80 to 10 Gbit/s demultiplexing using fiber cross-phase modulation and optical filtering

We demonstrate a new demultiplexer based on XPM in a fiber that utilizes the derivative feature of XPM induced spectral broadening. The basic idea is that the leading edge of the control pulse generates a red shift of the spectrum of the XPM modulated input signal, and the trailing edge generates a blue shift. We have previously reported wavelength conversion using this technique where the incoming data phase modulate continuous wave (CW) light with subsequent conversion to amplitude modulation. Here, only one of the OTDM data channels in the high bit-rate data is spectrally broadened and that channel can then be extracted with a narrow band optical band-pass filter at either side of the original spectrum. Thus, only one edge of the control pulse governs the width of the demultiplexing switch window, if dispersive walk-off is neglected. Therefore a control pulse broader than the actual bit slot can be used for demultiplexing. Another important feature of this demultiplexer compared to the NOLM is that it is not an interferometer, which makes the device completely insensitive to environmental disturbances even though a long length of fiber is used