Abstract: In this paper, the influences of nonlinear gain compression (NGC) on switching characteristics of a terahertz optical asymmetric demultiplexer (TOAD) are investigated thoroughly by taking into account the gain saturation and NGC effects of semiconductor optical amplifier (SOA). And a concept of effective switching window width is presented for the first time. It is shown that the switching window shape is influenced dramatically by the NGC. The bigger NGC is, the more sensitive is the TOAD output to the position of the SOA. If the NGC is small, however, the control pulse energies will have great effects on the effective switching window width. Only when the control pulse is narrow, will the effective switching window width be influenced by the NGC. The effective switching window width will be small if the NGC and the distance between the SOA and the midpoint of the loop are small.

Key words: WTBZterahertz optical asymmetric demultiplexer, nonlinear gain compression, switching characteristics, effective switching window width