Zero-phonon line characteristics of SiV center emission in microcrystalline diamond probed with intensive optical excitation

Zero-phonon line (ZPL) position, broadening and intensity of the SiV center emission was monitored in microcrystalline diamond film by using intensive laser excitation of 2.54 eV photon energy. Excitation intensity was varied from 150 kW/cm2 to 700 kW/cm2 to explore changes in the emission region of the zero-phonon line. Two types of characteristic behavior were found in diamond microcrystals. Both the ZPL position and half width of the SiV center emission remain nearly the same in the one type of microcrystalline samples, whilst considerable broadening and red shift of the ZPL of SiV center with the increasing intensity was observed in the other type of microcrystalline samples. GR1 defect center emission under intensive laser excitation is discussed as a possible origin of the observed changes.