Front Cover: Microwave Characteristics and Bandwidth of BaTiO 3 Crystal Film Waveguide Electrooptic Modulator to Match the Light‐Wave Standard (Invited) (Phys. Status Solidi RRL 2/2026)

In the Research Article (DOI: 10.1002/pssr.202500340) by DeGui Sun and co-workers, a new model standard of the microwave bandwidth is derived for BaTiO3 crystal thin-film Mach–Zehnder Interferometer (MZI) type electrooptic (EO) intensity modulators. The theoretical models are exploited to investigate the microwave characteristics and to further comparatively optimize the microwave bandwidth. Mutual-validated results for the microwave modulation bandwidths are achieved between the simulations of the two theoretical models and further evidenced by the experimental measurements. Both the outcomes and conclusions obtained in theory and experiments show that the microwave characteristics and bandwidth are key limitations to the light-wave bandwidth performance.