Crosstalk evaluations of optical add/drop multiplexer in WDM-ring networks

The influences of power and wavelength (frequency) uncertainties as well as crosstalk were investigated by means of a recirculating loop experiment with 10 Gbit/s NRZ formatted signals. Two general kinds of optical add/drop multiplexer (OADM) were evaluated experimentally by introducing into the loop an arrayed-waveguide grating (de)multiplexer (AWGM) or fibre Bragg grating OADM. The measurement of cascading effects due to OADM based on the arrayed-waveguide grating show an acceptable frequency uncertainty of +or-3.5 GHz for both transmitter and AWGM, respectively. The measurement of the relation between OADM crosstalk and gain variations show a tolerable gain detuning of approximately +or-3 dB and at least the measurement of relation between crosstalk and detuning of an OADM based on the fibre Bragg grating give a range of stable operation within +or-20 GHz or 17 degrees C to 37 degrees C, respectively.