Yijing Chen, Vivek Krishnamurthy, Yicheng Lai, and Seng-Tiong Ho, "Realization of ultrafast all-optical switching with switching gain in a single semiconductor waveguide," Opt. Lett. 39, 3567-3570 (2014)
In this letter, we report for the first time that all-optical switching gain can be achieved with a dual-wavelength control vs pump beam scheme in a single semiconductor waveguide structure. That means a weak optical beam can switch a strong optical beam. Moreover, a high switching speed of 10-100Gb/s can be achieved. The all-optical switching is simulated numerically via a multi-level multi-electron (MLME) FDTD program capable of modeling complex semiconductor band properties. It is shown that a weak control/input-signal beam at a longer wavelength is able to switch the transmission of a strong pump/output-signal beam at a shorter wavelength. A 50Gbps and 0.5pJ per bit switching operation with switching gain of around 10 is shown for a 40m-long waveguide with pump beam power around 20mW based on bulk InGaAsP material and a 300nm x 300nm waveguide (the control beam power is 1/10 of that for the pump).