Polarization-independent waveguides in air holes photonic crystals and its slow light

• A polarization-independent single-mode waveguide is proposed.
• Polarization-independent transmission was demonstrated by using Finite-Difference Time-Domain (FDTD) in a long straight and 60° bend waveguide.
• The guided modes are shown to exhibit a wide-bandwidth slow light and an extremely low group velocity dispersion in most frequency range.

A line-defect waveguide in a triangular lattice photonic crystal (PC) made of air holes in dielectric is demonstrated to support transverse magnetic (TM) as well as transverse electric (TE) guided modes simultaneously. A group of suitable geometric parameters were found to make the guided bands overlapped by means of Genetic Algorithm. The optimized waveguide realizes a polarization-independent single-mode transmission and wide operating bandwidth which reaches 0.012Δωa/(2πc)Δωa/(2πc). Moreover, the guided modes are shown to exhibit a wide-bandwidth slow light and an extremely low group velocity dispersion in most frequency range.