Thursday, April 11, 2013

Nanostructured Potential of Optical Trapping Using a Plasmonic Nanoblock Pair

Yoshito Tanaka , Shogo Kaneda , and Keiji Sasaki
We performed two-dimensional mapping of optical trapping potentials experienced by a 100 nm dielectric particle above a plasmon-resonant gold nanoblock pair with a gap of several nanometers. Our results demonstrate that the potentials have nanoscale spatial structures that reflect the near-field landscape of the nanoblock pair. When an incident polarization parallel to the pair axis is rotated by 90°, a single potential well turns into multiple potential wells separated by a distance smaller than the diffraction limit; this is associated with super-resolution optical trapping. In addition, we show that the trap stiffness can be enhanced by approximately 3 orders of magnitude compared to that with conventional far-field trapping.

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