One of the most powerful applications of multiprobe instrumentation for near field optical measurements is the novel capability for pump/probe experiments.  In NSOM pump/probe experiments, an optically active system is excited in the near-field (or pumped), and then mapped (or probed/detected) in the optical near fieldsimultaneously.  These optical pump-probe measurements enable the measurement of optical properties of nanostructures with the most accuracy and highest resolution.

However, now that there are two near field optical signals to measure, the complexity of interpreting these dual near-field type measurements is higher. Authors Angela Klein et al. of Institute of Applied Physics in Jena [Nano Letters, 2014]shed light specifically on exploring the polarization characteristics of the excited and detected light in dual-probe NSOM experiments using a Multiview 4000 system.  They find that the cantilever fiber probes, which are the conventional geometries of probes used in NSOM measurements, can both emit polarized light and function as polarization sensitive detectors.  Specifically, they make measurements on surface plasmon polaritons and find dipole-like SPP emission from the tips.

They conduct direct near field measurements  of dipole-like Surface Plasmon Polaritons (SPP) emission from a cantilevered aperture NSOM probe.  They study the polarization characteristics of Nanonics cantilevered single mode (SM) and multimode (MM) aperture NSOM probes in far-field and near-field.

A cantilevered SM NSOM probe with a high polarization factor was used for excitation while a MM cantilevered NSOM probe was used for collection. The experiment was done on a gold coated substrate.

This paper demonstrates that a cantilevered NSOM probe not only acts as SPP dipole, but can also be used as a polarization sensitive near–field detector.

In Brief: The MultiView 4000 Nanonics MultiProbe NSOM is the only tool that can allow for such kinds of experiments.  This microscope also assesses and confirms the polarization characteristics of cantilevered NSOM probes which leads to a better understanding of NSOM measurements.

PublishedNanoLetters, 2014

Click here for more information on the Nanonics MultiView 4000 system