Abstract: A substrate comprising diamond has NV- centers in a concentration greater than about 0.5 parts per million (ppm). The method for producing this diamond substrate includes providing diamond being doped with nitrogen, irradiating at least a partial surface of the substrate with radiation that creates vacancies in the diamond, and carrying out a second heat treatment of the substrate at a certain temperature.

Abstract: A magneto-encephalography device including a plurality of laser threshold magnetometers for measuring a magnetic field is provided. Each laser threshold magnetometer includes an optical cavity, a laser medium which together with the optical cavity has a laser threshold; a laser pump; and a radio-frequency (RF) drive applied to the laser medium at or around a particular resonance frequency which varies depending on the magnetic field, such that depending on the value of the physical parameter, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output, wherein the intensity of the laser output provides a measurement of the magnitude of the magnetic field; wherein the laser threshold magnetometers are configured to be placed on a head of a subject to be monitored.

Abstract: In general, techniques of this disclosure are directed to a sensor for measuring an external magnetic field. The sensor an optical cavity, a laser medium which together with the optical cavity has a laser threshold, a laser pump, and a radio-frequency (RF) drive applied to the laser medium, such that the laser threshold varies with a change in the external magnetic field. The RF drive may be applied to the laser medium at or around a particular resonance frequency which varies depending on the external magnetic field, such that depending on the value of the external magnetic field, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output. Further, the intensity of the laser output may provide a measurement of the value of the external magnetic field.

Abstract: A magneto-encephalography device including a plurality of laser threshold magnetometers for measuring a magnetic field is provided. Each laser threshold magnetometer includes an optical cavity, a laser medium which together with the optical cavity has a laser threshold; a laser pump; and a radio-frequency (RF) drive applied to the laser medium at or around a particular resonance frequency which varies depending on the magnetic field, such that depending on the value of the physical parameter, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output, wherein the intensity of the laser output provides a measurement of the magnitude of the magnetic field; wherein the laser threshold magnetometers are configured to be placed on a head of a subject to be monitored.

Abstract: In general, techniques of this disclosure are directed to a sensor for measuring an external magnetic field. The sensor an optical cavity, a laser medium which together with the optical cavity has a laser threshold, a laser pump, and a radio-frequency (RF) drive applied to the laser medium, such that the laser threshold varies with a change in the external magnetic field. The RF drive may be applied to the laser medium at or around a particular resonance frequency which varies depending on the external magnetic field, such that depending on the value of the external magnetic field, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output. Further, the intensity of the laser output may provide a measurement of the value of the external magnetic field.