Single-mode optical waveguides on native high-refractive-index substrates

Abstract

High-refractive-index semiconductor optical waveguides form the basis for modern photonic integrated circuits (PICs). However, conventional methods for achieving optical confinement require a thick lower-refractive-index support layer that impedes large-scale co-integration with electronics and limits the materials on which PICs can be fabricated. To address this challenge, we present a general architecture for single-mode waveguides that confine light in a high-refractive-index material on a native substrate. The waveguide consists of a high-aspect-ratio fin of the guiding material surrounded by lower-refractive-index dielectrics and is compatible with standard top-down fabrication techniques. This letter describes a physically intuitive, semi-analytical, effective index model for designing fin waveguides, which is confirmed with fully vectorial numerical simulations. Design examples are presented for diamond and silicon at visible and telecommunications wavelengths, respectively, along with calculations of propagation loss due to bending, scattering, and substrate leakage. Potential methods of fabrication are also discussed. The proposed waveguide geometry allows PICs to be fabricated alongside silicon CMOS electronics on the same wafer, removes the need for heteroepitaxy in III-V PICs, and will enable wafer-scale photonic integration on emerging material platforms such as diamond and SiC.

Spin Readout Techniques of the Nitrogen-Vacancy Center in Diamond

“…Furthermore, technical issues associated with submicron diamond membranes (e.g., enhanced strain, nonparallel surfaces and laborious fabrication requirements) have impeded the widespread adoption of these approaches. New designs and fabrication approaches that allow waveguides and cavities to be created directly from bulk diamond crystals [ 70 , 71 ] potentially offer a way forward, although the control of surface noise that causes deteriorated optical linewidths in nanophotonic structures remains a formidable challenge. One approach to avoiding these sources of noise is to use NVs embedded within diamond membranes of micron-scale thickness, which can be aligned within high-finesse fiber-based cavities, albeit with larger mode volumes ( Figure 2 d) [ 59 , 72 , 73 ].…”

Fabrication of (111)-faced single-crystal diamond plates by laser nucleated cleaving

“…Advances in homoepitaxial chemical vapor deposition (CVD) of high-purity single-crystal diamond (SCD) have made the exceptional material properties of SCD available for a variety of new and exciting applications [1][2][3][4]. In particular, the wide bandgap, high carrier mobility, large thermal conductivity, corrosion resistance, and biocompatibility of SCD have enabled new devices for high-power electronics [5], ultraviolet light sources [6] and detectors [7], nonlinear optics [8][9][10], quantum information processing [11], biomedical applications [12,13], magnetometry [14], and integrated photonics [15][16][17][18][19].…”

Tailoring diamond’s optical properties via direct femtosecond laser nanostructuring

“…The development of simple and reliable techniques for the fabrication of diamond components including diffraction gratings 11 , moth-eye antireflection coatings 12 , field emitters 13 , 14 , waveguides, resonators and couplers for quantum processing 15 is a very active area of research. Perhaps, the most important bottleneck for diamond surface nano-processing is that the established techniques used for patterning other semiconductors such as silicon wafers are either ineffective or require complicated fabrication steps.…”