Lithium tantalate photonic integrated circuits for volume manufacturing

Chengli Wang; Zihan Li; Johann Riemensberger; Grigory Lihachev; Mikhail Churaev; Wil Kao; Xinru Ji; Junyin Zhang; Terence Blesin; Alisa Davydova; Yang Chen; Kai Huang; Xi Wang; Xin Ou; Tobias J Kippenberg

doi:10.1038/s41586-024-07369-1

Lithium tantalate photonic integrated circuits for volume manufacturing

Nature. 2024 May;629(8013):784-790. doi: 10.1038/s41586-024-07369-1. Epub 2024 May 8.

Authors

Chengli Wang^#^{1

2

3}, Zihan Li^#^{2

3}, Johann Riemensberger^{2

3}, Grigory Lihachev^{2

3}, Mikhail Churaev^{2

3}, Wil Kao^{2

3}, Xinru Ji^{2

3}, Junyin Zhang^{2

3}, Terence Blesin^{2

3}, Alisa Davydova^{2

3}, Yang Chen¹, Kai Huang¹, Xi Wang¹, Xin Ou⁴, Tobias J Kippenberg^{5

6}

Affiliations

¹ National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China.
² Institute of Physics, Swiss Federal Institute of Technology Lausanne, EPFL, Lausanne, Switzerland.
³ Center of Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
⁴ National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China. ouxin@mail.sim.ac.cn.
⁵ Institute of Physics, Swiss Federal Institute of Technology Lausanne, EPFL, Lausanne, Switzerland. tobias.kippenberg@epfl.ch.
⁶ Center of Quantum Science and Engineering, EPFL, Lausanne, Switzerland. tobias.kippenberg@epfl.ch.

^# Contributed equally.

Abstract

Electro-optical photonic integrated circuits (PICs) based on lithium niobate (LiNbO₃) 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 levels³ to be used in applications including data-centre communications⁴, high-performance computing and photonic accelerators for AI⁵. 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 (LiTaO₃), a material that has already been adopted commercially for 5G radiofrequency filters⁶ and therefore enables scalable manufacturing at low cost, and it has equal, and in some cases superior, properties to LiNbO₃. We show that LiTaO₃ can be etched to create low-loss (5.6 dB m^-1) PICs using a deep ultraviolet (DUV) stepper-based manufacturing process⁷. We demonstrate a LiTaO₃ 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 LiNbO₃, LiTaO₃ 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.