[Optics Seminars OIST] by Dr Wenger

Title: Temperature in plasmonic nano-optical trapping

Speaker: Dr Jérome Wenger
CNRS research director, Institut Fresnel, France

Abstract:
Plasmonic nanostructures generate strong field gradients enabling efficient optical trapping of nano-objects. However, the infrared laser used for trapping is also partly absorbed into the metal. This leads to Joule heating and the generation of a local temperature gradient. Several questions then come out: how large is the temperature increase inside the plasmonic nanodevice? How to control it without changing the infrared laser power? And most importantly, what is its influence on the trap potential? In this seminar, I will present some of our current answers to these questions. Different fluorescence-based techniques will be presented to measure locally the temperature. This will lead to a discussion on the influence of the plasmonic design on the local temperature. We have also derived a different approach to experimentally measure the trap stiffness in plasmonic nanotweezers. Using this methodology, we discuss the optimization of the trap performance based on the plasmonic design. We also reveal the major role played by the surfactant added to the solution and relate this effect to the thermophoretic force.

Meeting URL:     https://oist.zoom.us/j/96709312884?pwd=QzQzamEvdk9jN1FFUXJTa2N2cXhnQT09&from=addon
Meeting ID:     967 0931 2884
Passcode:    203099