6G terahertz waveform synthesis in a photonic chip
Researchers at EPFL and ETH Zurich in Switzerland have developed a thin-film photonic chip that can generate finely tailored terahertz frequency waves for next generation 6G applications.
Researchers led by Cristina Benea-Chelmus in the Laboratory of Hybrid Photonics (HYLAB) in EPFL’s School of Engineering worked producing waveforms in the ‘terahertz gap’ between 300GHz and 30THz. These frequencies are too fast for today’s electronics and telecommunications devices, but too slow for optics and imaging applications.
The photonic integrated circuit (PIC) uses a thin film of etched lithium niobate on a silicon substrate to tailor the frequency, wavelength, amplitude, and phase. This uses channels as waveguides, from which microscopic antennas broadcast terahertz waves generated by light from optical fibres.
Such precise control over terahertz radiation means that it can now potentially be used for next-generation applications in both the electronic and optical realms. The results have recently been published in Nature Communications.
“Seeing the devices emit radiation with properties that we predefined was a confirmation that our model was correct,“ says co-first author Alexa Herter, currently a PhD student at ETH Zurich.
“This was made possible due to the unique features of lithium niobate integrated photonics,” adds co-first author Amirhassan Shams-Ansari, a postdoctoral fellow at Harvard University who also worked on the project.
“Generating waves at very high frequencies is extremely challenging, and there are very few techniques that can generate them with unique patterns. We are now able to engineer the exact temporal shape of terahertz waves – to say essentially, ‘I want a waveform that looks like this,’” said Benea-Chelmus.
“The fact that our device already makes use of a standard optical signal is really an advantage, because it means that these new chips can be used with traditional lasers, which work very well and are very well understood. It means our device is telecommunications-compatible,” she said.
Such THz PICs could play a key role in sixth generation mobile systems (6G) she says.
Quantum computers
Next, Benea-Chelmus plans to focus on tweaking the properties of the chip’s waveguides and antennas to engineer waveforms with greater amplitudes, and more finely tuned frequencies and decay rates. She also sees potential for the terahertz technology developed in her lab to be useful for quantum applications.
“There are many fundamental questions to address; for example, we are interested in whether we can use such chips to generate new types of quantum radiation that can be manipulated on extremely short timescales. Such waves in quantum science can be used to control quantum objects.”
https://doi.org/10.1038/s41467-022-35517-6
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