In the HERCULES project, we will improve the refractive index detection limit by 3 orders of magnitude relative to the state of the art, by implementing an on-chip optical heterodyne measurement using one of the brand-new semiconductor lasers developed during the DANCER starting grant. The detection limit (DL) is the key measure of the performance of a RI sensor and determines the smallest change in refractive index that a sensor can detect. The DL is a function of the RI sensitivity, which is the magnitude in shift of the resonant wavelength versus the change in RI of the sample, and of the sensor resolution, which characterizes the smallest possible spectral shift that can be accurately measured. The laser uses a resonant mirror comprised of a 1D photonic crystal cavity. Approximately 40% of the mode supported by the 1D PhC exists in the cladding material (in this case, the air or water of the sample) meaning the lasing wavelength is strongly affected by the sample’s refractive index. The linewidth of the laser is on the order of Megahertz which is three orders of magnitude smaller than that of silicon ring resonators typically used for RI sensing.

This action supports physical and blended mobility of higher education students and staff from EU Member States and third countries associated to Erasmus+ to any country in the world. Students in all study fields and cycles can take part in a study period or traineeship abroad. Higher education teaching and administrative staff can take part in professional development activities abroad, as well as staff from the field of work in order to teach and train students or staff at higher education institutions.