Customization and Information Encoding of Longitudinally Polarized Light Fields

The tightly focused structured light field displays a non-negligible component of the electric field in the direction of propagation, i.e., the longitudinal light field. The longitudinal light field results in various novel optical phenomena, such as transverse spin angular momentum and 3D topological light fields. However, it remains a challenge to generate customized longitudinal light fields. Here, based on inverse design theory, the longitudinal light field can be customized on demand under the tightly focusing condition, which allows to generate the longitudinal light field with controllable structured distribution for propagating waves or manipulate the complex structures for all the three components of the electric field. In experiment, an experimental system is built integrating the generation, customization, and detection of structured longitudinal light field, and the customization of the longitudinal light fields with various patterns is experimentally realized. The customized longitudinal light field structures may find applications such as information encoding, long-distance light manipulation, and novel light-matter interactions. As an example, information encoding is realized by the structured longitudinal light fields. The inverse design theory is introduced to customize the optical longitudinal field with arbitrary complex structures on demand. Based on the experimental system integrating the generation, manipulation, and detection of longitudinal field, different information can be encoded in the longitudinal field and be hidden in the transverse field, developing a new method of information encoding using the longitudinal field.image & COPY; 2023 WILEY-VCH GmbH