Current sensor based on an integrated micro-ring resonator and superparamagnetic nanoparticles

An ultra-small integrated photonic current sensor based on a silicon micro-ring resonator (MRR) with a cladding layer of Fe3O4 superparamagnetic nanoparticles (SPNPs) is demonstrated. In the magnetic field generated by an alternating current, the Fe3O4 SPNPs lose energy and change the MRR temperature, which leads to a spectral shift in the MRR transmission. The sensor was demonstrated with good linearity in the frequency range 0–60 kHz and current amplitudes from 0 to 0.5 A. This work provides a basis for integrated micro-current sensors, and promotes the development of photoelectric sensors on silicon substrates.