Abstract
Sensing electric fields with high sensitivity, high spatial resolution, and at radio frequencies can be challenging to realize. Recently, point defects in silicon carbide have shown their ability to measure local electric fields by optical conversion of their charge state. Here, we report the combination of heterodyne detection with charge-based electric field sensing, solving many of the previous limitations of this technique. Owing to the nonlinear response of the charge conversion to electric fields, the application of a separate “pump” electric field results in a detection sensitivity as low as 1.1 (V/cm)/Hz, with a near-diffraction limited spatial resolution and tunable control of the sensor dynamic range. In addition, we show both incoherent and coherent heterodyne detection, allowing measurements of either unknown random fields or synchronized fields with higher sensitivities. Finally, we demonstrate in-plane vector measurements of the electric field by combining orthogonal pump electric fields. Overall, this work establishes charge-based measurements as highly relevant for solid-state defect sensing.
Highlights
It has been shown that the charge stability of defects can be used to measure radio frequency electric fields using divacancies and silicon vacancies in silicon carbide (SiC)
Electrometry by Optical Charge Conversion (EOCC) exhibits a nonlinear response to the electric field, very similar to that of a power photodetector in optics or a mixer in electronics. This implies that the variety of heterodyne techniques19,20 developed in these systems applies to EOCC, enabling improvements in sensitivity and a range of additional tools for sensing radio frequency electric fields
Heterodyne measurements would solve the main limitations of EOCC, such as a nonlinear response to electric field, limited frequency resolution, and the absence of directionality
Summary
It has been shown that the charge stability of defects can be used to measure radio frequency electric fields using divacancies and silicon vacancies in silicon carbide (SiC).11 This technique, called Electrometry by Optical Charge Conversion (EOCC), consists of optically controlling the defect’s charge state between two configurations with different photoluminescence intensities. We report the combination of heterodyne detection with charge-based electric field sensing, solving many of the previous limitations of this technique.
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