An 8×240 Gbps dense wavelength division multiplexing transmitter with lithium tantalate

Dense wavelength division multiplexing (DWDM) is regarded as a revolutionary solution that significantly enhances transmission capacity. However, DWDM in electro-optic (EO) material platforms faces bottlenecks including limited channel numbers, large insertion losses (ILs), and limited spectral efficiency. Here, an 8×240 Gbps DWDM transmitter at O band is demonstrated on a lithium-tantalate-on-insulator platform through proposing a robust flat-top optical filter based on a novel coupled Fabry-Perot (FP) cavity. The flat-top optical filter shows overall high performance of a low IL of ~0.1–0.4 dB, a large free spectral range of 12 nm, a high extinction ratio (ER) of ~26 dB, and a large fabrication tolerance. The 8-channel DWDM transmitter is further realized with uniform channel spacings of 200 GHz and a total data capacity of 8×240 Gbps. Therefore, it offers a critical strategy for enhancing the capacity of optical links, holding significant promise for widespread application in fields like data centers and artificial intelligence. Researchers demonstrate an 8×240 Gbps DWDM transmitter on a thin-film lithium tantalate platform for the O-band, using a novel flat-top optical filter based on coupled Fabry–Perot cavities. It achieves low insertion loss (0.1–0.4 dB), a high extinction ratio (~26 dB), and a 12 nm free spectral range, showing promise for high-capacity optical links in AI and data centers.