We demonstrate a new type of fiber in-line Mach–Zehnder interferometer (MZI). The device is fabricated by firstly inscribing a ring structure surrounding the fiber core at the ends of two single-mode fibers using a femtosecond laser micromachining technique and then fusion-splicing the two fibers with end structures. Due to the high temperature produced in the fusion splicing process, the ring structure expands rapidly and results in an inner air-cavity with a suspended fiber-core. The incident light traveling in the fiber core is split into two parts at the edge of the inner air-cavity, one propagating through the air cavity while the other remains traveling along the suspended fiber core; both are collected by the fiber core at the air-cavity end, thus forming an in-line MZI. The device has good high-temperature sustainability up to 900 °C. Moreover, by drilling a hole on top of the air-cavity, an open micro-channel can be created for air pressure measurement with a pressure s...

中文翻译：

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基于带有悬浮纤维芯的气腔的光纤在线干涉仪

我们演示了一种新型的光纤在线马赫曾德尔干涉仪（MZI）。该设备的制造方法是，首先使用飞秒激光微加工技术在两个单模光纤的末端刻上一个围绕光纤纤芯的环形结构，然后将两个光纤与末端结构熔接在一起。由于熔接过程中产生的高温，环形结构迅速膨胀，并导致内部空气腔带有悬浮的纤维芯。在纤芯中传播的入射光在内部空气腔的边缘分成两部分，一个通过空气腔传播，而另一部分仍沿悬挂的纤芯传播。两者都通过位于气腔末端的纤芯收集，从而形成直列式MZI。该器件在高达900°C的温度下具有良好的高温可持续性。