Fluorescent nanodiamonds as quantum sensors: effects of infrared illumination

Nitrogen-vacancy (NV) centers in nanodiamonds (NDs) have emerged as powerful quantum sensors, with diverse capabilities in nano-scale sensing of physical quantities (like temperature, magnetic or electric fields), even in the fluidic medium. We, in this work, study the effects of continuous infrared (IR) illumination on ND photoluminescence (Pl) and the simultaneous effects on the contrast in optically detected magnetic resonance (ODMR) signal. Our study suggests a similar decreasing trend in both the Pl and the ODMR contrast with increasing IR powers. The dependence of ODMR contrast on IR power is seen to be more sensitive and robust. Simultaneous NV-based temperature measurements on the NDs showed no substantial change in temperature. This further indicates that such quenching effects are not a result of the heating of the NDs.