Design and implementation of a tunable composite photonic crystal cavity on an optical nanofiber

We report a novel approach to the design and implementation of a tunable cavity on an optical nanofiber (ONF). The key point is to create a composite photonic crystal cavity (CPCC), by combining an ONF and a diverged period defect mode grating. Using numerical simulations we design the CPCC with low scattering loss while tuning the cavity resonance wavelength of ±10 nm around the designed wavelength. We experimentally demonstrate the tunability of the CPCC, showing good agreement with the simulation results. Our results lay the foundation for a versatile platform for ONF cavity-quantum-electrodynamics with narrow bandwidth quantum emitters.