We report a large group velocity dispersion of hybrid modes in LiNbO3-on-insulator multimode rib waveguide. A peak dispersion of $\pm$ 49000 ps/(nm.km) is obtained in the mode hybridization region between TE00 and TM10 modes with a full width at half maximum (FWHM) of 10 nm. Dispersion for hybrid modes is tunable around $\pm$ 15000 ps/(nm.km), $\pm$ 22000 ps/(nm.km) and $\pm$ 49000 ps/(nm.km) occurring at wavelengths of 1272 nm, 1372 nm, and 1496 nm respectively in the telecommunication band. In the wavelength range from 1530 to 1600 nm, proposed rib waveguide is free of hybrid modes. In this region the waveguide exhibits a flat dispersion profile for all eight guided modes with a maximum < 1000 ps/(nm.km).

Antimicrobial coatings are essential for controlling the pathogen spreading and their interface with the hosts. These may be applied to masks as additional security to the wearer over the pore filtration or applied to surfaces that are often hand-touched as the nanocoating can deactivate the virus irreversibly. We have synthesized an antimicrobial nanoformulation containing mixed metal oxides (MMO) of TiO₂, ZnO, SiO₂, CuO with silver nanoparticles (MMO-Ag) capped with a cationic surfactant by the hydrothermal route and is amenable for scale-up. The developed nanoformulation possesses a high specific surface area of 73.5 m²g^-1. The nanoformulation exhibits excellent antimicrobial properties against gram-negative (E. coli), gram-positive (S. aureus) bacteria, and bacteriophage virus, superior to that of the spherical morphology. The minimum inhibition concentration (MIC) of nanoformulation is 107 µg/mL against S. aureus bacteria. The enhanced antimicrobial properties of spiky nanoformulation are attributed to sharp nanometric tips that can physically puncture the cell membrane of the pathogen via a mechano-bactericidal effect. The net attraction between the spiky MMO particle and bacteria is 10² times when compared to smooth MMO particles as estimated by the modified DLVO theory. The developed nanoformulation coated fabric exhibits self-cleaning properties on exposure to UV light by facilitating complete degradation of the bacteria owing to the photocatalytic component present in the nanoformulation that gets enhanced due to electric field intensity near the tips, augmented by silver nanoparticles.

Electro-optic modulators (EOMs) are crucial devices for modern communication enabling high bandwidth optical communication links. Traveling wave electrodes are used to obtain high-speed modulation in these EOMs. We present the electrode design and analysis along with the study of effects of changing orientation on device performance for a thin-film lithium niobate tunable Mach–Zehnder interferometer (MZI) that offers sub-THz bandwidth operations. High velocity and impedance matching with low RF attenuation, high third-order SFDR (∼121 dB/Hz^2/3) and a low half-wave voltage length product (1.74 V.cm) have been achieved for a bandwidth of 136 GHz. High-speed digital modulation using multi-level signal formats (PAM-2, QAM-4 and QAM-16) with low BER for 400 Gbps data has been demonstrated to assess the digital performance of the device.