Lithium tantalate photonic integrated circuits for volume manufacturing

Abstract Electro-optical photonic integrated circuits (PICs) based on lithium niobate (LiNbO 3 ) have demonstrated the vast capabilities of materials with a high Pockels coefficient 1,2 . They enable linear and high-speed modulators operating at complementary metal–oxide–semiconductor voltage levels 3 to be used in applications including data-centre communications 4 , high-performance computing and photonic accelerators for AI 5 . However, industrial use of this technology is hindered by the high cost per wafer and the limited wafer size. The high cost results from the lack of existing high-volume applications in other domains of the sort that accelerated the adoption of silicon-on-insulator (SOI) photonics, which was driven by vast investment in microelectronics. Here we report low-loss PICs made of lithium tantalate (LiTaO 3 ), a material that has already been adopted commercially for 5G radiofrequency filters 6 and therefore enables scalable manufacturing at low cost, and it has equal, and in some cases superior, properties to LiNbO 3 . We show that LiTaO 3 can be etched to create low-loss (5.6 dB m −1 ) PICs using a deep ultraviolet (DUV) stepper-based manufacturing process 7 . We demonstrate a LiTaO 3 Mach–Zehnder modulator (MZM) with a half-wave voltage–length product of 1.9 V cm and an electro-optic bandwidth of up to 40 GHz. In comparison with LiNbO 3 , LiTaO 3 exhibits a much lower birefringence, enabling high-density circuits and broadband operation over all telecommunication bands. Moreover, the platform supports the generation of soliton microcombs. Our work paves the way for the scalable manufacture of low-cost and large-volume next-generation electro-optical PICs.