Integrated Brillouin photonics in thin-film lithium niobate
Kaixuan Ye, Hanke Feng, Randy te Morsche, Chuangchuang Wei, Yvan Klaver, Akhileshwar Mishra, Zheng Zheng, Akshay Keloth, Ahmet Tarık Işık, Zhaoxi Chen, Cheng Wang, David Marpaung
Abstract
Stimulated Brillouin scattering (SBS) is revolutionizing low-noise lasers and microwave photonics. However, a scalable and efficient integrated platform for Brillouin photonics has remained elusive. Here, we leverage the well-established thin-film lithium niobate (TFLN) platform to address these long-standing limitations. We report two distinct SBS processes on this platform, driven by surface acoustic wave (SAW) with 20-megahertz linewidth or bulk acoustic waves with a linewidth 200 times broader. Exploiting the strong SAW SBS gain, we demonstrate a narrowband internal net gain amplifier overcoming propagation losses. In addition, we achieve a stimulated Brillouin laser in TFLN, featuring a tuning range exceeding 20 nanometers and enabling high-purity radio frequency signal generation with an intrinsic linewidth of 9 hertz. Furthermore, we develop a programmable, multifunctional integrated Brillouin microwave photonic processor capable of notch filtering, bandpass filtering, or true time delay. This work bridges SBS with advanced TFLN technologies such as high-speed modulators and wideband optical frequency combs, unlocking new paradigms for integrated Brillouin photonics.