Researchers have successfully developed an economical and user-friendly 3D nanoprinting system capable of crafting intricate 3D structures with incredibly fine details. This cutting-edge technique proves precise enough to manufacture metamaterials and a diverse range of optical devices, including microlenses, micro-optical components, and metamaterials.
According to Cuifang Kuang, the lead of the research team from China’s Zhejiang Lab and Zhejiang University, “Our system employs a two-step absorption process to achieve nanometer-level accuracy in 3D printing, making it suitable for commercial production. It has versatile applications such as generating micro or nanostructures for studying biological cells or producing specialized optical waveguides for virtual and augmented reality gadgets.”
Unlike conventional 3D nanoprinting methods using expensive pulsed femtosecond lasers, the team’s innovation utilizes an integrated fiber-coupled continuous-wave laser diode that is not only cost-effective but also simple to operate.
Kuang emphasizes, “This novel approach democratizes 3D nanoprinting, making it accessible even to researchers unfamiliar with the typical optical systems required for such fabrication. In the future, this could lead to budget-friendly desktop 3D nanoprinters capable of providing precise nanoprinting to a wider audience.”
Creating a simple setup
When aiming to 3D print objects with a feature size around 100 nanometers, a method called two-photon absorption is typically employed. This technique utilizes costly femtosecond lasers to achieve precise absorption of photons in 3D, causing a liquid resin sensitive to light to solidify or polymerize.
Recently, an innovative approach called two-step absorption has emerged as an alternative to the traditional two-photon absorption. Developed by Vincent Hahn’s team at the Karlsruhe Institute of Technology, this method involves using a unique photoinitiator named benzil in conjunction with a single light source for polymerization. The researchers have further enhanced this process, devising a more streamlined and quicker 3D nanoprinting system based on two-step absorption. This system utilizes a 405-nanometer-wavelength integrated fiber-coupled laser.
In this new setup, for either 2D or 3D printing, the laser beam from a single-mode polarization-maintaining fiber is first collimated and directed towards galvanometric mirrors. Subsequently, it is focused onto the photosensitive material by a high-numerical aperture microscope objective.
Printing tiny objects
“The beauty of our straightforward system lies in its minimal need for numerous optical components to modulate the laser beam. This not only conserves costs but also reduces the occurrence of optical errors,” remarked Kuang. “Moreover, its exceptional stability and compatibility with most commercial microscopes are remarkable advantages.”
In their experimentation, the researchers effectively showcased their 3D nanoprinting setup by employing it at lower speeds to craft 2D line gratings and intricate 3D woodpile nanostructures with a lateral period measuring 350 nanometers. Impressively, when utilizing a swifter scan speed of 1000 microns per second, they were still able to produce 2D gratings boasting sub-200-nanometer resolution and sub-50-nanometer linewidth, all while operating at a laser power of less than 1 milliwatt.
Presently, the research team is devoted to enhancing both the writing speed and overall quality of their technique, all the while upholding the remarkable level of resolution achieved. This progression holds the promise of rendering the system even more feasible for an expanded array of applications.