Temperature dependence of the zero-field splitting parameter of nitrogen-vacancy centre ensembles in diamond considering microwave and laser heating effect.

The nitrogen-vacancy (NV) centre in diamond is regarded as a promising micro-nano scale thermometer due to its high stability, good temperature resolution and its scope for integration. The relation between the zero-field splitting parameter (D) and temperature (T) is fundamental for its applications. In this work, an optical system that uses continuous-wave optically detected magnetic resonance technique for the measurement of D-T was built. The temperature measured by a home-made thermostatic system and two calibrated platinum resistance thermometers was regarded as reference. Before D was measured, microwave and laser heating effect was investigated quantitatively. The drift of D at different microwave and laser power in this system was observed. Although the dips’ contrast could be improved by higher microwave power, the heating effect was significant if the power was higher thanâ€"5 dBm. The heating effect from laser power showed a linear trend which could be corrected by an average factor of âˆ'3.69 Ă— 10^âˆ'5 GHz mW^âˆ'1. By using the optimized parameters, D was measured from 298 to 383 K. The reliability of our experimental method can be demonstrated by the good agreement between the present data and those obtained from similar samples. Our work provides a reference for similar experiments that the heating effect could not be neglected, which would be essential to obtain a more precise D-T relation when considering the NV centre as a thermometer. The inconsistency existing in the results from different groups indicates that further metrological investigations are still needed for the application of the NV centre as a practical and accurate thermometer in the near future. [ABSTRACT FROM AUTHOR]