The explosive growth of data traffic demands high-capacity and energy-efficient optical interconnects, motivating the development of integrated dense wavelength-division multiplexing (DWDM) devices with precise wavelength control and high-speed operation. In this work, we design and experimentally demonstrate a compact 8-channel DWDM multiplexer/demultiplexer based on x-cut thin-film lithium niobate. By employing cascaded asymmetric Mach–Zehnder interferometers (MZIs) with thermo-optic tuning, we achieve flexible spectral alignment, narrow channel spacing, and high temporal stability, resulting in a fabricated device with low insertion loss (<3 dB), interchannel crosstalk below −15 dB, and output power fluctuations within ±0.5 dB over 4000 s. Furthermore, we demonstrate coherent communication using the fabricated demultiplexer, achieving an aggregate data rate of 8 × 320 Gbps with 16-QAM at 80 Gbaud and bit error rates (BER) below the 7% hard-decision forward error correction (HD-FEC) threshold. These results demonstrate the feasibility of high-speed, integrated coherent DWDM transmission and highlight the potential of thermo-optically tuned TFLN-MZIs as a scalable and reconfigurable platform for next-generation optical networks and photonic systems.
Zhang et al. (Tue,) studied this question.