Random laser-based noninvasive sensor for direct measurements of scattering samples

The invention of the random laser has opened a new frontier in optics, providing also the opportunity to explore new possibilities in the eld of sensing. The research in optical sensors has indeed been largely encouraged by the demand for low-cost and non-invasive new detection strategies. The main advantage in exploiting the physical principle of the random laser in optical sensors is due to the presence of the stimulated emission mechanism, which allows ampli cation and spectral modi cation of the signal. We present here a step forward in the exploitation of this optical sensor device by an improved revisitation of a previous experimental setup, both in the instrumentation and in the measurement method, to mitigate the instability of the results due to shot-to-shot pump energy uctuations. The novelties introduced, the use of optical bers, a reference sensor, and a peristaltic pump have shown to eliminate optical beam alignment issues and the problems linked to variation in pump energy. The implemented sensor allows easy and rapid change of the sensed medium. These results pave the way for a portable device to directly measure the scattering of liquid samples, without resorting to complicated numerical or analytic inversion procedures of the measured data, provided that a suitable calibration of the system is performed. SPIEDigitalLibrary.org/conference-proceedings-of-spie