Flexible Gray‐Scale Surface Patterning Through Spatiotemporal‐Interference‐Based Femtosecond Laser Shaping

Abstract

The function of a laser‐shaped material depends on the geometrical morphology of its laser‐induced surface structures, which is mainly determined by the spatial intensity distribution of the laser. However, conventional patterning methods based on laser shaping techniques have shortcomings in efficiency or flexibility. A novel patterning method is developed in the present study for mask‐free and flexible fabrication of surface structures through a time‐saving spatiotemporal‐interference‐based femtosecond laser shaping technique that is based on a Michelson interferometer. The phase‐difference distribution is controlled by a spatial light modulator so that the interference intensity distribution can be modulated to user‐designed shapes. The congruence between the interference intensity distribution and the geometries on phase holograms enables the generation of phase holograms without complicated algorithms and time‐consuming calculations. This uniquely simple technique realizes flexible gray‐scale patterning on bulk material surfaces with a single femtosecond laser pulse. Thus, by using the on‐the‐fly technique, fabrication of large‐area surface structures is realized. Moreover, this technique is applied to fabricate complex structures through splicing. As an application example, three types of terahertz filters, including band‐stop and band‐pass filters, are fabricated successfully; their transmittance is in good agreement with the finite‐difference time‐domain simulation results.

Femtosecond Laser Direct Writing of Flexible Electronic Devices: A Mini Review

“…Femtosecond laser pulse interferometry has the advantages of high efficiency and a controllable period, which is an effective tool for constructing periodic functional micro-nanostructures [53,54]. For example, Li et al [55] proposed a novel patterning method for mask-free and flexible fabrication of surface structures through a time-saving spatiotemporal-interference-based femtosecond laser shaping technique, based on a Michelson interferometer. By using this technique, fabrication of large-area surface structures and three types of terahertz filters are fabricated successfully.…”

Femtosecond laser-induced periodic structures: mechanisms, techniques, and applications

“…Arbitrary spatial intensity distribution of femtosecond laser pulses can be modulated by loading a computergenerated hologram (CGH) on a SLM, and LIPSs can be processed in parallel with high efficiency 108 . For example, Hayasaki et al successfully realized the parallel processing of microstructures by loading a mixed-phase Fresnel lens on the SLM 109,110 .…”

Femtosecond Laser Precision Engineering: From Micron, Submicron, to Nanoscale

“…As a large area, mask-free, and noncontact nanofabrication method, LIL has been studied from 1967 to create numerous periodic structures on and inside targets employing a single step of laser irradiation [116], while the ultrafast laser irradiation is used for the interference manufacturing of metal substrate in 1996 exhibited better processing quality with respect to the nonultrafast laser processing experiments [117]. Since the rapid development of laser beam shaping technology, it is easy to flexibly modulate the optical distribution of femtosecond laser irradiation, which provides new possibilities in LIL processing [118]. The principle of LIL is dependent on the interference of two laser beams, which should be coherent for the formation of horizontal standing wave patterns.…”