Densely spaced FDM coherent star network with optical signalsconfined to equally spaced frequencies |
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Authors: | Glance BS Stone J Pollock KJ Fitzgerald PJ Burrus CA Jr Kasper BL Stulz LW |
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Affiliation: | AT&T Bell Lab., Holmdel, NJ; |
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Abstract: | The results obtained with a fiber-optical star network using densely spaced frequency-division-multiplexing (FDM) and heterodyne detection techniques are discussed. The system consists of three optical sources transmitting around 1.28 μm, frequency-shift keying (FSK) modulated at 45 Mb/s and spaced by 300 MHz. A 4×4 optical coupler combines the three optical signals. The FDM signals, received from one of the four outputs of the coupler, are demultiplexed by a heterodyne FM receiver. The minimum received optical power needed to obtain a bit error rate (BER) of 10-9 is -61 dBm or 113 photons/bit, which is 4.5 dB from the shot noise limit. Cochannel interference is negligible for the above channel spacing and modulation rate. The results indicate that such a system has a potential throughput of 4500 Gb/s. The results obtained with two frequency stabilization circuits used to confine these three FDM optical signals to a comb of equally spaced frequencies are also presented |
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