High-speed tunable filter using ferroelectric smectic C* liquid crystal materials

As the Er-doped fiber amplifier (EDFA) has begun to define the operating window of many optical wavelength-division-multiplexed (WDM) networks, there is a need for electronically-tuned optical filter capable of spanning the entire gain curve of the EDFA. Although various types of tunable filters are now commercially available or currently under extensive research, they are either limited by tuning speed (such as piezo driven fiber Fabry-Perot (FP) and nematic liquid crystal filters), or cost (piezo driven fiber FP and acoustically-tuned filters). A miniature, inexpensive device that can rapidly tune sources and/or receivers is imperative for the future WDM packet-switching networks. Here, we described such a filter that will tune through the whole spectrum of the EDFA (~30 nm at 1.55 μm) with the tuning speed of 50 K-1 MHz