Narrowband tunable optical filter for channel selection in densely packed WDM systems

One of the more vexing problems inhibiting implementation of densely packed wavelength division multiplexed (WDM) lightwave systems is channel selection or demultiplexing. Coherent detection in which a tunable local oscillator provides the channel selection has been proposed1 and demonstrated.2 However, this method of channel selection shares all the difficulties and additional complexities of coherent detection, i.e., the need for tunable narrow-linewidth lasers and more sophisticated receiver electronics than In direct detection receivers and the inability to operate at low bit rates. Here we demonstrate an alternate method based on stimulated Brillouin amplification tor channel selection, which does not have severe restrictions on laser linewidths and bit rates and uses present direct-detection receivers.