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Direct Laser Writing in Liquid Crystals & Polymers

Aberration-corrected Direct Laser Writing in Liquid Crystals & Polymers

Two-photon polymerization direct laser writing (TPP-DLW) is a technique for creating micro- and nanoscale polymer objects in polymerisable resins and is a powerful additive manufacturing/3D printing technique. The capabilities of TPP-DLW go well beyond that offered by traditional lithographic processes, as it provides true 3D structuring rather than 2D layer-by-layer fabrication. It also enables rapid prototyping and flexible, direct conversion from 3D design to 3D microstructure as well as the remarkable ability to create sub-diffraction limited polymer features. By translating a photopolymerizable liquid crystal in a controlled manner relative to the laser focus, 3D structures can be built-up from polymerized voxels (the 3D analogy of pixels) formed via free-radical polymerization. We are working closely with the Dynamic Optics and Photonics group of Professor Martin Booth and Dr Patrick Salter to develop new electro-optic effects and photonics technologies by writing micron-sized polymer features into polymerizable liquid crystal materials and devices. 

Figure 1. Read-on-Demand Microimages in Liquid Crystal Devices.

Figure 2. Laser-written polymer bicycle in a liquid crystal device.

Figure 3. Laser written QR code.

A key challenge for emerging nanoprinting techniques is to increase the functionality and capabilities of the resin materials. We are directly addressing this by developing tunable resins using stimuli-responsive liquid crystal materials that change their optical and physical properties in response to external fields. Developing such bespoke resins that incorporate polymerizable liquid crystal molecules has allowed us to lock-in different alignments of the liquid crystal director (the average pointing direction of the molecules). Thus from a single resin, we are able to engineer polymer structures with different material properties in a single-step fabrication process, leading to new electro-optic capabilities and practical applications.