Lightwave electronics is an emerging field that aims to integrate optical and electronic systems at incredibly high speeds. The key idea is to harness the electric field of light waves, which oscillate on sub-femtosecond timescales, to directly drive electronic processes. This allows for the processing and manipulation of information at speeds far beyond what is possible with current electronic technologies.

A research team from MIT demonstrated a lightwave-electronic mixer at petahertz (PHz)-scale frequencies, creating a first step toward making communication technology faster. The technology may also progress research toward developing new, miniaturized lightwave-electronic circuitry capable of handling optical signals directly at the nanoscale.

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The chip-scale, lightwave-electronic mixer is depicted at petahertz-scale frequencies. The researchers believe the device will lead to the advancement of communications technologies and developing nanoscale lightwave-electronic circuitry for transmitting optical signals. Courtesy of Sampson Wilcox/Research Laboratory of Electronics.

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Operating beyond 0.35 PHz, the mixer uses tiny nanoantennae which can mix different frequencies of light, enabling analysis of signals oscillating orders of magnitude faster than the fastest accessible to conventional electronics. The team’s study highlights the use of nanoantenna networks to create a broadband, on-chip electronic optical frequency mixer that allows for the accurate readout of optical wave forms spanning more than one octave of bandwidth. Importantly, this process worked by using a commercial turnkey laser that can be purchased off the shelf, rather than a highly customized laser.

While optical frequency mixing is possible using nonlinear materials, the process is purely optical. Furthermore, the materials have to be many wavelengths in thickness, limiting the device size to the micrometer scale. In contrast, the lightwave-electronic method demonstrated by the authors uses a light-driven tunneling mechanism that offers high nonlinearities for frequency mixing and direct electronic output using nanometer-scale devices.

While this study focused on characterizing light pulses of different frequencies, the researchers envision that similar devices will enable one to construct circuits using light waves. This device, with bandwidths spanning multiple octaves, could provide new ways to investigate ultrafast light-matter interactions, accelerating advancements in ultrafast source technologies. While those devices are still in development, the researchers at present see the potential for the mixer to create new technologies and applications in fields like spectroscopy, imaging, and communications, advancing the ability to explore and manipulate the ultrafast dynamics of light.

The research was published in Science Advances (www.doi.org/10.1126/sciadv.adq0642).

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