Four-wave mixing-based photonic crystal fiber microfluid sensor with embedded U-shape microslits

In this paper, we propose a four-wave mixing-based photonic crystal fiber (PCF) microfluid sensor, and two U-shape microslits fabricated by a femtosecond laser are embedded into the sensor for real-time microfluid measurement. Theoretical and experimental results prove that the signal wavelength is sensitive to both the refractive index (RI) and the material dispersion property of the liquid sample filled into the air channels. For different aqueous target samples at low concentrations, the responses of signal wavelength are consistent with each other. The obtained RI sensitivity is approximately 881.36 nm/RIU, and the sensing resolution is around 1.6 x 10(-4) RIU. The proposed sensor also shows a better figure of merit (FOM) as high as 313.65 RIU-1 when compared with the fiber SPR sensors. Besides, the signal wavelengths present different responses with the increasing aqueous concentration due to the separated dispersion characteristics of the filled liquid samples, which can be potentially applied for the discrimination of liquid samples with a well-designed wavelength-coded sensor array in the future. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The paper presents a four-wave mixing-based photonic crystal fiber microfluid sensor with U-shape microslits fabricated by a femtosecond laser for real-time microfluid measurement. The signal wavelength is sensitive to both the refractive index and material dispersion property of the liquid sample, showing potential for discrimination of liquid samples with a well-designed wavelength-coded sensor array. The proposed sensor demonstrates high sensitivity and resolution, as well as a better figure of merit compared to fiber SPR sensors.