Nanoantenna design for enhanced carrier-envelope-phase sensitivity

Optical-field emission from nanostructured solids such as subwavelength nanoantennas can be leveraged to create sub-femtosecond, petahertz-scale electronics for optical-field detection. One application of particular interest is the detection of an incident optical pulse's carrier-envelope phase (CEP). Such CEP 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 antennas should be tuned to enhance the CEP sensitivity and signal-to-noise ratio. Here we examine how the geometry and resonance frequency of planar plasmonic nanoantennas can be engineered to enhance the emitted CEP-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 x, and the signal-to-noise-ratio by 50-100 x 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. (C) 2021 Optical Society of America

Automated summary

Engineering the geometry and resonance frequency of planar plasmonic nanoantennas can enhance the emitted CEP-sensitive photocurrent, leading to significant improvements in CEP sensitivity and signal-to-noise ratio. By adding curved sidewalls leading to the apex and tuning the resonance wavelength, the net CEP-sensitive current per nanoantenna can be improved by 5-10 times, and the signal-to-noise ratio can be increased by 50-100 times, informing the next generation of nanoantenna designs for ultrafast photoelectron metrology and petahertz electronics applications.