title: Plasmon-Enhanced Second-Harmonic Generation Nanorulers with Ultrahigh Sensitivities.
abstract: Attainment of spatial resolutions far below diffraction limits by means of optical methods constitutes a challenging task. Here, we design nonlinear nanorulers that are capable of accomplishing approximately 1 nm resolutions by utilizing the mechanism of plasmon-enhanced second-harmonic generation (PESHG). Through introducing Au@SiO2 (core@shell) shell-isolated nanoparticles, we strive to maneuver electric-field-related gap modes such that a reliable relationship between PESHG responses and gap sizes, represented by "PESHG nanoruler equation", can be obtained. Additionally validated by both experiments and simulations, we have transferred "hot spots" to the film-nanoparticle-gap region, ensuring that retrieved PESHG emissions nearly exclusively originate from this region and are significantly amplified. The PESHG nanoruler can be potentially developed as an ultrasensitive optical method for measuring nanoscale distances with higher spectral accuracies and signal-to-noise ratios.
authors.affiliation: Department of Physics, Xiamen University , Xiamen 361005, China.
authors.forename: Shaoxin
authors.initials: S
authors.lastname: Shen
authors.affiliation: Department of Physics, Xiamen University , Xiamen 361005, China.
authors.forename: Lingyan
authors.initials: L
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Yuejiao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , Wuhan 430074, China.
authors.forename: Junbo
authors.initials: J
authors.lastname: Han
authors.affiliation: Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , Wuhan 430074, China.
authors.forename: Zongwei
authors.initials: Z
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Yuhan
authors.initials: Y
authors.lastname: He
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Ren
authors.affiliation: Department of Physics, Xiamen University , Xiamen 361005, China.|Institute for Complex Adaptive Matter, University of California , Davis, California 95616, United States.
authors.forename: Tien-Mo
authors.initials: TM
authors.lastname: Shih
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Physics, Xiamen University , Xiamen 361005, China.
authors.forename: Zhilin
authors.initials: Z
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.
authors.forename: Zhongqun
authors.initials: Z
authors.lastname: Tian
keywords: core−shell nanoparticles; finite-difference time-domain; plasmon nanoruler; second-harmonic generation; surface plasmon resonance