Loss-less tunable per-channel dispersion compensator

An all-pass optical filter comprising:

• an input port for receiving an input optical pulse having a packet of waves at corresponding frequencies, each frequency having an amplitude and a channel bandwidth, the packet of waves having a plurality of frequencies and spacing between the plurality of frequencies conforming to an International Telecommunications Union grid (ITU grid);
• an output port;
• and
• at least one semiconductor optical amplifier disposed between the input port and the output port for providing a Fabry-Perot cavity as defined by a pair of reflectors, the Fabry-Perot cavity tuned to have a phase transfer function for providing a periodic frequency response exhibiting a spectral periodicity defined as a free spectral range (FSR), the FSR matched to a multiple of the ITU grid in the plurality of freqencies and spacing, the multiple including one, wherein the semiconductor optical amplifier is tuned to apply a desired frequency-dependent time delay to each frequency of each wave in the packet of waves contained in the optical pulse entering the input port such that the group delay dispersion of pulses transmitted through the output port approximates a constant value, over the channel bandwidth, so that net transmission system group delay dispersion of the optical pulse defined by the first derivative of the transmission system group delay to reduce to about zero, and wherein the semiconductor optical amplifier has a uniform amplitude transfer function to substantially preserve the amplitude of each frequency of the optical pulse transmitted to the output port.