Rapid Two‐Photon Polymerization of an Arbitrary 3D Microstructure with 3D Focal Field Engineering

Abstract

Two‐photon polymerization is a powerful method for three‐dimensional (3D) precision nanofabrication. To facilitate the fabrication speed, for the first time, single‐exposure or single‐scan two‐photon polymerization of an arbitrary 3D microstructure with smaller or larger volume is demonstrated through focal field engineering. The constraints and the initial conditions of the Gerchberg–Saxton algorithm for the retrieval of the incident wavefront are adapted for the shape fidelity and the smoothness of the 3D focal field intensity distribution. As a result, a small 3D microstructure can be polymerized by a single exposure within 0.1 s, while a larger one can be formed by continuous polymerization of slices of the structure with one‐dimensional single scan with a speed of 6 µm s−1. The microlenses that generate vortex beams with different orbital angular momentums are polymerized to demonstrate the high fabrication precision. These pave the way for the rapid two‐photon polymerization of arbitrary 3D structures.

Rapid Fabrication of Continuous Surface Fresnel Microlens Array by Femtosecond Laser Focal Field Engineering

“…The surface of the lens is relatively smooth, showing the feasibility of this rapid fabrication technique. conditions of the Gerchberg-Saxton algorithm for the 3D focal field engineering (FFE) [22]. In addition, we choose the quadratic initial phase as an initial condition to reduce speckle caused by optical vortices.…”

“…Then, the corresponding holograms are calculated via the Gerchberg-Saxton algorithm, similar to the procedure described in Supporting Information in Ref. [22]. We adapt the constraints and the initial conditions of the Gerchberg-Saxton algorithm for the 3D focal field engineering (FFE) [22].…”

“…However, the traditional point-by-point scanning usually takes a long time, thus it is difficult to fabricate large-sized structures or arrays. Therefore, various solutions have been proposed to speed up the process, for example, the focal field engineering [18][19][20][21][22], the multi-focus generation for parallel processing [23][24][25], and the multi-beam interference [26,27] for specific periodic structures.…”

“…Previous researches have shown that the focal field engineering has great potential in fabricating 3D structures [22].…”

Etching-assisted femtosecond laser modification of hard materials

“…It is necessary to explore new strategies to improve the fabrication efficiency of femtosecond laser modification. For example, parallel processing technology, such as laser interference and spatial light modulator is being developed for multi-beam processing and for 3D focal field scanning [108][109][110][111] . Second, due to the strong nonlinear laser-matter interaction, the surface roughness of the fabricated structures is difficult to satisfy the requirements of optical devices.…”