Performance influence of carrier absorption to the Mach-Zehnder-interference based silicon optical switches.

The free carrier absorption effect in silicon modulation is a detrimental behavior that can influence the crosstalk of interference-based optical switches. Based on the experimental analysis of a 2x2 p-i-n silicon switch, we give a conservative estimate of the crosstalk ability of Mach-Zehnder optical switches. Experimental result shows that, while using a 1475 microm-long phase shifter, the loss penalty almost reaches 1.45 dB/pi, which deteriorates the most ideal crosstalk to just 30 dB. The possible solutions to overcome this limitation are also discussed at the cost of the other device performance.