# On-chip microwave oscillator in deep-subwavelength scale based on spoof plasmonic skyrmions

## TL;DR

Researchers created a tiny on-chip microwave oscillator using a new design based on spoof plasmonic skyrmions, enabling extreme miniaturization of electronic circuits.

## Contribution

The first integration of electromagnetic skyrmions with active circuits in a 0.18 μm CMOS process for deep-subwavelength microwave oscillators.

## Key findings

- Achieved an electrical size of λ0/865 and a mode volume of 2.97 × 10−11 λ03.
- Used square spiral metal lines to create a spoof plasmonic skyrmion resonator functioning as both frequency selector and energy storage.
- Proposed a strongly-coupled excitation structure to concentrate electromagnetic energy efficiently.

## Abstract

Exploring wave-matter interactions at extreme electromagnetic (EM) scales has long been a focal topic in multidisciplinary research, but deep-subwavelength field localization remains a persistent challenge. Here, we demonstrate an on-chip microwave oscillator with an electrical size of λ0/865 (λ0 is the operating wavelength) and a mode volume of 2.97 × 10−11 λ03 using the 0.18 μm complementary metal-oxide-semiconductor (CMOS) process. The physical insight is based on a spoof plasmonic skyrmion resonator realized by square spiral metal lines, which simultaneously functions as a frequency selector and an energy storage element for EM signal generation. A strongly-coupled excitation structure is proposed to efficiently concentrate EM energy into the deep-subwavelength resonance structure, and a complementary cross-coupled pair is employed to compensate for the high material loss resulting from the extreme energy concentration. This work paves the way for integrating the skyrmion resonances into the CMOS chips in extremely deep-subwavelength scale, and holds great promise for miniaturized integrated circuits and systems.

This work presents the pioneering integration of electromagnetic skyrmions with active circuits in the 0.18 μm CMOS process, achieving a deep-subwavelength on-chip microwave oscillator.