中文 |

Zigzag-shaped Tapered Optical Microfibers Interferometer Operated at Dispersion Turning Point was Invented

Author: ZHOU Wenchao |

The dispersion turning point (DTP) in microfibers has proven to be an effective exceptional phenomenon for sensitivity improvement. In order to break the adiabaticity condition and excite higher-order modes effectively to satisfy the condition of DTP, the transition segments of tapered optical microfiber should be abrupt.

Recently, a research group led by Prof. WU Yihui from Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS) proposed a zigzag-shaped optical microfiber (Z-OMF) interferometer working at the DTP. This study is published in Optical Express.

The Z-OMF was fabricated in a controllable manner by applying a slight tilt angle to the optical fiber. For a Z-OMF, the asymmetric taper structure favored the excitation of the HE11 and HE21 modes. The beating between HE11 and HE21 modes occured when they traveled along the Z-OMF optical path. When the bending angle of the Z-OMF reached 1.61°, high contrast interference fringes were formed between the HE11 and the HE21 modes.

Fig 1. Schematic diagram of the Z-tapered optical microfiber sensor (Image by WEI)

By optimizing the diameter of the OMF, the group effective refractive index (RI) difference between HE11 and HE21 mode equaled zero, satisfying the condition of dispersion turning point. At the optical fiber diameter of 2.3μm, the DTP was located at near 1300nm, and the RI sensitivity was1.46×105 ± 0.09×105 nm/RIU.

Compared with the tapered optical microfiber, straight conical fiber, the proposed Z-OMF is easier to obtain the condition of the DTP. The ultra-high RI sensitivity indicated that Z-OMF is a promising platform for chemical and biological sensing applications.

Contact

WU Yihui

Changchun Institute of Optics, Fine Mechanics and Physics

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