In this paper, we designed and analyzed an efficient taper structure to couple light into and out of photonic crystal waveguides (PhCWs) fabricated by Si-ion implantation and electron beam lithography. The coupling structure employs the gentle refractive-index distribution produced in the SiO2layer by Si-ion implantation. A taper structure is designed for effective coupling of transverse electric (TE) polarized light (λ = 1.55 μm) into a submicron size PhCW consisting of triangular lattice of air holes (lattice constant,a= 0.666 μm, radius of air holes,r= 0.232 μm, waveguide width, W1 ~ 0.7 μm). The influence of the taper length on the transmission characteristics is investigated. Efficiency in excess of 95% is demonstrated using the finite-difference time-domain and beam propagation methods. This is important for their practical applications in photonic integrated circuits.
Terahertz Waveguides: Broadband Single‐Mode Hybrid Photonic Crystal Waveguides for Terahertz Integration on a Chip (Adv. Mater. Technol. 7/2020)