Boosting second-harmonic generation in the LiNbO3 metasurface using high-guided resonances and bound states in the continuum

Zheng, Z ORCID: https://orcid.org/0000-0002-9676-2856, Xu, L ORCID: https://orcid.org/0000-0001-9071-4311, Huang, L, Smirnova, D, Hong, P, Ying, C ORCID: https://orcid.org/0000-0002-7279-1388 and Rahmani, M ORCID: https://orcid.org/0000-0001-9268-4793, 2022. Boosting second-harmonic generation in the LiNbO3 metasurface using high-guided resonances and bound states in the continuum. Physical Review B, 106 (12): 125411. ISSN 2469-9950

Preview

Text 1599593_Rahmani.pdf - Post-print Download (10MB) | Preview

Abstract

To date, second-harmonic generation (SHG) at nanoscale has concentrated on employing high-refractive-index nanostructures, owing to the strong field confinement at deep subwavelength scales based on optically resonant effects. However, nanostructures with lower index contrast between the structures and the surroundings generally exhibit weaker resonant effects and lower field confinement. To address this issue, by harnessing the large nonlinearity of LiNbO3, we propose an approach to employ guided resonances and bound states in the continuum (BICs) with a LiNbO3 metasurface consisting of a LiNbO3 disk array sitting on a LiNbO3 thin film. Such a system can transform the guided modes supported by a LiNbO3 thin film into high-quality guided resonances which can be excited directly under plane-wave illumination. Importantly, we further demonstrate strong field confinement inside a LiNbO3 thin film with a tailorable quality factor (Q factor) by realizing a Friedrich-Wintgen BIC. Such a unique mode engineering enables a record-high SHG efficiency of 5% under a pump intensity as low as 0.4 MW / cm2. Moreover, we reveal the influence of nonlinear resonances and cross coupling on the SHG by showing the anomalous SHG and efficiency tuning with the rotation of the crystal axis. Our work offers a route to construct enhanced SHG based on high- Q guided resonances and BICs, including low-index and high-index nonlinear materials.

Item Type:	Journal article
Publication Title:	Physical Review B
Creators:	Zheng, Z., Xu, L., Huang, L., Smirnova, D., Hong, P., Ying, C. and Rahmani, M.
Publisher:	American Physical Society (APS)
Date:	15 September 2022
Volume:	106
Number:	12
ISSN:	2469-9950
Identifiers:	Number Type 10.1103/physrevb.106.125411 DOI 1599593 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Laura Ward
Date Added:	16 Sep 2022 11:23
Last Modified:	16 Sep 2022 11:23
URI:	https://irep.ntu.ac.uk/id/eprint/47046

Actions (login required)

Edit View

Statistics

Views

Downloads