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Scientists develop room-temperature masers to transmit weak signals

Scientists develop room-temperature masers to transmit weak signals

Technology News |
By Christoph Hammerschmidt



The physics behind the maser technology are essentially similar to those of the laser, whose name stands for “light amplification by stimulated emission of radiation”. Both generate coherent electromagnetic radiation on a single frequency. “To date, lasers have been used primarily for communication in space, for example to maintain radio contact with the Voyager spacecraft, because masers can amplify very weak signals without amplifying the noise at the same time. This also makes them interesting for future communication technologies on earth,” says professor Christopher Kay from the Saarland University.

 

An important disadvantage of maser technology so far was that it required very low temperatures, which could only be achieved by the use of liquid helium. Together with research colleagues at the London Centre for Nanotechnology, Christopher Kay has now developed a maser that can be operated under normal room temperatures. The researchers use a sapphire resonator placed in a magnetic field to amplify the microwave radiation in a phase-stable manner. This radiation is generated by optically stimulating nitrogen voids in the diamond. In contrast to pure diamonds, which only contain carbon atoms and are therefore colourless, a small number of carbon atoms is replaced by a nitrogen atom in the diamond used here. The position next to the nitrogen atom, which normally contains a carbon atom, is empty.

This defect is called NV-Center (from Nitrogen Vacancy) and gives the diamond a purple color. It has a number of remarkable quantum properties and is therefore interesting for the development of new technologies as well, especially for nanoscale applications. For example, masers can be used for more precise measurements in investigations in space or in nanotechnology, which is summarized under the term nanometrology. “We also assume that wherever signals with low intensity are to be received over long distances and amplified without noise, maser opens up new possibilities,” says Kay.

It was already known in the scientific community that diamonds with NV centers can be used as the basis for a maser. The main focus of the research team’s work was to place a diamond in a sapphire resonator. An interesting aspect of this technology: The output frequency can be adjusted quite simply by changing the applied magnetic field. The current device operates at a frequency of 9 GHz. With commercially available magnet technologies, frequencies of up to 200 GHz could be achieved with the available room temperature maser.

The research was supported by the UK Engineering and Physical Sciences Research Council and the Henry Royce Institute. The development of the researchers from London and Saarbrücken was published in the renowned journal “Nature” (Continuous-wave room-temperature diamond maser: www.nature.com/articles/nature25970 )

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