Modal Phase-Matched Bound States in the Continuum for Enhancing Third Harmonic Generation of Deep Ultraviolet Emission

Modal Phase-Matched Bound States in the Continuum for Enhancing Third Harmonic Generation of Deep Ultraviolet Emission

ACS Nano

10.1021/acsnano.3c10471

http://dx.doi.org/10.1021/acsnano.3c10471

Omar A. M. Abdelraouf, Aravind P. Anthur, X. Renshaw Wang, Qi Jie Wang, Hong Liu

Electrical and Electronic Engineering, General Materials Science

23 January 2024

Omar A. M. Abdelraouf, Aravind P. Anthur, X. Renshaw Wang, Qi Jie Wang, and Hong Liu. (2024). Modal Phase-Matched Bound States in the Continuum for Enhancing Third Harmonic Generation of Deep Ultraviolet Emission. ACS Nano,18 (5), 4388-4397 DOI: 10.1021/acsnano.3c10471

Coherent deep ultra-violet (DUV) light sources are crucial for various applications such as nanolithography, biomedical imaging, and spectroscopy. DUV light sources can be generated using conventional nonlinear optical crystals (NLOs). However, NLOs are limited by their bulky size, inadequate transparency at the DUV regime, and stringent phase-matching requirements for harmonics generation. Recently, dielectric metasurfaces support high Q-factor resonances and offer a promising approach for efficient harmonic generation at short wavelengths. In this study, we demonstrated a crystalline silicon (c-Si) metasurface simultaneously exciting modal phase-matched bound states in the continuum (BICs) resonance at the fundamental wavelength of 840 nm with a higher degree of freedom for precise control of BICs resonance and a plasmonic resonance at the wavelength of 280 nm in the DUV to enhance third harmonic generation (THG). We experimentally achieved a Q-factor of ~180 owing to the relatively large refractive index of the c-Si and the geometric symmetry breaking of the structure. We realized THG at a wavelength of 280 nm with a power of 14.5 nW using a peak power density of 15 GW/cm2 excitation. The measured THG power is 14 times higher than the state-of-the-art THG dielectric metasurfaces using the same peak power density in the DUV regime, and the maximum obtained THG power enhancement factor is up to 48. This approach relies on the significant third-order nonlinear susceptibility of c-Si, the inter-band plasmonic nature of the c-Si in the DUV, and the strong field confinement of BICs resonance to boost overall nonlinear conversion efficiency to 5.2×10-6% in the DUV regime. Our work shows the potential of c-Si BICs metasurfaces for developing efficient and ultracompact DUV light sources using high-efficacy nonlinear optical devices.

Publisher Copyright

This research / project is supported by the A*STAR - AME programmatic grant
Grant Reference no. : A18A7b0058

This research / project is supported by the A*STAR - IRG
Grant Reference no. : A20E5c0094

This research / project is supported by the MOE - Academic Research Fund (AcRF) Tier 2
Grant Reference no. : MOE-T2EP50220-0005 and MOE-T2EP50120-0009

This research / project is supported by the MOE - Academic Research Fund (AcRF) Tier 3
Grant Reference no. : MOE2018-T3-1-002

This research / project is supported by the A*STAR - Strategic Programme Funds
Grant Reference no. : C210917001

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see 10.1021/acsnano.3c10471.

https://oar.a-star.edu.sg/communities-collections/articles/20557

1936-0851
1936-086X

Institute of Materials Research and Engineering