马明敏
荐读:Performance optimization of planar photonic crystal...
2025-5-7 13:24
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RESEARCH ARTICLE

Performance optimization of planar photonic crystal bound states in the continuum cavities: mitigating finite-size effects  

Ran Hao, Bilin Ye, Jinhong Xu, Yonggang Zou

2025, 18(1): 3.https://doi.org/10.1007/s12200-025-00147-5

AbstractBound states in the continuum (BICs) offer a promising solution to achieving high-quality factor (Q factor) cavities. However, finite-size effects severely deteriorate the BIC mode in practical applications. This paper reports the experimental demonstration of an electrically pumped 940 nm laser based on optimized BIC cavity, achieving a high Q factor of up to 1.18 × 104 even with finite photonic crystal footprint, which is two orders of magnitude larger than un-optimized BIC design. Two strategies have been systematically investigated to mitigate finite-size effects: reflective photonic crystal cavity design and graded photonic crystal cavity design. Both methods significantly improve the Q factor, demonstrating the effectiveness of preserving BIC characteristics in finite-sized photonic crystal cavities. In addition, the reflective boundary photonic crystal design is fabricated and experimentally characterized to demonstrate its lasing characteristics. The fabricated laser exhibits single-mode operation with a signal-to-noise ratio of 38.6 dB. These results pave the way for future designs of BICs with finite size in real applications, promoting the performance of BIC-based integrated lasers.

研究背景

光子晶体腔因其高度可调控的腔行为而备受关注,但传统光子晶体激光器难以同时实现高Q值、窄线宽和高输出功率。近年来,基于束缚态在连续体(BIC)的光子晶体激光器因其理论上无限大的Q值而受到关注,然而实际应用中有限尺寸的光子晶体会严重破坏BIC模式,导致Q值大幅下降。

主要内容

本文研究了如何在有限尺寸的光子晶体中优化BIC腔的性能,以实现高Q值激光器。研究提出了两种策略:反射光子晶体腔设计和渐变光子晶体腔设计,并通过实验验证了这些设计的有效性。实验中展示了基于BIC940 nm电泵浦激光器,实现了高达1.18×10Q值,比未优化时高出两个数量级。

方法

1. 垂直腔激光器设计:采用分布式布拉格反射镜(DBR)实现激光发射,P型和NDBR镜分别位于顶部和底部,通过设计P-DBR镜的反射率低于N-DBR镜,实现激光从P-DBR表面单向发射。

2. 工艺方案:采用三步对准电子束光刻工艺,首先定义并蚀刻台面图案,随后精确对准并蚀刻光子晶体图案,最后进行电极图案化;通过优化反应离子蚀刻(RIE)参数,确保精确控制空气孔的尺寸和侧壁轮廓,这对于维持高Q值性能至关重要。

创新点

1. 首次实验展示:首次实现了基于BIC940 nm电泵浦激光器,填补了该波段电泵浦BIC激光器的空白。

2. 反射光子晶体设计:通过在BIC光子晶体周围添加反射光子晶体,利用其带隙特性反射BIC模式,减少边界截断效应,Q值提升至13,974

3. 渐变光子晶体设计:通过逐渐改变空气孔半径,创建平滑的模式过渡区,减少模式截断和辐射损耗,Q值最高可达92,091

4. 高性能验证:实验验证的激光器展现出单模运行,信噪比高达38.6 dB,证明了设计的实用性。

总结

本研究通过创新的光子晶体设计,成功克服了BIC在有限尺寸光子晶体中的限制,为高性能BIC激光器的设计提供了新思路,推动了BIC技术在光子集成领域的应用前景。

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链接地址:https://wap.sciencenet.cn/blog-586493-1484784.html?mobile=1

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