Controlling waves in space and time for imaging and focusing in complex media

In complex media such as white paint and biological tissue, light encounters nanoscale refractive-index inhomogeneities that cause multiple scattering. Such scattering is usually seen as an impediment to focusing and imaging. However, scientists have recently used strongly scattering materials to focus, shape and compress waves by controlling the many degrees of freedom in the incident waves. This was first demonstrated in the acoustic and microwave domains using time reversal, and is now being performed in the optical realm using spatial light modulators to address the many thousands of spatial degrees of freedom of light. This approach is being used to investigate phenomena such as optical super-resolution and the time reversal of light, thus opening many new avenues for imaging and focusing in turbid medi

Complementarity Of Intensity And Optical Force Measurements In Scanning Probe Microscopy

We demonstrate that intensity and optical force gradient maps provide complementary measures of the near-field light distribution in scanning probe microscopy (SPM). Sensitivity of metal coated SPM probes to magnetic fields is shown. © OSA 2013

Discrimination Of Field Components In Optical Probe Microscopy

We demonstrate that the conventional optical signal in near-field scanning optical microscopy and the optical force induced topography contain complementary information about the complex three-dimensional field distribution. Crucially, the additional information about the field distribution can be retrieved without increasing the measurement complexity. © 2012 Optical Society of America

Optical Multifrequency Scanning Probe Microscopy

We present the design and numerical optimization of an all-polymer fiber as a luminescent solar concentrator. Large-area, lightweight, and flexible fabrics constructed of such fibers are a low-cost solar-energy harvesting alternative useful for mobile applications. © 2012 OSA

Post-fabrication Voltage Controlled Resonance Tuning of Nanoscale Plasmonic Antennas

Voltage controlled wavelength tuning of the localized surface plasmon resonance of gold nanoparticles on an aluminum film is demonstrated in single particle microscopy and spectroscopy measurements. Anodization of the Al film after nanoparticle deposition forms an aluminum oxide spacer layer between the gold particles and the Al film, modifying the particle-substrate interaction. Darkfield microscopy reveals ring-shaped scattering images from individual Au nanoparticles, indicative of plasmon resonances with a dipole moment normal to the substrate. Single particle scattering spectra show narrow plasmon resonances that can be tuned from ∼580 to ∼550 nm as the anodization voltage increases to 12 V. All observed experimental trends could be reproduced in numerical simulations. The presented approach could be used as a general postfabrication resonance optimization step of plasmonic nanoantennas and devices. © 2012 American Chemical Society