Oscillator-based solid-state spin sensor

We have developed a high-performance, low-volume, low-weight, and low-power sensor based on a self-sustaining oscillator. The techniques described here may be used for sensing various fields; we demonstrate magnetic sensing. The oscillator is based on a dielectric resonator that contains paramagnetic defects and is connected to a sustaining amplifier in a feedback loop. The resonance frequency of the dielectric resonator shifts in response to changes in the magnetic field, resulting in a shift in the frequency of the self-sustaining oscillator. The value of the magnetic field is thereby encoded in the shift or modulation output of the self-sustaining oscillator. The sensor as demonstrated uses no optics, no input microwaves, and, not including digitization electronics, consumes less than 300 mW of power and exhibits a sensitivity at or below tens of pT/√{square root over (Hz)}. In some implementations, the sensor is less than 1 mL in volume.