Fig. 1. (a) Low-temperature PL spectrum of the divacancies in 4H-SiC. Low-temperature PLE resonant scan for divacancy (b) PL1, (c) PL2, (d) PL4, (e) PL5, and (f) PL6. The solid and hollow symbols are the experimental results under repump and pure PLE excitation, respectively. The PLE spectra are fit using Lorentz functions.

Fig. 2. PLE resonant counts (solid symbols) and the corresponding PL enhancement (hollow symbols) as a function of the repump laser wavelength for divacancy (a) PL1, (b) PL2, and (c) PL4, respectively. (d) and (e) PLE resonant counts of PL1 as a function of the repump and pump laser power, respectively. (f) PLE resonant counts of PL1 trace at the 0.1 s time bin using three different repump laser wavelengths.

Fig. 3. (a) PL1 ODMR signals under PLE excitation with different repump laser wavelengths (5 μW) at the zero magnetic field. (b), (c), and (d) The ODMR contrast and FWHM as a function of repump laser wavelength, laser power (670 nm), and resonant pump laser power, respectively. All the black squares in (b)–(d) are the data with the pure resonant pump laser.

Fig. 4. (a) and (b) Measurements of the Ramsey and spin echo of the PL2 under resonant laser (with optimal 670 nm repump laser) and off-resonant (920 nm) laser at a magnetic field of 46 G, respectively. The lines are the fits to the data. (c) Comparison of the dephasing time T2* and coherence time T2 under the resonant laser (solid symbols) and off-resonant laser (hollow symbols) for PL1 (at a magnetic field of 46 G), PL2 (at a magnetic field of 46 G), and PL4 (at zero magnetic field), respectively.