Research On Slow Light Characteristics Based On Photonic Crystal Waveguides

The existence of electronic bottleneck restricts the development of light cache technology. The realization of slow light has solved light cache technology problem. The best way to obtain slow light is photonic crystal waveguide structure. While line-defect waveguides or coupled cavity waveguides obtain slow light, large group velocity dispersion is followed, which makes signal deformed and distortion and limits slow light transmission capacity.In order to obtain slow light properties with wide bandwidth and low dispersion, on the one hand, we need to investigate photonic crystal structure with wider band gap, on the other hand need to design waveguide structures to obtain guide mode with the larger normalized delay bandwidth product.In view of band gap problem, investigation finds that circular holes triangular lattice photonic crystal and hexagon holes triangular lattice photonic crystal's rang of band gap is 0.12~0.15, and circular holes square lattice photonic crystal' band gap is 0.12. These band gaps are wide enough to reduce light energy loss, suitable for designing of waveguides.On purpose of obtain guide mode with bigger normalized delay bandwidth product, in this text we propose two different waveguide structures. Circular holes near line-defect waveguide are replaced by rectangular air holes and eye-shaped holes respectively, when rectangular holes and eye-shaped holes changed, analyzing the influence to slow light properties. Results show that within the linear region that average group index varies at a variation of ±10% range, when circular holes replaced by eye shaped holes, guide mode can obtain biggest normalized delay-bandwidth product about 0.366, bandwidth about 22.5nm, group velocity dispersion about 2.54 ps2/mm; when circular holes replaced by rectangular holes, guide mode can obtain biggest normalized delay-bandwidth product about 0.402, bandwidth about 65.3nm, group velocity dispersion about 8.0 ps2/mm. Comparison of slow light properties show that waveguide introducing rectangular holes is better than waveguide with eye-shaped hole. It provides certain theoretical basis for designing of light cache devices.