Schematic of the microrefractometer. The incident light passing through the fiber is diffracted by the end-facet transmission grating. The zeroth and ± first order diffracted light beams crossing the microfluidic channel are collected by the fibers on the right side and analyzed by a spectrometer.
Schematic of the fabrication process of fiber end facet grating structures (a) and scanning electron microscopy image of a fabricated end facet grating ( line and space) (b).
Spectra of the zeroth and first diffraction orders, showing two peak wavelengths which are slightly different.
Measured intensities of the zeroth (a) and the first (b) order diffraction light beam with samples of different sucrose concentration. (c) shows the deduced linear relationship between the measured intensity and refractive index of the sample.
(a) Absorption spectrum of the 25% sucrose solution with and without R6G. (b) Variation in the measured light intensity at 532 and 700 nm wavelengths.
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