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Photonic nano-structures enhance sensitivity and spatial resolution of terahertz microscopy

Research published in the ACS Photonics journal

A team lead by Dr Mitrofanov demonstrated optoelectronic probes for high spatial resolution terahertz microscopy. The research, published in the journal ACS Photonics this week, will aid in development of future terahertz technologies.

Similar to infra-red waves and x-rays, terahertz waves allow observing objects and phenomena invisible to the human eye. However clarity of THz images is limited by diffraction, the property of light to pass around objects smaller than the light’s wavelength. To advance resolution capabilities of near-field scanning probe microscopy with terahertz waves, the research team developed a nano-structured terahertz detector and integrated it into the near-field microscopy probe.

The detector structure contains an array of optical nano-antennas 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 a powerful analytical technique, called terahertz time-domain spectroscopy (THz-TDS), will enable further scientific investigations of terahertz phenomena.

The technique of near-field scanning probe microscopy was pioneered using radio waves by Prof. Sir Eric Ash in the Department of Electronic and Electrical Engineering over 40 years ago. This technique opened doors to investigations of sub-wavelength scale objects.

This research was supported by the Royal Society [Grant No. UF 130493] and it was carried out in collaboration with scientists at the Center for Integrated Nanotechnologies, Sandia National Laboratory.

Original article:

O. Mitrofanov et al., "Photoconductive terahertz near-field detector with a hybrid nanoantenna array cavity," ACS Photonics