Cost-Effective Mach-Zehnder Interferometer Liquid Refractive Index Sensor Based on Conventional Polymer Strip Waveguide

We propose and demonstrate a cost-effective liquid refractive index (RI) sensor in polymer materials by employing Mach-Zehnder interferometer (MZI) formed with the conventional strip waveguide. The proposed can attain high sensitivity choosing suitable reference arm length to reduce optical path difference (OPD) between two arms of employed MZI. Our fabricated devices, which have same sensing 7900 µm but different lengths 7900.0, 7942.5, 7950.9, 7962.2, 7969.5 µm, respectively, exhibit maximum RI sensitivities 33662.8 nm/RIU, almost detection range (DR) 0.0041 ± 0.0002 RIU.