Globally stable microresonator Turing pattern formation for coherent high-power THz radiation on-chip

TL;DR

This paper introduces a novel scheme for achieving globally stable Turing pattern formation in microresonators, enabling high-power, coherent THz radiation on-chip with record efficiency and stability, suitable for advanced technological applications.

Contribution

The authors demonstrate a new method incorporating local mode hybridizations to stabilize Turing patterns, resulting in high-power, tunable, and coherent THz generation on-chip.

Findings

Achieved 45% power conversion efficiency in Turing patterns.

Demonstrated tunability across 430 GHz on a THz carrier.

Transferred Turing pattern coherence to THz radiation with high stability.

Abstract

In nonlinear microresonators driven by continuous-wave (cw) lasers, Turing patterns have been studied in the formalism of Lugiato-Lefever equation with emphasis on its high coherence and exceptional robustness against perturbations. Destabilization of Turing pattern and transition to spatio-temporal chaos, however, limits the available energy carried in the Turing rolls and prevents further harvest of their high coherence and robustness to noise. Here we report a novel scheme to circumvent such destabilization, by incorporating the effect of local mode hybridizations, and attain globally stable Turing pattern formation in chip-scale nonlinear oscillators, achieving a record high power conversion efficiency of 45% and an elevated peak-to-valley contrast of 100. The stationary Turing pattern is discretely tunable across 430 GHz on a THz carrier, with a fractional frequency sideband non-uniformity measured at 7.3x10^-14. We demonstrate the simultaneous microwave and optical coherence of the Turing rolls at different evolution stages through ultrafast optical correlation techniques. The free running Turing roll coherence, 9 kHz in 200 ms and 160 kHz in 20 minutes, is transferred onto a plasmonic photomixer for one of the highest power THz coherent generation at room-temperature, with 1.1% optical-to-THz power conversion. Its long-term stability can be further improved by more than two orders of magnitude, reaching an Allan deviation of 6x10^-10 at 100 s, with a simple computer-aided slow feedback control. The demonstrated on-chip coherent high-power Turing-THz system is promising to find applications in astrophysics, medical imaging, and wireless communications.