Nanoantenna Design for Enhanced Carrier-Envelope-Phase Sensitivity

TL;DR

This paper explores how nanoantenna geometry and resonance tuning can significantly enhance carrier-envelope-phase detection sensitivity and signal quality in ultrafast optical applications.

Contribution

It demonstrates that specific nanoantenna design modifications can improve CEP-sensitive photocurrent and SNR by an order of magnitude, guiding future ultrafast nanoelectronics.

Findings

CEP-sensitive current improved by 5-10 times

Signal-to-noise ratio increased by 50-100 times

Design guidelines for nanoantenna optimization

Abstract

Optical-field emission from nanostructured solids such as subwavelength nanoantennas can be leveraged to create sub-femtosecond, PHz-scale electronics for optical-field detection. One application that is of particular interest is the detection of an incident optical pulse's carrier-envelope phase. Such carrier-envelope-phase detection requires few-cycle, broadband optical excitation where the resonant properties of the nanoantenna can strongly alter the response of the near field in time. Little quantitative investigation has been performed to understand how the geometry and resonant properties of the antennae should be tuned to enhance the carrier-envelope phase sensitivity and signal to noise ratio. Here we examine how the geometry and resonance frequency of planar plasmonic nanoantennas can be engineered for enhancing the emitted carrier-envelope-phase-sensitive photocurrent when driven by a few-cycle optical pulse. We find that with the simple addition of curved sidewalls leading to the apex, and proper tuning of the resonance wavelength, the net CEP-sensitive current per nanoantenna can be improved by $5$-$10\times$, and the signal-to-noise-ratio by $50$-$100\times$ relative to simple triangular antennas operated on resonance. Our findings will inform the next generation of nanoantenna designs for emerging applications in ultrafast photoelectron metrology and petahertz electronics.