Stable Soliton Microcomb Generation in X-cut Lithium Tantalate via Thermal-Assisted Photorefractive Suppression

TL;DR

This paper demonstrates a novel thermal-assisted method to suppress photorefractive and thermal effects, enabling stable soliton microcomb generation in X-cut lithium tantalate microresonators for integrated photonics.

Contribution

It introduces a new thermal-regulated and laser-assisted approach to achieve stable soliton formation in X-cut lithium tantalate, overcoming previous material limitations.

Findings

Successful stabilization of soliton microcombs in X-cut lithium tantalate

Enhanced robustness of mode-locked states against perturbations

Potential for integrated photonic circuits combining Kerr nonlinearity and EO modulation

Abstract

Chip-based soliton frequency microcombs combine compact size, broad bandwidth, and high coherence, presenting a promising solution for integrated optical telecommunications, precision sensing, and spectroscopy. Recent progress in ferroelectric thin films, particularly thin-film Lithium niobate (LN) and thin-film Lithium tantalate (LT), has significantly advanced electro-optic (EO) modulation and soliton microcombs generation, leveraging their strong third-order nonlinearity and high Pockels coefficients. However, achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena. These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation. Here, following the thermal-regulated carrier behaviour and auxiliary-laser-assisted approach, we propose a convenient mechanism to suppress both photorefractive and thermal dragging effect at once, and implement a facile method for soliton formation and its long-term stabilization in integrated X-cut LT microresonators for the first time. The resulting mode-locked states exhibit robust stability against perturbations, enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.