Choi Hae Young, Kim Myoung Jin, Lee Byeong Ha
Opt Express. 2007 Apr 30;15(9):5711-20. doi: 10.1364/oe.15.005711.
We propose simple and compact methods for implementing all-fiber interferometers. The interference between the core and the cladding modes of a photonic crystal fiber (PCF) is utilized. To excite the cladding modes from the fundamental core mode of a PCF, a coupling point or region is formed by using two methods. One is fusion splicing two pieces of a PCF with a small lateral offset, and the other is partially collapsing the air-holes in a single piece of PCF. By making another coupling point at a different location along the fiber, the proposed all-PCF interferometer is implemented. The spectral response of the interferometer is investigated mainly in terms of its wavelength spectrum. The spatial frequency of the spectrum was proportional to the physical length of the interferometer and the difference between the modal group indices of involved waveguide modes. For the splicing type interferometer, only a single spatial frequency component was dominantly observed, while the collapsing type was associated with several components at a time. By analyzing the spatial frequency spectrum of the wavelength spectrum, the modal group index differences of the PCF were obtained from to . As potential applications of the all-PCF interferometer, strain sensing is experimentally demonstrated and ultra-high temperature sensing is proposed.
我们提出了用于实现全光纤干涉仪的简单且紧凑的方法。利用了光子晶体光纤（PCF）纤芯模式与包层模式之间的干涉。为了从PCF的基模纤芯模式激发包层模式，通过两种方法形成耦合点或区域。一种是将两段PCF以较小的横向偏移进行熔接，另一种是使单段PCF中的气孔部分塌陷。通过在沿光纤的不同位置制作另一个耦合点，实现了所提出的全PCF干涉仪。主要从波长光谱方面研究了干涉仪的光谱响应。光谱的空间频率与干涉仪的物理长度以及所涉及的波导模式的模群折射率之差成正比。对于熔接型干涉仪，仅主要观察到单个空间频率分量，而塌陷型干涉仪一次与几个分量相关联。通过分析波长光谱的空间频率光谱，获得了PCF从 到 的模群折射率差。作为全PCF干涉仪的潜在应用，通过实验证明了应变传感并提出了超高温传感。
