Fig. 4. Magnetic field–dependent amplification with ultrahigh contrast.
(A) Detection of the transmitted cavity power over the relative mirror position. The transmission of only the red laser (Seed) is not influenced when a strong magnet is brought close to the diamond (Seed + magnet). Strong amplification of the mode appears when the green laser pumps the NV centers (Seed + pump). Bringing a magnet close to the diamond substantially reduces the amplified signal (Seed+ pump + magnet). The power for the seed and pump laser is P710 = 0.3 W and P532 = 1.37 W, respectively. The data are shifted horizontally for clarity. (B) Contrast of the detected amplitude over the pump P532 and seeding P710 power. (C) Transmitted peak amplitude (det1) of the cavity mode Acavity and laterally emitted PL (det3) are detected simultaneously over time. When the magnet is brought close to the diamond for 30 s, both signals decrease. (D) Measurement of the reflected (det2) and transmitted (det1) amplitudes in absolute values with (Amag) and without (A) magnet over the pump power P532 (note the subdivided vertical axis). The seeding power is set to P710 = 1.14 W. The data represent the mean value of eight measurements.