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Lighting the way to miniature devices

Date:
September 13, 2016
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
Electromagnetic waves created on a layer of organic molecules could provide the perfect on-chip light source for future quantum communication systems.
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Electromagnetic waves created on a layer of organic molecules could provide the perfect on-chip light source for future quantum communication systems.

A team of scientists including researchers at Agency for Science, Technology and Research (A*STAR), Singapore, has captured tiny flashes of light from an ultrathin layer of organic molecules sandwiched between two electrodes that could replace lasers and LEDs as signal sources for future miniature, ultrafast quantum computing and light-based communication systems.

To investigate electromagnetic waves called plasmons, which skim along the interface between two materials, Nikodem Tomczak from the A*STAR Institute of Materials Research and Engineering and colleagues collaborated with Christian A. Nijhuis from the National University of Singapore to construct a junction consisting of a layer of thiol molecules on a metal electrode and liquid gallium-indium alloy as a top electrode.

The team created plasmons by applying a voltage across the thiol layer. Although thiol is an insulator, the layer was thin enough for electrons to quantum tunnel between the electrodes, exciting plasmons on the thiol layer's surface in the process. The plasmons then decayed into photons, tiny pulses of light that Tomczak and his colleagues were able to detect.

"We were surprised that the light did not come from the whole junction, but instead just from very small spots that blink at different frequencies," said Tomczak.

The team found that the light generated by the plasmons was polarized, and that both the polarization and the wavelength of the light varied with the voltage applied across the junction and the molecules used to form the organic layer.

"The spots are diffraction-limited, polarized and their blinking follows power-law statistics," said Tomczak. "We need further experiments to confirm, but it is very similar to emission from other single photon sources, such as quantum dots or nanodiamonds."

Further evidence that the light is from plasmons decaying into a single photon came from Chu Hong Son and his team at the A*STAR Institute of High Performance Computing who modeled the spots as the product of the smallest possible source, a single dipole emitter, and achieved results consistent with the experimental observations.


Story Source:

Materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Content may be edited for style and length.


Journal Reference:

  1. Ji Fang Tao, Hong Cai, Yuan Dong Gu, Jian Wu, Ai Qun Liu. Demonstration of a Photonic-Based Linear Temperature Sensor. IEEE Photonics Technology Letters, 2015; 27 (7): 767 DOI: 10.1109/LPT.2015.2392107

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The Agency for Science, Technology and Research (A*STAR). "Lighting the way to miniature devices." ScienceDaily. ScienceDaily, 13 September 2016. <www.sciencedaily.com/releases/2016/09/160913120920.htm>.
The Agency for Science, Technology and Research (A*STAR). (2016, September 13). Lighting the way to miniature devices. ScienceDaily. Retrieved May 24, 2017 from www.sciencedaily.com/releases/2016/09/160913120920.htm
The Agency for Science, Technology and Research (A*STAR). "Lighting the way to miniature devices." ScienceDaily. www.sciencedaily.com/releases/2016/09/160913120920.htm (accessed May 24, 2017).

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