ArXiv · 2026
Near-infrared (NIR) emitters in hexagonal boron nitride (hBN) have recently emerged as bright and spectrally stable light sources, but they have so far been found at locations set by the local defect environment rather than by design. Here we show that NIR emitters can be activated at predefined sites by combining single-shot femtosecond laser writing with annealing in an oxygen-rich environment. To our knowledge, this is the first demonstration of site-selective activation of NIR emitters in hBN. The written matrices are recovered in post-anneal photoluminescence maps, including in collection bands centred at 800 and 900 nm. Site-resolved spectra under 532, 635 and 785 nm excitation show narrow lines extending to 1 um; 83% of the spectra acquired at written sites under 785 nm excitation and 71% under 635 nm excitation contain at least one resolved peak above 810 nm. The integrated emission increases with writing-pulse energy over the range studied, and many sites host more than one emitter, which identifies lower writing energies as the route to single-emitter occupancy. Photon-correlation measurements on selected sites show antibunching, with a raw, uncorrected second-order correlation value g(2)(0) of 0.31 in a band centred at 850 nm. Spectral time series reveal bands that persist over the recorded intervals together with intermittent emission beyond 900 nm. Comparison with identically written, argon-annealed samples indicates that the annealing atmosphere controls the spectral range of the activated emitters, while the laser defines where they form.
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