Attosecond Resolution

Researchers demonstrate an on-chip, optoelectronic device capable of sampling arbitrary, low-energy, near-infrared waveforms under ambient conditions with sub-optical-cycle resolution. The detector uses field-driven photoemission from resonant nanoantennas to create attosecond electron bursts that probe the electric field of weak optical waveforms. Using these devices, they sampled the electric fields of ~5 fJ (6.4 MV m−1), few-cycle, near-infrared waveforms using ~50 pJ (0.64 GV m−1) near-infrared driving pulses. Beyond sampling these weak optical waveforms, our measurements directly reveal the localized plasmonic dynamics of the emitting nanoantennas in situ. Applications include broadband time-domain spectroscopy of molecular fingerprints from the visible region through the infrared, time-domain analysis of nonlinear phenomena and detailed investigations of strong-field light–matter interaction.

This work is very significant for investigating a lot of processes and technologies.

Arxiv – n-chip sampling of optical fields with attosecond resolution

Attosecond streaking spectroscopy has been used to study the role of optical-field-controlled coherent electron dynamics in the control of chemical reaction pathways and the investigation of petahertz-level electrical currents in solid-state systems. It was also recently shown that sub-cycle field sampling of the free-induction decays of biological systems can provide an order of magnitude reduction in the limits of detection and improved molecular sensitivity compared to traditional frequency-domain spectroscopic methods. Despite these compelling results, scaling such techniques into the near-IR and visible spectral regions has remained challenging. Manipulation of short electron wave packets and attosecond streaking in the visible to near-IR spectral regions have proven to be viable paths towards direct optical-field sampling in the time-domain. However, these techniques require high-energy optical sources and complicated optical apparatus, with no compact and integratable sampling technology with the bandwidth and field sensitivity required for real-world applications of interest.

To address this lack of compact and integratable tools for optical-field sampling in the visible to near-IR, researchers have developed and demonstrated an on-chip, time-domain, sampling technique for measuring arbitrary electric fields of few-fJ optical pulses in ambient conditions. The enhanced local electric field surrounding plasmonic nanostructures has been used to generate strong electric fields in nanometer sized volumes creating a new regime for exploring attosecond science. This work leverages the sub-cycle optical field emission from plasmonic nanoantennas to achieve petahertz-level sampling bandwidths using only picojoules of energy. Furthermore, by electrically connecting the nanoantenna arrays via nanoscale wires, the field samplers we demonstrate here are amenable to large-scale electronic integration.

Beyond demonstrating the feasibility of sub-cycle field sampling of petahertz-scale frequencies, this result reveals in situ dynamical properties of the interaction of the driving optical-field waveform with the plasmonic nanoantennas. This work will enable the development of new tools for optical metrology that will complement traditional spectroscopic methods and unravel linear and nonlinear light-matter interactions as they occur at their natural time and length scales.

SOURCES – Nature Photonics – On-chip sampling of optical fields with attosecond resolution, (2021). DOI: 10.1038/s41566-021-00792-0

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