This paper demonstrates the detection of whispering–gallery mode (WGM) distribution in a fused silica micro disk resonator with a highly sensitive Nanonics Imaging cantilevered Pt/Au micro thermocouple probe and a Nanonics Imaging MultiView 4000 Scanning Probe Microscope.

Whispering gallery modes were excited by an evanescent tapered fiber with wavelengths in the 1550nm-1560nm range.  The thermocouple probe enabled detection of thermal distribution simultaneously with the topographic data.  As the tip penetrates the evanescence field, the light absorption leads to heating measured by the thermal tip, giving a thermal image of the light intensity distribution.  The thermal distribution was compared with NSOM results on the sample in transmission, reflection and collection modes.

Schematic of the experimental setup for thermal

mapping of  WGM in microdisk resonator



Thermal map of WGM in microdisk resonator


In Brief: This paper elegantly shows that the thermocouple probe has great potential for detection in the near field in visible and near-IR optical ranges and can be used as a tool to study different photonics devices.  

Published:  March 1, 2014/Vol.29, No.5/Optics Letters

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