Articles by Ryosuke Oketani in JoVE
Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle Hsuan Lee1, Kuan-Yu Li1, Yen-Ta Huang1, Po-Ting Shen1, Gitanjal Deka1, Ryosuke Oketani2, Yasuo Yonemaru2, Masahito Yamanaka2, Katsumasa Fujita2, Shi-Wei Chu1,3 1Department of Physics, National Taiwan University, 2Department of Applied Physics, Osaka University, 3Molecular Imaging Center, National Taiwan University Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.
Other articles by Ryosuke Oketani on PubMed
Measurement of a Saturated Emission of Optical Radiation from Gold Nanoparticles: Application to an Ultrahigh Resolution Microscope Physical Review Letters. Jan, 2014 | Pubmed ID: 24483931 We show that scattering from a single gold nanoparticle is saturable for the first time. Wavelength-dependent study reveals that the saturation behavior is governed by depletion of surface plasmon resonance, not the thermal effect. We observed interesting flattening of the point spread function of scattering from a single nanoparticle due to saturation. By extracting the saturated part of scattering via temporal modulation, we achieve λ/8 point spread function in far-field imaging with unambiguous separation of adjacent particles.
Point Spread Function Analysis with Saturable and Reverse Saturable Scattering Optics Express. Oct, 2014 | Pubmed ID: 25401635 Nonlinear plasmonics has attracted a lot of interests due to its wide applications. Recently, we demonstrated saturation and reverse saturation of scattering from a single plasmonic nanoparticle, which exhibits extremely narrow side lobes and central peaks in scattering images [ACS Photonics 1(1), 32 (2014)]. It is desirable to extract the reversed saturated part to further enhance optical resolution. However, such separation is not possible with conventional confocal microscope. Here we combine reverse saturable scattering and saturated excitation (SAX) microscopy. With quantitative analyses of amplitude and phase of SAX signals, unexpectedly high-order nonlinearities are revealed. Our result provides greatly reduced width in point spread function of scattering-based optical microscopy. It will find applications in not only nonlinear material analysis, but also high-resolution biomedical microscopy.