We propose a scheme for reduction of cross-talk arising form stop-band rejection limitation of optical band-pas filters in a wavelength-division multiplexing receiver. Experiment confirms high selectivity of the receiver and reveals feasibility of optical packet ultra dense WDM systems spaced by several GHz.
The receiver consists of optical switches at input and output ports of a fiber loop, which contains fiber delay line, tunable optical band-pass filters, an erbium-doped fiber amplifier, and an optical switch.
Target packet is selected from input optical packet WDM signals by time and wavelength windows realized by the optical switches at the input and output ports of the fiber loop, and the tunable filters in the loss compensated fiber loop, respectively.
The selectivity is measured by using pulsed lightwave sweep frequency, which contains 7 frequencies in 500MHz step. The results show 11dB suppression for signals 2 GH apart from the target channel after 10 circulation, and 12dB suppression for signals 1.5 GHz apart from the target channel after 18 circulation.
Details of the receiver configuration, pulsed lightwave sweep frequency generator and experimental results are discussed.