Read on Demand Images in Laser‐Written Polymerizable Liquid Crystal Devices

Two‐photon laser writing is a powerful technique for creating intricate, high resolution features in polymerizable materials. Here, using a single‐step process to microfabricate polymer inclusions, the ability to generate read‐on‐demand images and identification codes in a liquid crystal (LC) device is demonstrated. These micrometer‐sized polymer features are encoded directly into LC devices using direct laser writing, which locks‐in the local molecular orientation at the moment of fabrication. By reading the devices with the same voltage amplitude that is used to write the polymer structures, features can be made to disappear as the director profile becomes homogeneous with the surrounding regions, effectively cloaking the structure for both polarized and unpolarized light. It is shown how this process can be used to create micrometer‐scale reconfigurable emoticons and quick‐response codes within a fully assembled LC device, with potential use in authenticity and identification applications. A novel method of refractive index matching within polymerizable liquid crystal devices is demonstrated using optical microfabrication with a femtosecond laser. Micrometer‐sized polymer features are shown to have a voltage‐dependent visibility when examined with polarized and unpolarized light. The concept is used to demonstrate read‐on‐demand images such as “microbicycle” stop‐frame animation and a reconfigurable quick‐response code.