Engineering a mechanically stable hybrid photonic crystal cavity coupled to color defects in diamond

Abstract

Wavelength scale photonic, high-quality factor (Q-factor), cavities are crucial for enhancing light- matter interaction. Such on-chip hybrid devices could potentially provide a route towards scalable quantum technologies with color defects in diamond. A variety of designs for photonic crystal cavities have been proposed; however, the challenging and multi-step fabrication processes required for such designs limit the experimentally observed Q-factors in addition to significant radiation loss. One possible way to minimize the radiation loss in a one-dimensional (1-D) photonic crystal cavity is by introducing a so-called Gaussian defect region around the cavity. In this work, we propose a versatile approach to designing a Gaussian defect region by changing the lattice parameter in a 1-D photonic crystal. Further, to circumvent the problem of creating freestanding cavities for achieving high-Q factor in a 1-D photonic crystal cavity, we propose a novel hybrid diamond-titanium dioxide (TiO2) based materials for color defects in diamond, in particular the nitrogen-vacancy (NV−) center. Our proposed mechanically stable and high-Q cavity could be crucial for on-chip integration of different nanophotonic components for chip-scale photonic devices. We show via simulations that Q-factor > 105 can be achieved with the device.