Optical Cloaking And Cloak Detection In The Frame Of Transformation Optics

Recently many interesting have been reported in Transformation Optics. The concept of Transformation Optics has enabled the design of new anisotropic, spatially inhomogeneous materials that can steer light along arbitrary curves by coordinate transformation mathematically. The implementation is made possible by employing metamaterials. Among various novel applications, the most fascinating is a cloaking device designed to bend light around a concealed region, rendering any object inside the region "invisible". Further, the method of Transformation Optics can also be used on the acoustic wave and matter wave. Our work focus on the following two parts:First, we demonstrate a unique approach for watching outside while hiding under a carpet cloaking based on transformation optics. Unlike conventional carpet cloaking, which screens all the incident electromagnetic waves, we break the cloak and allow incident light get into the carpet. Hence outside information is detected inside the cloak. To recover the invisible cloaking, complementary techniques are applied in the broken space. Consequently, a hiding-inside and watching-outside (HIWO) carpet cloak is sewed, which works as an invisible cloaking and allows surveillance of the outside at the same time. Our work provides a strategy for an ideal cloak with "hiding’ and "watching" functions simultaneously.Second, based on transformation optics, we propose a device to detect the presence of a carpet cloaking structure at near field. By using complementary media, the detective device can optically cancel a certain volume of reflective metal and reveal the hidden medium inside the metal. The detective performance of this device is confirmed by full-wave finite-element simulations. It is shown that the detective device is invisible when there is no carpet cloak in the system, yet it becomes visible with the presence of the carpet cloak. The device works at near field, but the response can be found even at the far field. Furthermore, it is shown that the device can detect both anisotropic and isotropic carpet cloaking structures. The investigation may provide a unique method to detect a carpet cloak and contribute to the design of novel optical devices.To sum up, we study the theory of transformation optics. We also propose new methods in designing functional device by using transformation optics. The findings provide scientific basics for developing new electromagnetic materials as well as opening new perspective in manipulating the electromagnetic waves.