Calculated electric field intensity profiles at the glass interface focused by a high NA objective lens . The intensities of the transverse field in radial polarization and azimuthal polarization are magnified by 3 times and 1.5 times, respectively.
One-photon and two-photon excited fluorescence spectra of quantum dots. The cutoff at the shorter wavelength of the one-photon excited spectrum is due to the edge filter used in the experiment.
One-photon excited fluorescence images of QDs under (a) azimuthal and (b) radial polarizations. The incident laser wavelength and power are 532 nm and , respectively. Two-photon excited fluorescence images of QDs under (c) azimuthal and (d) radial polarizations. The incident laser wavelength and power are 800 nm and , respectively. All the images are consisting of 50 nm/pixel. Scale bar in the figure corresponds to .
(a) Model of FDTD calculation. The dielectric constants of silicon tip and glass substrate at 800 nm are set to and 2.110 23, respectively. The total calculated area is and the thickness of the glass layer is set to . An adaptive mesh with pixel sizes that varied from 2 to 56 nm is utilized for the calculation to reduce the computational time. The smallest pixels are at the tip apex. The gap between the tip and the substrate is 6 nm and modeled by 3 pixels. The tip diameter and the cone angle are 20 nm and 10°, respectively. The P-polarized incident angle is set to 80.7° and corresponds to a . The EF of the longitudinal electric field at the (b) X-Z plane at the tip axis and (c) X-Y plane at the gap. The EF is defined as the electric field with a tip divided by the field without a tip. (d) is the cross section profile of (c).
(a) System configuration of tip-enhanced two-photon excited fluorescence microscopy system. P: polarizer; NDF: neutral density filter; BE: beam expander; DM: dichroic mirror; EF: edge filter; SPF: short pass filter; APD: avalanche photo diode. (b) Profile of the reflected light intensity when the tip is scanned over the focused spot of a radially polarized beam. The scale bar in the figure corresponds to 200 nm.
(a) Tip-enhanced near-field and (b) far-field two-photon excited fluorescence spectra, in which the incident laser power was varied at 5, 10, 20, 30, 40, 50, and . The integrated spectral intensity of each spectrum as a function of the incident laser power is plotted in (c). The EF at each power is also indicated with a cross mark on the same figure.
(a) The Q curve of the silicon cantilever and (b) the force curve of the same cantilever used for the experiment in Fig. 8.
Magnified profiles of two-photon excited fluorescence images of (a) azimuthal and (b) radial polarizations. The scan step is 20 nm/pixel. (c) and (d) are the simultaneously obtained (c) topographic and (d) tip-enhanced two-photon excited fluorescence images, respectively. The scan step is 10 nm/pixel. All the images are of the same area. The incident laser power is . Both (e) and (f) are the cross-sectional profiles of images (c) and (d) as indicated by an arrow in each figure. Scale bar in the figure corresponds to 200 nm.
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