Impact of thermal drifts in LED spectrally sliced WDM systems

Abstract

In LED spectrally sliced wavelength division multiplexed (WDM) systems the optical crosstalk caused by spectral overlapping of adjacent wavelength channels is known to depend on the source spectrum. However, the LED output is temperature dependent and therefore the crosstalk performance of such a system may be expected to vary with operating temperature drifts of the optical source. These effects are theoretically explored to estimate the subsequent performance degradation due to optical crosstalk. Analytical expressions developed indicate that the optical crosstalk noise-to-signal ratio for all spectrally sliced wavelength channels has very little dependence on the LED operating temperature. However, the optical power coupled into a spectrally sliced channel is strongly dependent on the source operating temperature which can cause a depletion of optical power levels within channels placed at the extremes of the source emission spectrum. Hence, the LED source may be employed without any temperature control when precautions are taken in the case of channels located at the tail-ends of the source emission spectrum.