Flat band slow light in asymmetric photonic crystal waveguide based on microfluidic infiltration

In this paper, an asymmetric photonic crystal waveguide is proposed for flat band slow light transmission. Two structural parameters of one cladding layer of the waveguide are carefully adjusted. They are the refractive index of the liquid infiltrated in the cladding on one side and the radius of the air holes in the infiltrated cladding. In such an asymmetric waveguide, we can achieve a very flat band corresponding to high group index such as 29.4 and low dispersion (10⁴ps²/km) for δω/ω= 1.46%. It is found that the value of n_gδω/ω of the proposed waveguide can reach 0.429 and this waveguide can also yield a significant increase in the group index-bandwidth product n_gω/ ω and improve the bandwidth.