Ultrafast dynamics of near-field enhancements at an off-resonance nano-dimer via femtosecond laser excitations
State Key Laboratory for Manufacturing Systems Engineering & Key Laboratory of Photonics Technology for Information, School of Electronics & Information Engineering, Xi'an Jiaotong University - Xi'an 710049, China
Received: 3 February 2015
Accepted: 10 April 2015
Giant electric-field enhancements localized on nano-antennas are important for the optical near-field applications in fields such as super-resolution imaging, near-field optical tweezers, and photothermal therapy. Physically, the field enhancement requires plasmon resonance with respect to structure matching. We report a tunable near-field effect, including localized electric-field enhancement and resistive heating at an off-resonance Au nano-sphere dimer via femtosecond laser irradiation. The near field was strongly modified (up to 81 times) with respect to time evolution at a laser fluence of . The results are explained as thermal dynamics manipulation of the Au nano-sphere dimer plasmon resonances. This study provides a new alternative route to tailoring the near-field enhancement for wide applications in nano-antennas.
PACS: 79.20.Ds – Laser-beam impact phenomena / 79.20.Eb – Laser ablation / 78.20.nb – Photothermal effects
© EPLA, 2015