A Theoretical Model of All-optical Switching Induced by a Soliton Pulse in Nano-waveguide Ring Resonator

We propose a theoretical model of 1 x 2 all-optical switching in a silicon nano-waveguide ring resonator induced by a soliton pulse. All-optical switches made by silicon fiber or silicon waveguide have attracted much attention, because the low-absorption wavelength windows of silicon material just match optical fiber communication. However, to achieve all-optical switching in silicon is challenging owing to its relatively weak nonlinear optical properties and require high switching power, which is much higher than the signal power. Such high power is inappropriate for effective on-chip integration. To overcome this limitation, we have used a highly confined nano-waveguide ring resonator structure with soliton pulse input to enhance the nonlinearity and this leads to enhance the effect of refractive index change on the transmission response. The refractive index is changed by controlling the free-carrier concentration through two-photon absorption (TPA) effect. The result indicates that a refractive index change as small as 6.4 x 10(-3) can reduce the switching power to 2.38 x 10(-6) W. The nano-waveguide ring resonator all-optical switching described here is achieved by using the concept of strong light confinement, and the switching power is approximately three orders of magnitude lower than the available silicon optical switches. Such controllable switch is desired for achieving high performance in nanometer-size planar structures.