Interactions of Atomistic Nitrogen Optical Centers during Bulk Femtosecond Laser Micromarking of Natural Diamond

Micromarks were formed in bulk natural IaAB-type diamond laser-inscribed by 515 nm 0.3 ps femtosecond laser pulses focused by a 0.25 NA micro-objective at variable pulse energies in sub-picosecond visible-range laser regimes. These micromarks were characterized at room temperature (25 degrees C) by stationary 3D confocal photoluminescence (PL) microspectroscopy at 405 nm and 532 nm excitation wavelengths. The acquired PL spectra exhibit the increasing pulse-energy-dependent yield in the range of 550-750 nm (NV0, NV- centers) at the expense of the simultaneous reciprocal reduction in the blue-green (490-570 nm, H-band centers) PL yield. The detailed analysis indicates low-energy intensity rise for H-band centers as an intermediate product of vacancy-mediated dissociation of B1 and B2 centers, with H4 centers converting to H3 and NV centers at higher pulse energies, while the laser exposure effect demonstrates the same trend. These results will help solve the problem of direct laser writing technology, which is associated with the writing of micromarks in bulk natural diamond, and promising three-dimensional micro-electrooptical and photonic devices in physics and electronics.