To address this, a group of researchers from East China Normal University, Nanjing University, China Jiliang University, Shanxi University and the Chinese Academy of Sciences in China have integrated metasurfaces with an electrically controlled lithium niobate on insulator (LNOI) photonic integrated circuit (PIC) chip and demonstrated the dynamic control of free-space wavefront shaping and switching at gigahertz rates (H. Zhong et al. Adv. Photonics 6, 016005 (2024); https://doi.org/10.1117/1.AP.6.1.016005).

The device in question is designed and fabricated on an X-cut LNOI platform to provide the best electro-optical performance. An arbitrary polarized light could be generated by combing a waveguide with two orthogonally propagated modes and nano-scatterers at specific positions. By introducing a Mach–Zehnder interferometer (MZI) and a phase shifter along with two pairs of electrodes, both the amplitude and the phase of the two orthogonal modes can be controlled. This enables the generation of light with arbitrary polarizations covering the entire surface of the Poincaré sphere at high speed. A specially designed silicon metasurface is then strategically positioned on the slab waveguide to achieve the desired functionalities and to facilitate high-speed modulation or switching, simply by adjusting the voltages applied to the electrodes of the MZI and the phase shifter.