Impact of thermal drifts in LED spectrally sliced WDM systems

In LED spectrally sliced wavelength division multiplexed (WDM) systems the optical crosstalk caused by spectral overlapping of adjacent wavelength cha nnels is known to depend on the source spectrum. However, the LED output is temperature dependent and therefore the crosstalk performance of such a sy stem may be expected to vary with operating temperature drifts of the optic al source. These effects are theoretically explored to estimate the subsequ ent performance degradation due to optical crosstalk. Analytical expression s developed indicate that the optical crosstalk noise-to-signal ratio for a ll spectrally sliced wavelength channels has very little dependence on the LED operating temperature. However, the optical power coupled into a spectr ally sliced channel is strongly dependent on the source operating temperatu re which can cause a depletion of optical power levels within channels plac ed at the extremes of the sourer emission spectrum. Hence, the LED source m ay be employed without any temperature control when precautions are taken i n the case of channels located at the tail-ends of the source emission spec trum. (C) 1999 Elsevier Science B.V. All rights reserved.