Scientists use new integrated photonic circuit chips to reduce the "terahertz gap"

Recently, foreign research teams announced the development of an extremely thin chip with integrated photonic circuits - when connected to a laser beam, this new thin film circuit can generate a tunable terahertz frequency wave, so as to use the so-called "terahertz gap" (Terahertz Gap, located between 0.3-30 terahertz in the electromagnetic spectrum) for spectral analysis and imaging.

It is reported that processing this gap is still a dead zone. Its frequency is too fast for today's electronic and telecommunication equipment, but too slow for optical and imaging applications.

However, the new chip made by scientists has been able to generate terahertz wave with customized frequency, wavelength, amplitude and phase. This precise control further promotes the application of terahertz radiation in the next generation of electronic and optical fields.

(Image source: EPFL)

This research was jointly carried out by EPFL, ETH Zurich and Harvard University in Lausanne, Switzerland, and its results have been published in Nature Communications.

Cristina Benea-Chelmus, who led the research of the Hybrid Photonics Laboratory (HYLAB) of the EPFL School of Engineering, explained that although scientists had successfully generated terahertz waves in the laboratory environment before, the previous methods mainly relied on block crystals to generate the correct frequency.

On the contrary, her laboratory used a photonic circuit made of lithium niobate, and Harvard collaborators carefully etched it on a nanometer scale, which made the method simpler. The use of silicon substrate also makes the device suitable for integration into electronic and optical systems.

She explained: "It is very challenging to generate waves at very high frequencies. Few technologies can produce unique patterns. We can now design the exact time shape of terahertz waves - essentially, I want a waveform like this."

In order to achieve this goal, Benea-Chelmus's laboratory designed the channel arrangement of the chip, called wave guides. In this way, micro-antennas can be used to transmit terahertz waves generated by optical fibers.

Benea-Chelmus stressed: "In fact, our equipment has used standard optical signals, which is really an advantage, because it means that these new chips can be used with traditional lasers. These lasers work very well and are very easy to understand. This means that our equipment is compatible with the telecommunication communication function." She added that the miniaturized equipment that transmits and receives signals in the terahertz range, It may play a key role in the sixth generation mobile system (6G).

In the field of optics, Benea-Chelmus believes that miniaturized lithium niobate chips have special potential in spectroscopy and imaging. In addition to the non-ionizing characteristics, the energy of terahertz wave is much lower than that of many other types of wave (such as X-ray) currently used to provide material composition information. Therefore, compact and non-destructive devices such as lithium niobate chips can provide a less invasive method to replace the current spectral technology.

Next, Benea-Chelmus plans to focus on adjusting the characteristics of chip waveguides and antennas to design waveforms with larger amplitudes and more precisely tuned frequencies and attenuation rates. She also saw the potential of terahertz technology developed by her laboratory in quantum applications. She said that there are still many basic problems to be solved when the chip is put into practical application. For example, whether this chip can be used to generate new quantum radiation in the future and operate on a very short time scale.

Source: OFweek