Simultaneous additive and subtractive three-dimensional nanofabrication using integrated two-photon polymerization and multiphoton ablation

Wei Xiong,Tommaso Baldacchini,Yang Gao,Masoud Mahjouri-Samani,Lan Jiang,Xiang Nan He,Yong Feng Lu,Yun Shen Zhou

doi:10.1038/lsa.2012.6

Abstract

An international team of researchers has combined two well-known fabrication techniques to produce intricate three-dimensional nanostructures. Yong Fen Lu and co-workers say that their novel approach could be used to make nanosized devices that are difficult to produce through either technique alone. Both techniques employ a femtosecond laser. The first — two-photon polymerization—is used to ‘draw’ 3D structures in a photocurable polymer. The second—femtosecond laser multiphoton ablation—is used to cut voids, such as channels, in the polymer. Combining these two techniques enables the efficient fabrication of complex three-dimensional nanostructures, such as integrated optical circuits and lab-on-a-chip devices.

Highlights

In recent years, three-dimensional (3D) micro-/nanofabrication techniques have attracted increasing attention, due to their promise in a wide range of applications including integrated optics,[1,2] plasmonics,[3,4] microbiology[5,6] and microelectromechanical systems.[7,8,9,10,11] Similar to 3D fabrication at macroscopic scales, 3D micro-/nanofabrication generally entails two fundamental approaches: additive and subtractive processes
The localized absorption of light allows for the confinement of either polymerization in the additive process or ablation in the subtractive process within submicrometer dimensions, beyond the optical diffraction limit of the near-infrared light
In twophoton polymerization (TPP), two near-infrared photons are required to initiate the additive polymerization,[12] which has a resolution of 100 nm in this study

Summary

INTRODUCTION

Three-dimensional (3D) micro-/nanofabrication techniques have attracted increasing attention, due to their promise in a wide range of applications including integrated optics,[1,2] plasmonics,[3,4] microbiology[5,6] and microelectromechanical systems.[7,8,9,10,11] Similar to 3D fabrication at macroscopic scales, 3D micro-/nanofabrication generally entails two fundamental approaches: additive and subtractive processes. Fs laser ablation (FLA) has been applied to a wide variety of materials.[14] When FLA is applied to transparent materials, structural or phase modification of the materials occurs, leaving behind permanent changes of refractive index or even voids.[14,15] FLA has found applications in a variety of fields such as optical data storage,[16] waveguide writing,[17] and nanosurgery.[18] Both additive and subtractive micro-/nanofabrication methods are established, they have been largely isolated and difficult to be integrated, due to either material incompatibilities or significant differences in laser processing parameters for TPP and FLA. The integrated fabrication method inherits the merits of both TPP and FLA, such as high resolution beyond the diffraction limit and features with sharp and clean edges, but it offers the possibility to produce novel device structures which are difficult to be fabricated by either TPP or FLA alone

Objective lens

RESULTS AND DISCUSSION

CONCLUSIONS