低コストで高効率の新しいフォトニック集積回路(A new, low-cost, high-efficiency photonic integrated circuit)

2024-05-15 スイス連邦工科大学ローザンヌ校(EPFL)

＜関連情報＞

• https://actu.epfl.ch/news/a-new-low-cost-high-efficiency-photonic-integrated/
• https://www.nature.com/articles/s41586-024-07369-1

大量生産に適したタンタル酸リチウムフォトニック集積回路 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
Nature  Published:08 May 2024
DOI:https://doi.org/10.1038/s41586-024-07369-1

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.