Tunable nanowire nonlinear optical probe
One crucial challenge for subwavelength optics has been the development of a tunable source of coherent laser radiation for use in the physical, information and biological sciences that is stable at room temperature and physiological conditions. Current advanced near-field imaging techniques using fibre-optic scattering probes(1,2) have already achieved spatial resolution down to the 20-nm range. Recently reported far-field approaches for optical microscopy, including stimulated emission depletion(3), structured illumination(4), and photoactivated localization microscopy(5), have enabled impressive, theoretically unlimited spatial resolution of fluorescent bio-molecular complexes. Previous work with laser tweezers(6-8) has suggested that optical traps could be used to create novel spatial probes and sensors. Inorganic nanowires have diameters substantially below the wavelength of visible light and have electronic and optical properties(9,10) that make them ideal for subwavelength laser and imaging technology. Here we report the development of an electrode-free, continuously tunable coherent visible light source compatible with physiological environments, from individual potassium niobate (KNbO3) nanowires. These wires exhibit efficient second harmonic generation, and act as frequency converters, allowing the local synthesis of a wide range of colours via sum and difference frequency generation. We use this tunable nanometric light source to implement a novel form of subwavelength microscopy, in which an infrared laser is used to optically trap and scan a nanowire over a sample, suggesting a wide range of potential applications in physics, chemistry, materials science and biology.
Keywords: subwavelength photonics integration ; fluorescence microscopy ; semiconductor nanowires ; 2-photon excitation ; orthorhombic knbo3 ; refractive-indexes ; wave-guides ; resolution ; manipulation ; scale
Liphardt, J Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA Univ Calif Berkeley, Biophys Grad Grp, Berkeley, CA 94720 USA Univ Calif Berkeley, Lawrence Berkeley Lab, Phys Biosci Div, Berkeley, CA 94720 USA Univ Calif Berkeley, Lawrence Berkeley Lab, Div Mat Sci, Berkeley, CA 94720 USA Sony Corp, Mat Labs, Kanagawa 2430021, Japan, 183HT, Times Cited:21, Cited References Count:30
Record created on 2008-11-17, modified on 2016-08-08