Moon Sucbei, Chen Zhongping
Department of Physics, Kookmin University, Seoul 136-702, South Korea.
Appl Opt. 2012 Dec 1;51(34):8262-70. doi: 10.1364/AO.51.008262.
We have investigated the use of multimode fiber in optical coherence tomography (OCT) with a mode filter that selectively suppresses the power of the high-order modes (HOMs). A large-core fiber (LCF) that has a moderate number of guiding modes was found to be an attractive alternative to the conventional single-mode fiber for its large mode area and the consequentially wide Rayleigh range of the output beam if the HOMs of the LCF were efficiently filtered out by a mode filter installed in the middle. For this, a simple mode filtering scheme of a fiber-coil mode filter was developed in this study. The LCF was uniformly coiled by an optimal bend radius with a fiber winder, specially devised for making a low-loss mode filter. The feasibility of the mode-filtered LCF in OCT imaging was tested with a common-path OCT system. It has been successfully demonstrated that our mode-filtered LCF can provide a useful imaging or sensing probe without an objective lens that greatly simplifies the structure of the probing optics.
我们研究了在光学相干断层扫描（OCT）中使用多模光纤，并配备了一个模式滤波器，该滤波器可选择性地抑制高阶模（HOMs）的功率。如果通过安装在中间的模式滤波器有效滤除大芯光纤（LCF）的高阶模，那么这种具有适度数量导模的大芯光纤因其大模面积以及相应的输出光束宽瑞利范围，被发现是传统单模光纤的一个有吸引力的替代方案。为此，本研究开发了一种简单的光纤线圈模式滤波器的模式滤波方案。通过专门设计用于制造低损耗模式滤波器的光纤绕线器，以最佳弯曲半径对大芯光纤进行均匀缠绕。利用共光路OCT系统测试了经模式滤波的大芯光纤在OCT成像中的可行性。已经成功证明，我们经模式滤波的大芯光纤可以提供一种有用的成像或传感探头，无需物镜，这极大地简化了探测光学系统的结构。
