Abstract
Metamaterials are a new class of artificial electromagnetic materials in which the building elements are smaller than the wavelength of illuminating light and arranged in the orders of natural atoms. They possess unprecedented electromagnetic responses such as high frequency magnetic responses, an ultra-low plasmonic frequency and negative refraction index, which are all rare or even not existing in nature. Moreover, metamaterials can further manipulate and control light by designing their unit cells instead of their constitutive materials. In this dissertation, we would design three remarkable metamaterials to approach applications such as an ultrabroad filter, slowing light devices and the innovative cloak. First of all, no matter in electronic or photonic devices, a filter is a crucial component to select signals from noises. However, it becomes a challenge to design filters especially for much higher frequency ranges. As an example, to design a filter in the unlicensed 60 GHz frequency range, we combine the right-handed response from nature materials and the left-handed response from metamaterials to form a composite right/ left-handed filter. The filter possesses the effective bandwidth of 20 GHz, the band-edge transitions of 250 dB/10 GHz, and the transmission efficiency above -1 dB, which accomplish the high quality factor and large effective bandwidth simultaneously. Next, due to much weaker interaction between electromagnetic waves and materials compared to the one between electrons and materials, it is difficult to manipulate information carried by photons. Thus, we employ negative Goos- Hänchen effect to detour photons around the critical thickness of the negative refractive waveguide composed of a multiple incidence metamaterial and slow down the speed of photons effectively to enhance the interaction time between photons and materials. Further, we can even store energy of photons in the waveguide completely as a light storage medium. Finally, to design the optical path is also an important issue in optics. For example, an optical fiber might lose its signals when the fiber is bent or twisted. To avoid unnecessary losses, researchers employ transformation optics to distort the coordinate systems to render that optical signals transmitting through a bent fiber insusceptibly. Here, we will demonstrate an innovative cloak of invisibility as an example to validate the robustness of transformation optics and also we bring in the concept of complementary medium in the design procedure to enable the cloak to conceal arbitrary multi-objects with movements and visions.