An apertureless near-field scanning optical microscope for imaging surface plasmons in the mid-wave infrared

摘要

An apertureless near-field scanning optical microscope (a-NSOM) setup is described. Special consideration is given to important system components. Surface plasmons are defined, as is their relationship to a-NSOM and their interaction with the scanning probe tip. We used this set-up to measure a metal-dielectric-metal (MDM) antenna integrated with a quantum cascade laser (QCL). The former is introduced and described. The role of the atomic force microscope (AFM) in the experiment is laid out and explained. Finally, the lock-in amplifier is explained. Next, the system setup is introduced and explained from the point of view of the light path taken by light generated in the laser. Finally, results are given for the MDM single nanorod antenna and the coupled MDM nanorod antenna. Simulation, topography, and NSOM images are shown. Lastly, several experimental issues are discussed as well as other types of NSOM.