Yaowen Hu

Optics and photonics, the field of the study of light, have reshaped human life with innovation and breakthroughs on numerous novel devices. Photonic coupled-resonators have been promising to change the “status quo” and offer many exciting advantages over single-resonator and waveguide-based systems.

To push the innovation of the next generation of photonic devices beyond single-resonator and waveguide-based systems, Yaowen Hu has devoted years of research efforts on developing the platform of photonic electro-optic coupled-resonators on thin-film lithium niobate (TFLN). With the efforts and breakthrough on both fabrication and theory, he built up the platform for photonic coupled resonators on TFLN, a platform that support photonic multi-level systems with electro-optic transition.

Using this platform, in 2021, Yaowen demonstrated electro-optic frequency shifters by combining the general critical coupling (GCC) with multiple optical energy levels coupled to continuum. He first demonstrated record-high performances of frequency shifting of 10-30 GHz with 99% shift efficiency and 0.45 dB on-chip insertion loss. Furthermore, he showed that such a platform can not only lead to record high performance, but also functionality that did not exist before.

In 2022, Yaowen showed that this platform can enable superior frequency combs. By applying coupled-resonators and the GCC to electro-optic combs, he demonstrated a 100-fold higher efficiency (30%) and 2.2-times wider span (132 nm) than previous state-of-the-art integrated electro-optic comb sources. Beyond these, he also applied this platform to explore the recent emerging photonic synthetic dimensions, demonstrating the first four-dimensional frequency crystals on TFLN and frequency-domain synthetic mirrors (with reflectivity > 0.9999)​.

The above results prove that the advantages of thin-film lithium niobate are exactly what is needed for photonic coupled resonators. Yaowen's related research has promoted the breakthrough of thin-film lithium niobate, an emerging photonic chip platform, and promoted the development of storage, transmission, computing and detection of next-generation information technology.