Conversion wavelength and power dependence of the time delay and output signal quality for an optical delay
system consisting of dispersion compensation fiber (DCF) and highly nonlinear fibers (HNLFs) is investigated in
this paper. The numerical results show that the time delay generally varies linearly with the conversion wavelength
propagating through DCF and changes slightly with the power launched into HNLFs. But it has abrupt change at
some values of conversion wavelength or input power level. Output signal quality of the overall system varies
significantly with the conversion wavelength and input power level. The reasons behind these results are analyzed.
Finally, the input power level is optimized to achieve linearly varying time delay and desirable output signal
quality for an optical delay system.
Progress in optical network has stimulated interest in optical performance monitoring (OPM). Optical sampling
technique is believed to be a promising candidate to monitor the physical state of the network. The theoretical model of a
monitoring system based on optical sampling in semiconductor optical amplifier (SOA) and software synchronized
algorithm is constructed. Compared with the results obtained by Optsim, the monitoring system model is proved. For
10Gb/s NRZ (RZ) optical signals, the differences on Q values between the results obtained by SOA and the ideal
sampling processes are 0.195dB (0.247dB), 0.988dB (0.594dB), and 1.707dB (0.596dB) for pump energy equal to, ten
times of and fifty times of the optical data signal energy respectively. The sampling device can induce degradations of
the sampling results. It is mainly because of the gain saturation and the nonlinear effects in SOA. The high input power
can make the gain saturated deeply and further influence the probe and conjugate outputs. At the same time, the pump
power should not be too low. The proper pump power will obtain better sampling linearity and better sampling results.