Utilizing photonic band gap in triangular silicon carbide structures for efficient quantum nanophotonic hardware

Abstract

Silicon carbide is among the leading quantum information material platforms due to the long spin coherence and single-photon emitting properties of its color center defects. Applications of silicon carbide in quantum networking, computing, and sensing rely on the efficient collection of color center emission into a single optical mode. Recent hardware development in this platform has focused on angle-etching processes that preserve emitter properties and produce triangularly shaped devices. However, little is known about the light propagation in this geometry. We explore the formation of photonic band gap in structures with a triangular cross-section, which can be used as a guiding principle in developing efficient quantum nanophotonic hardware in silicon carbide. Furthermore, we propose applications in three areas: the TE-pass filter, the TM-pass filter, and the highly reflective photonic crystal mirror, which can be utilized for efficient collection and propagating mode selection of light emission.

Triangular quantum photonic devices with integrated detectors in silicon carbide

“…Single mode propagation [41,42] and positioning of emitter at the centroid of the triangular cross-section [10,22] ensures that most of the color center emission is coupled into the waveguide. It was shown that 45 • etch angle has predicted the best results for the complete band gap [23]. But in this study, an etch angle of 60 • was chosen because the optimal emitter position is closer to the top surface, offering realistic implantation depths (70 nm) and efficient absorption in the SNSPDs.…”

“…Photonic band structures in triangular geometry have not been studied in detail. In this light, our recent work provides an insightful explanation of the dispersion relations in SiC triangular geometry [23]. From the band structures obtained from PWE method, we use FDTD method to analyze the performance of the triangular-cross section 1D PCM and the dependence of the coupling efficiency to the waveguide mode on the emitter position with respect to the PCM.…”

“…Figure 2(c) delineates the changes in the TE/TM gap (c/a) and the corresponding gap size (gap-midgap ratio) with r/a for w values of 1.2a, 1.35a and 1.5a. Midgap frequency increases with r/a for both TE and TM band gaps as volumetric fill factor (VFF) and effective refractive index (n eff ) have an inverse relationship with r/a [23]. Gap size initially increases with r/a as fewer propagating modes are supported, but declines after the maximum value is reached.…”

“…(Inset) The cross-section view of the structure, showing the color center (blue) optimally positioned at the centroid of the triangular waveguide profile. photonic modes have been recently studied in terms of waveguide propagation [10,22], photonic crystal (PC) band gap formation [23], PC cavity resonances [22], and grating coupler performance [24].…”

“…PCM has a periodic variation of refractive index, which results in the formation of photonic band gaps. Understanding the formation of these band gaps is necessary for applications in selective reflection of the ZPL and PSB emissions with the goal of enhancing light collection efficiency [23]. The other side of the waveguide deals with the efficient detection through hybrid integration with NbTiN SNSPDs.…”