In this paper, an ultra-wideband and polarization-independent metasurface for radar cross section (RCS) reduction is proposed. The unit cell of the metasurface operates in a linear cross-polarization scheme in a broad band. The phase and amplitude of cross-polarized reflection can be separately controlled by its geometry and rotation angle. Based on the diffuse reflection theory, a 3-bit coding metasurface is designed to reduce the RCS in an ultra-wide band. The wideband property of the metasurface benefits from the wideband cross polarization conversion and flexible phase modulation. In addition, the polarization-independent feature of the metasurface is achieved by tailoring the rotation angle of each element. Both the simulated and measured results demonstrate that the proposed metasurface can reduce the RCS significantly in an ultra-wide frequency band for both normal and oblique incidences, which makes it promising in the applications such as electromagnetic cloaking.
A novel scheme for implementing high-performance optical single-sideband (OSSB) modulation based on a dual-drive Mach-Zehnder modulator (MZM) and a 120°hybrid coupler is proposed and demonstrated. A RF signal is divided by the 120°h ybrid coupler into two parts with equal powers and a phase difference of 120°, and then, led to the two RF ports of the dual-drive MZM. With a proper dc bias, an OSSB signal with the −1st and +2nd-order sidebands (or the +1st and −2nd-order sidebands) suppressed is generated. A numerical simulation and a proof-ofconcept experiment are carried out. As compared with the conventional OSSB modulation based on a 90°hybrid coupler, the suppression of the +2nd (or −2nd)-order sideband improves evidently the performance when the OSSB modulation is applied in a radio-over-fiber system or an optical vector network analyzer.Index Terms-Microwave photonics, optical single-sideband (OSSB) modulation, optical vector network analysis, radio-overfiber (RoF).
In this work, we demonstrate that composite spoof surface plasmon polaritons can be excited by coplanar waveguide, which are composed of two different spoof surface plasmon polaritons (SSPPs) modes propagating along a periodically corrugated metallic thin film simultaneously. These two SSPPs correspond to the dominant modes of one-dimensional (1D) periodical hole and groove arrays separately. We have designed and simulated a planar composite plasmonic waveguide in the microwave frequencies, and the simulation results show that the composite plasmonic waveguide can achieve multi-channel signal transmission with good propagation performance. The proposed planar composite plasmonic metamaterial can find potential applications in developing surface wave devices in integrated plasmonic circuits and multi-channel signal transmission systems in the microwave and terahertz frequencies.
Optical vector network analyzers (OVNAs) based on optical single-sideband (OSSB) modulation are of great interest thanks to the potentially high measurement resolution. However, the measurement accuracy of the OSSBbased OVNA is limited by the high-order sidebands in the OSSB signal. To study the influence of the high-order optical sidebands in OSSB signals on the measurement accuracy, an analytical model is established to present the expression of the measurement error and a numerical simulation is performed. For the OSSB-based OVNA implemented by a 90-deg electrical hybrid coupler and a dual-drive modulator, when the −1st order sideband is fully suppressed by the OSSB modulation, the existence of the 2nd-order sideband severely degrades the resolution of the measurement, while the −3rd and −2nd order sidebands place a restriction on the dynamic range of the measurement. In addition, these sidebands also introduce evident measurement errors to the phase response. The study may provide a good guidance in designing the high performance OVNA.
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