Evidence of High-Order Nonlinearities in Supercontinuum White-Light Generation from a Gold Nanofilm

TY - JOUR

T1 - Evidence of High-Order Nonlinearities in Supercontinuum White-Light Generation from a Gold Nanofilm

AU - Chen, Junsheng

AU - Krasavin, Alexey

AU - Ginzburg, Pavel

AU - Zayats, Anatoly V.

AU - Pullerits, Tõnu

AU - Karki, Khadga Jung

N1 - Publisher Copyright: © 2018 American Chemical Society.

PY - 2018/5/16

Y1 - 2018/5/16

N2 - White-light supercontinuum generation can be readily observed when gold nanostructures are irradiated with short pulses of light. It is believed that the nanostructures enhance the optical fields, which facilitates the supercontinuum white-light generation from the surrounding environment or the substrate. Here, we investigate the different nonlinear processes that contribute to the generation of the supercontinuum from plasmonic nanostructures themselves using a technique that isolates the different nonlinear contributions. By exciting a gold nanofilm with a pair of frequency shifted optical frequency combs, we demonstrate multiple modulation frequencies in the supercontinuum. Their dependence on the excitation intensity reveals that the supercontinuum originates from different orders of nonlinear light-matter interactions. This contrasts with the supercontinuum generation by a cascaded third-order optical nonlinear response in traditional dielectric-based white-light sources. The while-light emission from the gold nanofilm is efficient even under relatively weak excitation indicating that nonlocal effects in nanostructures may facilitate the supercontinuum generation by adding new pathways in the nonlinear interactions. The results provide experimental basis for the understanding of the collective nonlinear response of free-electrons in the metallic nanostructures and associated nonlinear processes, which are crucial in development of nonlinear metasurfaces and nanophotonic devices.

AB - White-light supercontinuum generation can be readily observed when gold nanostructures are irradiated with short pulses of light. It is believed that the nanostructures enhance the optical fields, which facilitates the supercontinuum white-light generation from the surrounding environment or the substrate. Here, we investigate the different nonlinear processes that contribute to the generation of the supercontinuum from plasmonic nanostructures themselves using a technique that isolates the different nonlinear contributions. By exciting a gold nanofilm with a pair of frequency shifted optical frequency combs, we demonstrate multiple modulation frequencies in the supercontinuum. Their dependence on the excitation intensity reveals that the supercontinuum originates from different orders of nonlinear light-matter interactions. This contrasts with the supercontinuum generation by a cascaded third-order optical nonlinear response in traditional dielectric-based white-light sources. The while-light emission from the gold nanofilm is efficient even under relatively weak excitation indicating that nonlocal effects in nanostructures may facilitate the supercontinuum generation by adding new pathways in the nonlinear interactions. The results provide experimental basis for the understanding of the collective nonlinear response of free-electrons in the metallic nanostructures and associated nonlinear processes, which are crucial in development of nonlinear metasurfaces and nanophotonic devices.

KW - nonlinear interactions

KW - nonlocal response

KW - rough metal films

KW - white-light generation

UR - http://www.scopus.com/inward/record.url?scp=85047226176&partnerID=8YFLogxK

U2 - 10.1021/acsphotonics.7b01125

DO - 10.1021/acsphotonics.7b01125

M3 - 文章

AN - SCOPUS:85047226176

SN - 2330-4022

VL - 5

SP - 1927

EP - 1932

JO - ACS Photonics

JF - ACS Photonics

IS - 5

ER -