High‐Density and High‐Throughput Transceiver Module Based on the Lithium‐Niobate‐on‐Insulator Platform

ABSTRACT High‐density and high‐speed transceiver modules are essential for coping with the explosive growth of global data traffic. In this work, we demonstrate an ultra‐compact, high‐throughput transceiver module on the lithium‐niobate‐on‐insulator (LNOI) platform. On the transmitter side, the modulator has a footprint of only 100 µm while providing an electrical bandwidth exceeding 110 GHz, enabling 140‐Gbit/s On‐Off Keying (OOK) and 180‐Gbit/s 4‐level Pulse Amplitude (PAM4) operation per channel. Unlike micro‐ring modulators commonly implemented on LNOI, our device features a large 15‐nm free‐spectral range (FSR), theoretically supporting four channels with 3.2‐nm spacing or eight channels with 1.6‐nm spacing. The receiver side employs a multi‐channel flat‐top filter constructed from cascaded Bragg microcavities. The filter offers a 2‐nm 1‐dB bandwidth and insertion loss below 1 dB. Thanks to the tailored microcavity architecture, the total filter length is only about 250 µm. This significant footprint compression on both the transmitter and receiver sides enhances integration density and reduces overall chip area, providing a promising route toward high‐density, high‐speed transceiver modules on the LNOI platform.