Widely tuneable scattering-type scanning near-field optical microscopy using pulsed quantum cascade lasers

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

External organisations

  • Imperial College London

Abstract

We demonstrate the use of a pulsed quantum cascade laser, wavelength tuneable between 6 and 10 μm, with a scattering-type scanning near-field optical microscope (s-SNOM). A simple method for calculating the signal-to-noise ratio (SNR) of the s-SNOM measurement is presented. For pulsed lasers, the SNR is shown to be highly dependent on the degree of synchronization between the laser pulse and the sampling circuitry; in measurements on a gold sample, the SNR is 26 with good synchronization and less than 1 without. Simulations and experimental s-SNOM images, with a resolution of 100 nm, corresponding to λ/80, and an acquisition time of less than 90 s, are presented as proof of concept. They show the change in the field profile of plasmon-resonant broadband antennas when they are excited with wavelengths of 7.9 and 9.5 μm.

Details

Original languageEnglish
Article number213110
JournalApplied Physics Letters
Volume103
Issue number21
Publication statusPublished - 18 Nov 2013

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