Five-Line Photonic Crystal Waveguide for Optical Buffering and Data Interconnection of Picosecond Pulse

A five-line (5L) photonic crystal waveguide (PCW) capable of realizing compact, optical buffering and low-distortion data interconnection of picosecond pulse is presented and studied through plane-wave expansion and finite-difference time-domain methods. By appropriately modifying the radii of defects in the 5L PCW, high buffering performance and low-distortion slow light transmission of picosecond pulses are achieved, which are guaranteed by an optimized value of normalized delay bandwidth product (NDBP) of 0.6811 for the proposed PCW. The largest buffering storage capacity and bandwidth obtained are about 219.73 bit and 19.55 nm, respectively. It is found that the distortion of pulse transmission in a PCW is greatly affected by the waveguide length. With these optimized parameters, a relative pulse distortion per unit length of 1.15×10−4 µm−1 is obtained for a 2.19-ps pulse, meaning that for a signal pulse with a dutyfactor of 0.5, the proposed structure can process optical digital pulse signals at the speed of 0.22831 Tb/s. Moreover, the NDBP value of 0.6811 obtained is much higher than that of all other structures based on waveguides reported in the literature previously so that high performance of the proposed PCW can be achieved. The waveguide proposed is suitable for data interconnections among chips or among processing units within a chip in optical signal processing, and computations where the size of the transmission line or interconnector is highly limited.