Optical SCM data extraction using a fiber-loop mirror for WDM network systems

We demonstrate the use of a polarization-independent dual-port filter to extract subcarrier multiplexed (SCM) data from a baseband/SCM channel while the baseband is passed through with minimal distortion. This architecture solves the fiber dispersion-induced fading problem for SCM channels and eliminates the complexity of single-sideband modulation techniques by suppressing the optical carrier at the tap port prior to photodetection. Bit-error-rate (BER) measurements were performed on the baseband channel showing that the SCM removal prior to photodetection reduces crosstalk with the subcarrier channel. The BER on the SCM data shows no effect of dispersion-induced fading. The periodic optical frequency characteristic of the filter can be matched to the ITU grid, making this tap applicable to multichannel WDM networks.