Broad working bandwidth and “endlessly” single-mode guidance within hybrid silicon photonics

Abstract

The successes of nonlinear photonics and hybrid silicon photonics with a growing variety of functional materials entail ever-enlarging bandwidths. It is best exemplified by parametric comb frequency generation. Such operation challenges the dielectric channel waveguide as the basis for guidance, because of the adverse advent of higher order modes at short wavelengths. Surprisingly, the popular mechanism of endlessly single-mode guidance [Opt. Lett.22, 961 (1997).] operating in photonic crystal fibers has not been transposed within silicon photonics yet. We outline here the strategy and potential of this approach within planar and hybrid silicon photonics, whereby in-plane and vertical confinement are shown to be amenable to near-single-mode behavior in the typical silicon band, i.e., λ=1.1 μm to ∼5 μm.

Mid-infrared waveguides for broadband single-moded guidance

“…We recently demonstrated a waveguide on a silicon-on-insulator (SOI) platform that allowed for single-moded guidance over an octave of frequency [2]. The design of this waveguide is illustrated in Figure 1 and was originally inspired by the well-known endlessly single-mode (ESM) guidance found in photonic crystal fibres [3]. Instead of the step-index cladding found in conventional waveguide designs, the cladding of the ESM waveguide is a twodimensional grating.…”