A butt-coupled low dispersion slow light photonic crystal waveguide has been proposed in this paper. It is comprised of
two types of photonic crystal waveguides which have opposite dispersion curve. These two types of photonic crystal
waveguides have been solely adjusted the radius of air-holes rather than change its position. Based upon our analysis, the
average group index achieves 35 with Δ λ=6nm and this scope can be enlarged by fine adjustment. Finite-different timedomain
method has been adopted to execute the simulation and the result demonstrates that the pulse has been modified
when it propagates in this butt-coupled photonic crystal waveguide.
We investigate the nonlinear characteristics of the Mach-Zehnder (MZ) intensity modulator using based on Bessel
series expansion. The method we used provides the easy characterization of the harmonic components of an MZ
intensity modulator. Theoretical analysis results are agreeable with those obtained in the experiment. Compared to the
traditional methods, this method can analyse the operating characteristics of the MZ intensity modulator without
executing a complicated experiment. It can not only be used to characterize harmonic component of MZ intensity
modulator with high accuracy and fast calculation, but also can be extended to analyze the nonlinear distortion of the
analogue signal modulation.