Tuesday, December 1, 2015

Terahertz microscopy breakthrough revealed

Image: nanostructured optical materials boost photonic device efficiencies for THz microscopy
By: Rebecca Pool

Researchers from University College London, UK, and Sandia National Laboratories, US, have demonstrated optoelectronic probes for high spatial resolution terahertz microscopy.
Similar to infra-red waves and x-rays, terahertz waves allow observing objects and phenomena invisible to the human eye, but the clarity of THz images is limited by diffraction.
To advance resolution capabilities of near-field scanning probe microscopy with terahertz waves, Dr Mitrofanov and colleagues have developed a nanostructured terahertz detector and integrated it into the near-field microscopy probe.
The detector structure contains an array of optical nanoantennas and a distributed Bragg reflector.
When illuminated by a short optical pulse, this structure traps optical photons and activates a small terahertz detector, which allows sampling terahertz waves on the scale over 100 times smaller than the terahertz wavelength.
The researches anticipate that applications of these probes with terahertz time-domain spectroscopy will enable further scientific investigations of terahertz phenomena.
The technique of near-field scanning probe microscopy was pioneered using radio waves by Professor Sir Eric Ash in the Department of Electronic and Electrical Engineering at UCL, more than 40 years ago. This technique opened doors to investigations of sub-wavelength scale objects.
Research is published in ACS Photonics.

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