD in optics in 1999 and spent postdotoral studies in Braunschweig technical university of Germany and Lund university of Sweden. In 2015 he joined Purdue university as a visiting professor. He is a professor in Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, China. He has published more than 80 paper in the reputed journals and holds 5 invention patents. His current research focuses on studying femtosecond laser-matter interactions, including laser ablation, micro/nano-structure fabrication, time-resolved photography, nonlinear optical process.

Abstract

The present study invesitgated the fabrication of the periodic subwavelength structures on vairous material surfaces with femtosecond laser pulses. Through using the collinear propagation of two temporally delayed femtosecond laser beams with crossed linear polarizations, we have one-step produced the regular distribution of the periodic surface structures on different materials including bulk metals and thin films without any masks. During the double-pulsed irradiation experiment, the incident first laser pulse is to modulate the optical properties of the material surface into the transient nonequibrium situations, and consequently the surface polasmon excitation behavior of the incident second laser pulse is affected. As a result, the feature aspects and the quality of the structure formation, such as the geometric profiles, the dimeniosnal size and the spatial arrangement, can be well controlled by varying the laser parameters. Moreover, it is identified that the high speed fabrication of such structures can be perfomed by adopting the line-shaped focusing of a cylindrical lens. This provide new routes for the effective design and fabrication of nanodevices for many potential applications.