Simple equivalent systems for GRIN lenses in inhomogeneous medium

Simple single-lens equivalent systems for graded-index （GRIN） lenses in inhomogeneous medium obtained using matrix optics are proposed in this letter. Due to its simplicity, the equivalent optical system enables quick analysis of the imaging properties of GRIN lens rod immersed in inhomogeneous medium. This facilitates the optical analysis of complicated optoelectronics systems in inhomogeneous medium utilizing GRIN lens rods.     

基于开环振荡器阵列磁振荡效应的全光开关

We demonstrate an all-optical switching of the magnetic resonance properties associated with a metallic Split Ring Resonator（SRR） array. The periodically spaced elements are fabricated on a high-resistivity silicon wafer and probed by using conventional Terahertz （THz） time-domain spectroscopy. We use a continuous-wave laser diode to generate carriers in the gaps of the SRR elements. Using a sufficient power, this opti- cal excitation can create an effective short gap, which would switch the resonant properties of the metamaterial from that of an SRR array to that of a closed ring resonator array and leads to dramatic changes in the THz transmission. In the present experiment, the optically induced switching is associated with the magnetic reso- nance. However, with appropriate changes in the device structure, this approach can be extended to switch a medium with a negative real index of refraction to a medium with a positive real index of refraction. This opens the way to creat a broad new range of active devices.