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

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.
Authors:
; ; ;  [1] ;  [2]
  1. The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)
  2. Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2BT (United Kingdom)
Publication Date:
OSTI Identifier:
22254003
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 103; Journal Issue: 21; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANTENNAS; GOLD; IMAGES; LASERS; OPTICAL MICROSCOPES; OPTICAL MICROSCOPY; PULSES; RESOLUTION; SAMPLING; SCATTERING; SIGNAL-TO-NOISE RATIO; SIMULATION; SYNCHRONIZATION; WAVELENGTHS