A Femtosecond All-Optical Switch Based on Surface Plasmon Polaritons

Surface plasmon polaritons (SPPs) propagate along the interface between metal and dielectric, so that SPPs can propagate along the designed interface, spread to the specified region and convert back to light wave. Through this method, modulated light can be guided to setting area and the propagation direction can be changed. In this paper, a kind of all-optical switch composed of metallic isosceles triangle is introduced. The principle of the all-optical switch is this. Firstly, the modulated light is converted into SPPs in the metal triangle at the bottom corner. Then, SPPs propagate along designed interface between metal and dielectric. Finally, SPPs become scattered light in the vertex of triangle where the signal light also become scattered light. Two scattering light interfere cancellation to achieve the goal that the modulation with very low power light can control the signal light. The most remarkable advantage of the all-optical switch is that the incident angle of modulated light does not require strictly. As long as the light intensity and phase of light is proper, the aim of extinction can be achieve. The reaction speed of the all-optical switch is nearly the speed of light. Response time is 0.9 femtosecond. Extinction ratio is about 34.93558dB. The entire structure size is only 1.8 mu m x 1 mu m (x x z). The all-optical switch has the characteristics of low threshold power, small size and easily integrated. In the case of relatively high extinction, the switch can control signal of any channel. It is able to be applied to high-speed, large capacity, channel spacing of 0.8nm DWDM optical network