Enhanced emission collection of V B - in hexagonal boron nitride by solid immersion lens and plasmon

Hexagonal boron nitride (hBN) has brought widespread attention as a host material of various quantum emitters due to its two-dimensional nature and wide bandgap. Among the versatile quantum emitters in hBN, the negatively charged boron vacancy ( V (B) -) stands out for its high contrast of optically detected magnetic resonance signal and the ability of spin control. Here, we report a method to implement 8.6-fold photoluminescence enhancement of V- B - by using a solid immersion lens (SIL). We further combined an Au waveguide, Ag nanoparticles, and SIL to achieve an 18.6-fold photoluminescence overall enhancement of V (B) -. Our work provides a portable method to enhance the collection and emission efficiency of V B -, which is helpful for its practical applications in quantum technologies such as quantum sensing and quantum information.