Chen Pengcheng, Shu Xuewen, Sugden Kate
Opt Lett. 2017 Oct 15;42(20):4059-4062. doi: 10.1364/OL.42.004059.
Optical Mach-Zehnder interferometers (MZIs) are useful components in a variety of optical applications, including optical modulation; signal processing; and physical, chemical, and biological sensing. We introduce here a novel, assembly-free all-in-fiber-core MZI, which is directly written with a femtosecond laser. By introducing a positive refractive index-modified zone in half of the fiber core, the original single-mode fiber section is converted into a few-mode fiber section, where a strong coupling between the two lowest-order guided modes is generated, resulting in a well-defined interference spectrum in transmission. This device promises many significant advantages over existing approaches such as ease of fabrication, stability, small insertion loss, robustness extremely broad operating bandwidth, and precise and controllable cavity lengths. These advantages make this device strikingly attractive with the potential for extensive adoption in fiber communications, signal processing, sensors, and laser wavelength control.
光学马赫-曾德尔干涉仪（MZIs）是各种光学应用中的有用组件，包括光调制、信号处理以及物理、化学和生物传感。我们在此介绍一种新型的、无需组装的全光纤纤芯MZI，它是用飞秒激光直接写入的。通过在光纤纤芯的一半区域引入正折射率改性区，原来的单模光纤段被转换为少模光纤段，在该区域两个最低阶导模之间会产生强耦合，从而在传输中产生明确的干涉光谱。与现有方法相比，该器件具有许多显著优点，如易于制造、稳定性好、插入损耗小、坚固耐用、工作带宽极宽以及腔长精确可控。这些优点使得该器件极具吸引力，有可能在光纤通信、信号处理、传感器和激光波长控制等领域得到广泛应用。
