Ignacio Raúl Matías Maestro

Optimization in nanocoated D-shaped optical fiber sensors

Nanocoated D-shaped optical fibers have been proven as effective sensors. Here, we show that the full width at half minimum (FWHM) of lossy mode resonance can be reduced by optimizing the nanocoating width, thickness and refractive index. As a counterpart, several resonances are observed in the optical spectrum for specific conditions. These resonances are caused by multiple modes guided in the nanocoating. By optimizing the width of the coating and the imaginary part of its refractive index, it is possible to isolate one of these resonances, which allows one to reduce the full width at half minimum of the device and, hence, to increase the figure of merit. Moreover, it is even possible to avoid the need of a polarizer by designing a device where the resonance bands for TE and TM polarization are centered at the same wavelength. This is interesting for the development of optical filters and sensors with a high figure of merit.

Rum adulteration detection using an optical fiber sensor based on multimodal interference (MMI)

In this work, we propose and demonstrate the fabrication of an optical fiber sensor based on multimode interference effects (MMI) for rum quality control. The operation of the sensor relies on the fact that when rum is adulterated, which can be done either with ethanol or ethylene glycol, the refractive index (RI) of the adulterated rum will be different as compared to the original rum. Since the white rum (Bacardi®) has a RI close to 1.345 and the highest RI of the contaminant is 1.412 (ethylene glycol), the RI of the adulterated rum will increase as the volume of the contaminant is increased. Therefore, considering that the MMI sensor exhibits a sensitivity of 258.06 nm/RIU for liquids with RI ranging from 1.318 to 1.4203, we can accurately determine if a rum sample is free of contaminants or adulterated with other liquid, which is typically performed using ethanol or toxic elements like ethylene glycol. Although the sensor cannot determine which kind of liquid is altering the rum, it can easily detect when the original rum has been adulterated, even with small amounts of liquid. The sensor also provides high repeatability and reversibility while using a fast and simple fabrication process.