Laser writing of spin defects in nanophotonic cavities

• Published in: Nature materials 2023-06, Vol.22 (6), p.696-702
• Main Authors: Day, Aaron M., Dietz, Jonathan R., Sutula, Madison, Yeh, Matthew, Hu, Evelyn L.
• Format: Article
• Language: English
• Subjects: 639/301/1019/1022; 639/624/400/1021; 639/925/927/481; Amorphization; Biomaterials; Chemistry and Materials Science; Condensed Matter Physics; Coupling; Crystal defects; Defect annealing; Defects; Direct laser writing; Emitters; Energy gap; Excitation; Holes; Irradiation; Lasers; Letter; Materials Science; Nanosecond pulses; Nanotechnology; Optical and Electronic Materials; Photoluminescence; Photonic crystals; Pulsed lasers; Real time; Silicon; Silicon carbide; Spin resonance; Substrates
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/s41563-023-01544-x

High-yield engineering and characterization of cavity–emitter coupling is an outstanding challenge in developing scalable quantum network nodes. Ex situ defect formation systems prevent real-time analysis, and previous in situ methods are limited to bulk substrates or require further processing to improve the emitter properties 1 – 6 . Here we demonstrate the direct laser writing of cavity-integrated spin defects using a nanosecond pulsed above-bandgap laser. Photonic crystal cavities in 4H-silicon carbide serve as a nanoscope monitoring silicon-monovacancy defect formation within the approximately 200 nm 3 cavity-mode volume. We observe spin resonance, cavity-integrated photoluminescence and excited-state lifetimes consistent with conventional defect formation methods, without the need for post-irradiation thermal annealing. We further find an exponential reduction in excited-state lifetime at fluences approaching the cavity amorphization threshold and show the single-shot annealing of intrinsic background defects at silicon-monovacancy formation sites. This real-time in situ method of localized defect formation, paired with cavity-integrated defect spins, is necessary towards engineering cavity–emitter coupling for quantum networking. Using direct laser writing with a nanosecond pulsed laser operating at above-bandgap photon energies, we demonstrate the selective formation of spin defects in photonic crystal cavities in 4H-silicon carbide and their in situ characterization.