Monolithic lithium niobate photonic chip for efficient terahertz-optic modulation and terahertz generation
Yiwen Zhang, Jingwei Yang, Yuan-Song Zeng, Zhaoxi Chen, Hanke Feng, Sha Zhu, Kam Man Shum, Chi Hou Chan, Cheng Wang
Abstract
The terahertz (THz) range, bridging microwave and infrared frequencies, enables advanced imaging, sensing, communications, and spectroscopy. Analogous to microwave photonics, terahertz photonics offers a promising optical solution to critical THz challenges-THz-optical interfacing, including THz-optic modulation and optical generation of THz waves. We address these with a monolithic integrated photonic chip enabling efficient THz-optical bidirectional interaction. Leveraging strong second-order optical nonlinearity and optical/THz confinement in thin-film lithium niobate on quartz, the chip supports efficient THz-optic modulation and continuous THz generation up to 500 GHz. The measured continuous wave THz generation efficiency of 4.8 × 10−6/W at 500 GHz also marks a tenfold improvement over existing lithium niobate-based tunable THz generation devices. We further leverage the coherent nature of the optical THz generation process and on-chip modulators to realize 65 GHz high-speed electro-THz modulation. The chip-scale THz-photonic platform enables more compact, efficient, and cost-effective THz systems for communications, sensing, and spectroscopy. Here the authors showcase a monolithic photonic chip for efficient THz-optical interaction, using thin-film lithium niobate on quartz. It enables THz-optic modulation, 500 GHz continuous THz generation (10x more efficient than prior devices), and 65 GHz high-speed electro-THz modulation.