Dispersion Enhancement and Linearization in a Dynamic DWDM Channel Blocker

A dynamic dense-wavelength-division-multiplexing (DWDM) channel blocker and equalizer is developed based on liquid crystal (LC) and dispersion control technology. A multipixel LC array is adopted to regulate the power level of each DWDM channel, while a reflective grating diffracts the input signals spatially to corresponding LC pixels. A dispersion control unit is proposed and employed to enhance the dispersion and compensate the intrinsic nonlinear dispersion of the grating. Therefore, all LC pixels could handle corresponding lights centered at the International Telecommunications Union Grids. A 40-channel, 100-GHz channel-spacing dynamic wavelength blocker/equalizer is thus demonstrated with -5 dB insertion loss and over 40 dB extinction ratio. The maximum center frequency shift of all 40 channels is ~ ??2 GHz, which means our dispersion control technology works very well for grating-based DWDM devices.