Prof. Junqiu Liu
● The development and optimization of the "photonic Damascene process ", a novel but mature CMOS nanofabri-
cation technology for Si3N4 PIC which enables 90% fabrication yield and ultralow optical losses of only 0.5 dB/m
– currently the world lowest value found in any tight-optical-confinement PIC. [Nat. Commun. 12, 2236 (2021)].
● The first demonstration of coherent soliton microcombs of 10 and 20 GHz repetition rates in Si3N4, which could
have critical impact for high-spectral-efficiency coherent optical communications and low-noise microwave
synthesis. [Nat. Photon. 14, 486 (2020)].
● The first demonstration of hybrid integration of DFB laser chips with Si3N4 chips, which enables the so-far most-
compact and smallest microcomb modules operated at CMOS frequencies. [Nature 582, 365 (2020)].
● The first demonstration of wafer-scale heterogeneous integration of InP/silicon lasers on ultralow-loss Si3N4 PIC
–a decade-long standing goal pursued by the entire communities of integrated photonics and frequency combs.
[Science 373, 99 (2021)].
● The first demonstration of monolithically integrated acousto-optic modulators on Si3N4 using MEMS-based
piezoelectric aluminum nitride , for applications such as coherent LiDAR and magnetic-free on-chip optical
isolators. [Nature 583, 385 (2020)] & [Nat. Photon. 15, 828 (2021)].
● The first observation of backward stimulated Brillouin scattering (SBS) in Si3N4. [Phys. Rev. Lett. 124, 013902
(2020)].
● The ultralow-loss Si3N4 chips fabricated by him have been also used in several system-level applications such as
astronomical spectrometer calibration, massively parallel coherent LiDAR, mid-infrared dual-comb spectroscopy,
photonic neuromorphic computing,optical coherent tomography,photonic microwave filters, datacenter ultrafast
circuit switches, narrow-linewidth lasers, erbium-doped waveguide amplifiers, travelling-wave parametric amplif-
iers, and ultrafast electron transmission spectroscopy.
Prof. Junqiu Liu is currently a research fellow at International Quantum Academy / Hefei National Laboratory of Quantum Information Science, and a tenure-track assistant professor at the University of Science and Technology of China (USTC). He received Bachelor of Science from USTC in 2012. In 2016 he received Master of Science " mit Auszeichnung bestanden (with highest distinction) ” from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) in Germany. In 2020, he received Ph.D. from EPFL in Switzerland under the supervision of Prof. Tobias J. Kip-penberg. His doctoral thesis entitled "Silicon Nitride Integrated Nonlinear Photonics" won the 2021 EPFL Doctoral Prize , " for ground breaking experiments in the field of chip-scale frequency combs and the extraord-inary record of scientific accomplishments". After his postdoctoral research stay at EPFL till December 2021, he retur-ned to China and has established his independent research group since then.
His research has addressed multiple central topics in the development of chip-based microcombs and narrow-linewidth heterogeneous lasers using CMOS nanofabrication technology, and applied them for applications including inertial sensors , telecommunications, photonic computing , and laser spectroscopy. He has published more than 60 articles in peer-review journals, including 7 Nature,3 Science, 6 Nature Photonics/Physics, 15 Nature Communications, 3 Science Advances, 5 Optica, 2 PRL / PRX. Key achievements of him are following: