Study of Spectrally Resolved Optical Waveguide Resonant Sensor Enhanced with Perovskite Thin Film

A spectrally resolved optical waveguide resonance sensor modified with perovskite film is proposed. The sensor is based on a Kretschmann configuration consisting of a coupling prism, an indium tin oxide (ITO) glass, a gold film, a mesoporous TiO2 layer, and a perovskite film. In the fabrication process, a gold film was first deposited onto the ITO glass by magnetron sputtering, followed by the deposition of a mesoporous TiO2 layer via a sol–gel method, and finally a perovskite film was prepared using a two-step process. The thicknesses of the mesoporous TiO2 and perovskite layers were measured by a scanning electron microscope. Using the measured film thicknesses, the sensor structure was simulated based on Fresnel theory, yielding the resonance spectra. The fitted resonance wavelength is in good agreement with the experimentally measured resonance wavelength, confirming the accuracy of the adopted model. To further evaluate the sensing performance, a four-layer structure (prism/Au/mesoporous TiO2/analyte) and a five-layer structure (prism/Au/mesoporous TiO2/perovskite/analyte) were employed to detect different concentrations of ammonia, ethanol, and isopropanol vapors. The experimental results demonstrate that, at an incident angle of 13°, the perovskite-modified sensor exhibits higher sensitivity toward all three vapors compared with the unmodified sensor, achieving a sensitivity of 3.584 nm/(mmol·L−1) for ethanol.