Directly accessing octave-spanning dissipative Kerr soliton frequency combs in an AlN microring resonator

TL;DR

This paper demonstrates an octave-spanning dissipative Kerr soliton frequency comb in an aluminium nitride microresonator with simplified control, broad spectral coverage, and stable operation, advancing integrated photonics applications.

Contribution

It introduces a novel AlN microresonator design enabling stable, octave-spanning DKSs with simplified pump tuning and thermal management, unlike previous silicon nitride-based systems.

Findings

Achieved octave-spanning DKS with 1100-2300 nm bandwidth

Demonstrated stable single soliton operation with a record step (~80 pm)

Simplified DKS generation without elaborate wavelength or power stabilization schemes

Abstract

Self-referenced dissipative Kerr solitons (DKSs) based on optical microresonators offer prominent characteristics including miniaturization, low power consumption, broad spectral range and inherent coherence for various applications such as precision measurement, communications, microwave photonics, and astronomical spectrometer calibration. To date, octave-spanning DKSs with a free spectral range (FSR) of ~1 THz have been achieved only in ultrahigh-Q silicon nitride microresonators, with elaborate wavelength control required. Here we demonstrate an octave-spanning DKS in an aluminium nitride (AlN) microresonator with moderate loaded Q (500,000) and FSR of 374 GHz. In the design, a TE00 mode and a TE10 mode are nearly degenerate and act as pump and auxiliary modes. The presence of the auxiliary resonance balances the thermal dragging effect in dissipative soliton comb formation, crucially simplifying the DKS generation with a single pump and leading to a wide single soliton access window. We experimentally demonstrate stable DKS operation with a record single soliton step (~80 pm) and octave-spanning bandwidth (1100-2300 nm) through adiabatic pump tuning and on-chip power of 340 mW. Our scheme also allows for direct creation of the DKS state with high probability and without elaborate wavelength or power schemes being required to stabilize the soliton behavior.