TE/TM-pass polarizers based on the lithium niobate–silicon nitride hybrid platform are numerically proposed for the first time, to the best of our knowledge. By utilizing the lateral leakage of a shallowly etched rib waveguide, 1-mm-long TE/TM-pass polarizers with high extinction ratios of 28.72/24.03 dB are obtained. Because of the anisotropy of the lithium niobate, the lateral leakage of TE/TM polarization modes can occur along crystallographic z / y directions, respectively. Such TE/TM-pass polarizers can be integrated in the same wafer.

A four-mode (de-)multiplexer with transverse electric field light ( T E 0 − T E 3 ) is experimentally demonstrated on a thin film lithium niobate–silicon rich nitride hybrid platform. Enabled by cascaded asymmetrical directional couplers, a (de-)multiplexer with low insertion loss (0.38 dB to 1.6 dB) and low cross talk ( − 18.46 d B to − 20.43 d B ) is obtained at 1550 nm. All channels have cross talk < − 16 d B from 1480 nm to 1580 nm. The transmission of 4 × 50 Gbps on–off keying signals is experimentally achieved on the proposed (de-)multiplexer. Experimental results show that the proposed (de-)multiplexer is a promising approach to enhance the transmission capacity in thin film lithium niobate based photonics integrated circuits.

A four-channel coarse wavelength division multiplexing (CWDM) (de)multiplexer on a thin film lithium niobate–silicon rich nitride hybrid platform has been designed, fabricated, and experimentally measured. Enabled by cascaded multimode waveguide Bragg gratings, the (de)multiplexer has a box-like spectral response, wide 1-dB bandwidth (10 nm), low excess loss ( < 1.08 d B ), and low channel cross talk ( < − 18 d B ). The central wavelengths of the (de-)multiplexer are 1531/1551/1571/1591 nm, which align to the wavelength grids stipulated by the standard ITU-T G.694.2.

We propose and demonstrate a Michelson interferometer modulator with integrated Bragg reflectors on a silicon-rich nitride–thin-film lithium niobate hybrid platform. High-reflectivity Bragg reflectors are placed at the ends of both arms, which double the electro-optic (E-O) interaction length and reduce the velocity mismatch between the microwave and optical wave. The presented Michelson interferometer modulator achieves a measured half-wave voltage length product as low as 1.06 V cm and high-speed modulation up to 70 Gbps. A 3-dB E-O bandwidth beyond 40 GHz is also achieved, which is, to the best of our knowledge, the highest modulation bandwidth of Michelson interferometer modulators.

In this letter, we experimentally demonstrate the first slow-light Mach-Zehnder modulator (MZM) on a hybrid ithin-film Lithium Niobate platform. The Bragg grating waveguides are served as phase shifters, which enhance the modulation efficiency with the slow-light effect. Compared with large-signal modulation efficiency (V _π · L = 0.67 V·cm) and an ultra-compact footprint (0.3 mm ×1.2 mm). Data transmission up to 60 Gbps and an on-chip insertion loss of 1.9 dB are also achieved. This modulator provides a potential solution for high-intensity integration, low-power transmission, and optical biosensing.

We propose a novel optical 1×2 power splitter based on an asymmetric ladder-shaped multimode interference (MMI) coupler in silicon-on-insulator (SOI) which has an ultra-compact size of 3.3 µm×2.4 µm. A trapezoid with a small region is removed from the bottom left corner of the MMI coupler to achieve variable splitting ratio. The comparison with the asymmetric rectangular 1×2 splitter is numerically analyzed. By carefully optimizing the width of input taper, the proposed splitter shows a low phase deviation for the two output ports while keeping both of a low-loss performance and feasible splitting ratio. The simulated results show that the splitter can operate with an insertion loss less than 0.67 dB, a large range of splitting ratio from 50:50 to 11:89 and an ultra-low phase deviation less than 2.8^° among the C band spectra.