Research On Theory And Applications Of All-Optical Switch Based On Photonic Crystals

All-optical switch technologies have a wide range of applications. The all-optical switch using existing means is not conductive to the integration of future all-optical devices, because of its large volume. What’s more, some extremely strict requirements are needed for a few means. By contrast, all-optical switch based on photonic crystals with third-order nonlinear materials has unparalleled advantages. In this thesis, we investigate photonic crystal all-optical switch and put forward two approaches based on nonlinear photonic crystal. We also design the structure of WDM based on ring resonator and resonant coupling micro-cavity to integrate with all-optical switch. We complete the following three aspects:1) To obtain an optimum structure of all-optical switching, based on90°photonic crystal waveguide bends, an improved photonic crystal all-optical switching structure with kerr nonlinear material rods is introduced. By means of finite difference time domain (FDTD), our numerical analysis shows that, this switching can achieve the following performances:bandwidth (about50nm), high extinction ratio (above40dB), threshold power density (5.2w/μm). At the same time, it can also implement simple logical functions.2) We investigate the properties of a ring resonator and resonant coupling microcavity based on photonic crystals and put forward the structure of WDM, which can be integrated with all-optical switch designed last chapter. By changing the central radius of resonant coupling microcavity, a function of WDM is performed at wavelengths1550nm and1600nm. In addition, increasing the radius of output waveguide, higher transmittance can be obtained, which is93.2%and90.29%respectively. At the same time, narrow bandwidth can also be achieved, that is6.4nm and2.9nm respectively. The size of entire device is about25μm×25μm, which provides potential value for future photonic integrated and all-optical communication.3) To decrease the threshold power and increase the sensitivity of all-optical switches as much as possible, we study a new all-optical switch by means of photonic resonant tunneling, which is based on the control of the parameters of resonant conditions. One way is to adjusting the optical distance between two photonic barriers. To do so, we add some nonlinear materials into photonic crystal waveguide and optimize the related parameters. At last, we design two kinds of switches controlled by light and present a qualitative analysis.