Scientists have studied the scientific principle of Laser Threshold Magnetometry (LTM) theory at length. Researchers at the Fraunhofer Institute for Applied Solid State Physics IAF have long worked to achieve the first laser threshold magnetometer. In 2022, researchers at Fraunhofer IAF demonstrated the world’s first magnetic field-dependent light amplification of NV centers. However, given the external laser source, they could not reach the laser threshold of the NV centers. Enter today.
Now, researchers combined the NV diamond with a second laser medium, a laser diode, for additional light amplification in an optical resonator, enabling the demonstration of the laser threshold for the first time.
This is important in measuring tiny magnetic fields, such as those generated by brain waves, for novel opportunities for medical diagnostics and treatment. Led by Dr. Jan Jeske at Fraunhofer IAF, the team is working on an approach to precise magnetic field measurements: Laser Threshold Magnetometry. So far, they have combined an NV diamond and a laser diode in a resonator, demonstrating the sensor system with two active media for the first time.
The basic concept is to develop a laser from NV centers and use the laser light that reacts to magnetic fields, to obtain precise information about the strength and direction of a magnetic field. As magnetic fields near the laser threshold, the point at which the laser starts or stops emitting light, there’s a very strong effect on the signal. Laser signals can be measured much more accurately and over a wider dynamic range than fluorescent light.
Quantum sensors based on diamond nitrogen-vacancy (NV) centers are currently used for precise magnetic field measurements at room temperature and in background magnetic fields. Laser Threshold Magnetometry (LTM) is a novel approach to measuring extremely low magnetic fields in the femtotesla (fT) to picotesla (pT) range, and it allows measurements with a high dynamic range without the need to suppress background fields. Laser threshold magnetometry is particularly useful for such medical applications as measuring biomagnetic signals from the brain or heart.
They published their work in Science Advances.
