Towards Site-Selective Fabrication of Near-Infrared Emitters in hBN

Abstract: Spatial control of near-infrared (NIR) emission from hexagonal boron nitride (hBN) would facilitate coupling atomic-scale light sources to photonic structures, yet oxygen-related NIR emitters are generally formed at stochastic locations. Here, we combine single-shot femtosecond laser writing with annealing in an oxygen-rich environment to bias NIR activation toward predefined coordinates in exfoliated hBN. Spectra acquired with 532, 635, and 785 nm excitations show narrow and multipeak emission extending to a wavelength of 1 um. Among the spectra collected at written sites, over 83% under 785 nm excitation and 71% under 635 nm excitation contain at least one resolved peak above 810 nm. The emission intensity increases monotonically with writing-pulse energy, suggesting tunability and indicating that the optimum for the single-emitter regime may require lower energies. Band-pass-resolved measurements show zero-delay correlation dips with g2(0) values indicative of single-photon emission but also reveal contributions from the spectral background. Spectrally resolved time series under 785 nm excitation show persistent bands over the recorded intervals as well as intermittent emission above 900 nm. This approach demonstrates NIR-emitter activation at predefined sites while identifying residual off-site activation and spectral multiplicity as the principal targets for further optimization.