Increased sensitivity of femtosecond laser micro-machined in-fiber Mach-Zehnder interferometer for small-scale refractive index sensing
Anna Dębowska , Marcin Koba , Monika Janik , Wojtek J. Bock , Mateusz Jakub Śmietana
AbstractIn this paper we focus on refractive index (RI) sensing properties of a micro-size In-fiber Mach-Zehnder Interferometer (μIMZI). The μIMZI structure was fabricated as a precisely controlled side opening of a single-mode fiber using a femtosecond laser. The sensitivity to RI change in the micro-cavity has been measured and two RI sensitivity regions have been found for RI 1.33-1.36 and 1.37-1.40 RIU. The sensitivity in the first region is over 12,000 nm/RIU, and in the higher RI region is close to 50% higher. The obtained structures are an excellent solution for RI sensing with negligible temperature cross-sensitivity, especially where small amounts of liquid are available, e.g. in lab-on-chip, microfluidics.
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