直接熔融塌陷光子晶体光纤马赫-曾德尔干涉仪的折射率传感特性

Refractive Index Sensing Characteristics of a Mach-Zehnder Interferometer Based on Directly Photonic Crystal Fiber

研制了一种直接熔融塌陷锥形光子晶体光纤（PCF）马赫一曾德尔干涉仪（MZI）传感器，它是通过电弧放电的方法使光子晶体光纤空气孔受热塌陷，从而直接在光子晶体光纤上形成一个锥区制作而成的，可通过控制电弧参数以及放电次数来灵活控制锥区结构。研究了不同锥区长度下的输出光谱及其传输光谱随外界（RI）折射率的变化关系。实验结果表明，随着锥区长度的增加，在整个波长范围内MZI输出光谱的自由光谱区减小，且自由光谱区在1554．34nm波长附近由33．38nm减小到7．86nm。在1．3414~1．3862折射率变化范围内，该传感器的折射率测量灵敏度可达276．38nm／RIU（RIU为折射率单位）。

Based on a directly melting-collapsed tapered photonic crystal fiber （PCF）, a novel Mach-Zehnder interferometer （MZI） sensor is proposed. The taper region is formed directly by arc discharge. By controlling the parameters and times of arc discharge, the taper geometry can be flexibly controlled. The output spectra under different taper lengths are discussed, and the relationship between the wavelength shifts and the refractive index（RI） is investigated. Experimental results show that with the increase of taper length, the free spectral range of MZI output spectrum decreases in the whole wavelength range, and decreases from 33. 38 nm to 7. 86 nm nearby 1554.34 nm. When the RI ranges from 1. 3414 to 1. 3862, the refractive index sensitivity of the sensor reaches 276.38 nm/RIU （RIU is refractive index unit）.