Low phase noise THz generation from a fiber-referenced Kerr microresonator soliton comb

TL;DR

This paper demonstrates a low phase noise THz wave at approximately 560 GHz generated using a fiber-referenced Kerr microresonator soliton comb, with improved phase noise performance over existing photonic THz oscillators.

Contribution

It introduces a novel method of stabilizing a Kerr microresonator soliton comb with a fiber reference to produce low phase noise THz signals and a technique to measure phase noise beyond traditional limits.

Findings

Achieved a THz wave with low phase noise at 560 GHz.

Demonstrated phase noise surpassing other photonic THz oscillators (> 300 GHz).

Developed a measurement technique for phase noise characterization beyond conventional limits.

Abstract

THz oscillators generated via frequency-multiplication of microwaves are facing difficulty in achieving low phase noise. Photonics-based techniques, in which optical two tones are translated to a THz wave through opto-electronic conversion, are promising if the relative phase noise between the two tones is well suppressed. Here, a THz ($\approx$ 560 GHz) wave with a low phase noise is provided by a frequency-stabilized, dissipative Kerr microresonator soliton comb. The repetition frequency of the comb is stabilized to a long fiber in a two-wavelength delayed self-heterodyne interferometer, significantly reducing the phase noise of the THz wave. A measurement technique to characterize the phase noise of the THz wave beyond the limit of a frequency-multiplied microwave is also demonstrated, showing the superior phase noise of the THz wave to any other photonic THz oscillators (> 300 GHz).