Here we discuss recent results on the distance sensitivity of the near-field of subwavelength optical waveguides by measuring optical signals of fluorescent and plasmonic optical transmitters embedded in the evanescent field. By self-assembling thin polymeric coatings on nanoscale optical fibers (< 200 nm diameters), we were able to map out the optical field intensity around the fibers as a function of distance. Through experiments and simulations we demonstrate sub-nm sensitivity to objects moving in the evanescent field and discuss the dielectric-plasmonic effects that appear to enhance the distance sensitivity. In addition, we demonstrate real-time monitoring of single molecular displacements by linking molecules between the plasmonic nanoparticles and waveguide surface and applying forces. The simple design and ease of obtaining optical feedback on molecular movement makes this platform ideal for ultrasensitive force sensing devices and high-throughput molecular analysis.

Nanoparticle-enhanced detection of molecular displacements using the near-field of subwavelength optical waveguides

243rd National Meeting (2012)

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