German physicists boost diamond sensor sensitivity using laser cavities

Physicists in Germany have developed a new technique to probe the spin states of nitrogen-vacancy centers in diamond, Physics World reported. The research team was led by Florian Schall at the Fraunhofer Institute for Applied Solid State Physics. The method measures changes in infrared laser intensity when nitrogen-vacancy doped diamond is placed inside a laser cavity. [1]

Nitrogen-vacancy centers are point defects in the crystal lattice of diamond. They occur where an adjacent pair of carbon atoms is replaced by a single nitrogen atom and a lattice vacancy. Previous studies probed these defects using a fluorescence-based approach, but the new laser cavity system achieves 100 percent optical contrast. [1]

The development builds on decades of light amplification research. The first functional laser was demonstrated in May 1960 by Theodore Maiman at Hughes Research Laboratories using a synthetic ruby crystal pumped by a flashlamp. Lasers evolved from theoretical maser concepts, which amplified microwave radiation through stimulated emission. [2][3]

The higher contrast achieved by measuring infrared laser intensity within the cavity significantly improves measurement sensitivity. According to Physics World, this advance could make nitrogen-vacancy centers a much more competitive option for sensing subtle magnetic fields. [1]