[21a-A101-1~11] 3.10 Photonic structures and phenomena (formerly 3.11)

▲ [21a-A101-8] Investigation of diamond-based air-suspended bull’s eye optical cavity

〇(M2)Jieyu Zhou^1,2, Sangmin Ji^1,2, Satoshi Iwamoto^1,2 (1.RCAST, 2.IIS)

Keywords:bull's eye optical cavity, air-suspended, collection efficiency

Color centers in diamonds are a suitable candidate for quantum network nodes. Single-photon emitters based on color centers play an essential role to establish entanglement between quantum nodes at a distance. The efficiency of the single-photon emitters is the primary issue for realizing scalable quantum networks. Photonic crystal cavities have been mainly employed for realizing efficient generation of single photons together with efficient collection of them. Another promising structure is a bull’s eye cavity, which can be designed easily and has less polarization dependence. The improved collection efficiency of single photons from a NV center by introducing a bull’s eye structure in diamond on glass has been demonstrated. In this study, we examine an air-suspended bull’s eye cavity and investigate the influence of the air-gap distance between the cavity layer and the substrate on the single photon emitter’s performance.
The bull’s eye cavity consists of the center disk (diameter 473 nm) surrounding by 8 periods circular gratings. The period of the grating is 197 nm and the widths of air and diamond region in one period of the gratings are the same. To make the structure air-suspended, two channels (width =50 nm) crossing at the center are introduced. Using 3D-FDTD, we calculate the collection efficiency, describing the percentage of photons coupled to an optics with a certain NA over the total amount of extracted photons. The oscillatory behavior is caused by the interference between the light directly go upward and the light reflected by the substrate. Details will be reported in the presentation.