Dynamic modulation of wideband slow light with continuous group index in polymer-filled photonic crystal waveguide.

Abstract

The dynamic modulation of wide bandwidth and low-dispersion slow light with continuous variation of group index ng is realized in a polymer-filled photonic crystal waveguide (PF-PCW) with optimal structure. By adjusting the unified radius of air holes under a different refractive index of polymer in the first two rows of holes adjacent to the defect, the structure optimization of PF-PCW is first studied, then the fixed optimal structure is obtained. In the optimal photonic crystal waveguide with hole radius r0=0.328a, a fixed refractive index n1=1.74 of polymer in the first-row holes, and by adjusting refractive index n2, the flattened wideband slow light with large normalized delay bandwidth product of group index from 17.15 to 55.65 has been demonstrated. Then, by filling polymer with electro-optic effect into the second-row holes, the dynamic modulation of the optimized slow light in PF-PCW is investigated. The simulation shows that the center operating frequency slightly shifts linearly to a higher one, and the average group index increases exponentially from 33.943 to 75.546 with a normalized delay bandwidth product larger than 0.3089 as the applied voltage increases. The modulation sensitivity of the average group index is about 0.3467/V when applied voltages vary from 0V to 120V. These results open the possibility for the dynamic control of slow light according to the practical requirements of flexibility and tunability.