Integration of both active and passive photonic devices, such as waveguides, resonators, lasers, detectors, modulators, switches, isolators, transducers, and nonlinear converters, is the ultimate goal for a fully integrated photonic circuit critical for classical and quantum applications. Therefore, exploration of new photonic materials, which can serve as an efficient interface between electronic drive/control and photonic carrier, is critical.
Lithium niobate (LN) has been the “workhorse” of commercial optoelectronic system for decades, thanks to its excellent second-order nonlinearity (also a large electro-optic coefficient). We led several projects exploring both second- and third-order nonlinearities of integrated LN platform for nonlinear optical interactions, including ultrabroadband optical bandwidth spanning multiple octaves [1], Raman lasing [2], Kerr solitons [2], electro-optic combs [3], and second harmonic generation [1,4]. These work addresses the potential of the monolithic LN platform towards a fully integrated optical clock for microwave and optical wave synthesis, and towards programmable optoelectronic circuits with ultrafast feedback/control capabilities.
Some other achievements:
1) We harvested the frequency agility of such EO platform for a spectrally-tailored multiplexed spectrometer with high degree of phase stability [5];
2) We realized an on-chip frequency-domain shifter, which can shift light with near-unity shift efficiency and minimal insertion loss, compatible with microwave drives [6]. The device can be reconfigured as a beam splitter in the frequency domain via tailoring the “optical impedance”, an essential building block for future large-scale quantum information processor [6];
3) We explored an alternative solution of microwave to optical conversion assisted by acoustic phonons, via the large piezoelectric coefficient of LN. This device can play essential role in interfacing superconducting qubits with other quantum systems [7].
Related publication:
[1] M. Yu, et al., “Coherent two-octave-spanning supercontinuum generation in lithium-niobate waveguides,” Opt. Lett. 44, 1222 (2019). – Spotlight in Optics, Top Download in OL
[2] M. Yu, et al., “Raman lasing and soliton mode-locking in a lithium-niobate microresonator,” Light Sci. Appl. 9, 9 (2020).
[3] M. Yu, et al., “Chip-based lithium niobate frequency combs,” invited review, IEEE Photonics Technology Letters 31, 23 (2019).
[4] Y. Okawachi, M. Yu, et al., “Chip-based self-referencing using integrated lithium niobate waveguides,” Optica 7, 702 (2020).
[5] A. Shams-Ansari*, M. Yu*, Z. Chen*, et al., “An integrated lithium-niobate electro-optic platform for spectrally tailored dual-comb spectroscopy,” arXiv: 2003.04533 (2020).
[6] Y. Hu, M. Yu, et al., “Reconfigurable electro-optic frequency shifter,” Nature 599, 587–593 (2021)
[7] L. Shao, M. Yu, et al., “Microwave-to-optical conversion using lithium niobate thin-film acoustic resonators,” Optica 6, 12 (2019).