We investigate the effect of nitrogen-vacancy (NV) centers in single crystal diamond on nonlinear optical effects using 40 fs femtosecond laser pulses. The near infrared femtosecond pulses allow us to study purely nonlinear optical effects, such as optical Kerr effect (OKE) and two-photon absorption (TPA), relating to unique optical transitions by electronic structures with NV centers. It is found that both the nonlinear optical effects are enhanced by the introduction of NV centers in the N
+ dose levels of 2.0$\times
10^{11}$ and 1.0$\times
10^{12}$ N
+/cm
2. In particular, our data demonstrate that the OKE signal is strongly enhanced for the heavily implanted type-IIa diamond. We suggest that the strong enhancement of the OKE is possibly originated from cascading OKE, where the high-density NV centers effectively break the inversion symmetry near the surface region of diamond.
Abstract A method to realize optical nonreciprocity in rotating nano‐diamond with nitrogen‐vacancy (NV) centers is theoretically proposed here. Because of the relative motion of the NV center with respect to the propagating fields, the frequencies of the fields are shifted due to the Doppler effect. When the control and probe fields are incident to the NV center from the same direction, the two‐photon resonance still holds as the Doppler shifts of the two fields are the same. Thus, due to the electromagnetically‐induced transparency, the probe light can pass through the NV center nearly without absorption. However, when the two fields propagate in opposite directions, the probe light cannot effectively pass through the NV center as a result of the breakdown of two‐photon resonance.
Laser-induced fluorescence quenching in nitrogen-vacancy (NV) centers in diamond is studied simultaneously with in situ measurements of the heating-induced shift of the electron spin resonance of NV centers in the presence of a microwave field. These experiments reveal a strong correlation between fluorescence suppression in NV centers and the rise of the local temperature inside the diamond crystal. This finding sheds light on quantum pathways behind stimulated fluorescence quenching in NV centers of diamond and may imply significant limitations on the applications of this effect as a method of superresolving imaging in biological systems.