Coherent Control Of Polarization Conversion Properties Of Chiral Metamaterials

Today's telecommunications networks are still largely optically opaque–consisting of electronic nodes connected by point-to-point optical links,relying on a series of optical-electrical conversions.Moving to all-optical switching will allow increased bit rates and low latency movement of data,providing greater routing agility,reducing energy requirements and simplifying network structures.This promise,and indeed the fact that the fundamental capacity limits of existing infrastructure are being reached,has sparked renewed interest in the extension of telecommunications bands to longer infrared wavelengths(where lower intrinsic losses in fibre media are possible).Future network architectures will require a new generation of highly integrated devices capable of functions such as all-optical switching and mode(de)multiplexing.In the thesis,the double cross metamaterial and asymmetric split-ring metamaterial were studied respectively.The results show that double cross metamaterial can be used the tunable polarization converter and coherent absorber.The tunable change of the asymmetric transmission effect is achieved by the coherent control of the asymmetric split-ring metamaterials.The main tasks as follows:1.In this paper,we design a double cross metamaterial and prove that the structure can achieve good absorbing phenomenon When a single beam of light is incident,whether the X-polarized light or the Y-polarized light is used to irradiate the metamaterial,nearly 20% of the polarization conversion effect and the 50% absorption effect can be achieved near 6.9GHz.Then the structure is further studied by means of coherent control.The results show that when the phase difference between the two beams is 0?,the absorption of the structure can be kept below 10%,which is close to completely transparent;When the phase difference between the two beams is 180?,the absorption effect of the structure can be increased to 90%,which is close to perfect absorption.2.Coherent control of asymmetric transmission effects in asymmetric split-ring metamaterials is studied.The result shows that when single beam of light is incident,both left-handed and right-handed light can achieve asymmetric transmission performance of transmission,reflection and absorption near 5.5 GHz.The asymmetric transmission coefficients of transmission,reflection and absorption are respectively 20%,20% and 30%.Then we further study the structure by means of coherent control.This investigation shows that the asymmetric transmission effect of the metamaterials can be dynamically adjusted by adjusting the phase difference between the two incident lights,so that the asymmetric transmission coefficient of the transmission is a cosine curve between-0.3 and 0.3,and the absorbed asymmetric transmission coefficient is sinusoidal between-0.3 and 0.3.Therefore,through the above research,it can be inferred that by applying the method of coherent control,some singular properties in superstructure materials can be improved and the controllability of superstructure materials can be increased.