Fig. 5: Ferroelectric nematic liquid crystals (FN-LC)-enabled silicon photonic chip.
a A close-up picture of the chiplet incorporating 108 FN-LC Mach-Zehnder Modulators (MZM), the majority of which occupy a footprint of 0.4 mm2. Electrical wire bonds (EWB) are used to carry RF signals at the chip level. FN-LC has been selectively applied to a cluster of MZMs on the left for demonstration purposes. Top-down grating couplers and the photonic wire bonds (PWB) handle optical I/O for device and chip-level tests, respectively. b A scanning electron microscope (SEM) picture shows PWBs as extra optical I/O paths and their adiabatic surface tapers for low-loss power coupling. A 3D laser printer tool (Vanguard Automation–Sonata 1000) uses the two-photon polymerization effect to create free-form optical waveguides. The FN-LC needs to cover the electro-optic phase shifter (EOPS) sections on the silicon photonic (SiP) chip, leaving adequate space for the polymer required for PWB construction. c A microscopic zoomed-in view of the FN-LC-enabled modulators of various EOPS lengths. d A false-colored SEM image of the light-matter interaction-engineered finger-loaded strip waveguide with a zoomed-in view of its mode converter. e A magnified, false-colored SEM view of the PWB waveguide created between fibers and the on-chip surface taper.
