A special class of anisotropic media -hyperbolic metamaterials and metasurfaces (HMMs) -has attracted much attention in recent years due to its unique abilities to manipulate and engineer electromagnetic waves on the subwavelength scale. Because all HMM designs require metal-dielectric composites, the unavoidable metal loss at optical frequencies inspired the development of active HMMs, where gain material is incorporated to compensate the metal loss. Here, we experimentally demonstrate an active type II HMM that operates at vacuum wavelengths near 750 nm on a silicon platform. Different from previous active HMMs operating below 1 𝝁𝒎 , the dielectric constituent in our HMM is solely composed of gain medium, by utilizing solution-processed and widely tunable metal-halide perovskite gain. Thanks to the facile fabrication, tunability and silicon compatibility of our active HMM, this work paves the way towards HMM's integration into on-chip components, and eventually, into photonic integrated circuits.

Solution‐processed organic–inorganic metal halide perovskites have recently attracted tremendous attention in the photodetector community due to their excellent optoelectronic properties and facile fabrication. The main challenge in perovskite photodetectors (PSPDs) is to achieve high responsivity and fast speed simultaneously. In this work, this challenge is overcome by employing a directly patterned nanograting methylammonium lead iodide (MAPbI3) film in metal‐semiconductor‐metal (MSM) PSPD on interdigitated indium tin oxide (ITO) electrodes. Because of the improved perovskite morphology after directly patterning by nanoimprint lithography, as well as the enhanced electric field intensity by the perovskite nanograting and interdigitated electrodes, the PSPDs have responsivity of 441 A W−1, detectivity of 8.32 × 1012 Jones, response time of 10.7 µs, all of which are among the best performances in MSM PSPDs. Moreover, the PSPDs maintain excellent photocurrent performance after 20 days of air exposure. The approach opens a path to manufacturing‐friendly, high‐performance, and reliable PSPDs and paves the way toward perovskite‐based optoelectronic circuits.

Will-beset by IN -TECH transmit/receive turnaround times in the nanosecond regime. Integrated front-ends which successfully address this issue are presented here for the first time. The second section deals with signal processing. As, due to the large RF bandwidth, direct analog to digital conversion and digital signal processing are not feasible (at least not at reasonable power consumption), analog signal processing is one focus. For communication, detection methods based on analog correlation require channel estimation, storing of impulse responses and also precise time synchronization. Therefore methods based on energy detection are developed which require no or little channel knowledge, having low complexity, robustness to multipath propagation and high resistance to synchronization and symbol clock errors. New modulation techniques are described, which can cope with interchip and intersymbol interference. Also a novel support by a comb filter resulting in significant SNR improvements in interference and multiuser scenarios is presented. The methods developed for communication applications can also be used in the radar context. For detection and tracking of moving targets (e.g. heart in the body) new algorithms based on particle filtering are developed for the digital signal processing part. It is shown that the accuracy, the resolution and robustness can be improved compared to conventional methods. For the objective of catheter localization, the knowledge of the shape and position of the human body surface is inevitable. A UWB imaging algorithm for the detection and estimation of this surface has been developed based on trilateration and is also described in this second section. Furthermore, building on this surface estimation algorithm, a new method for the localization of transmitters in dielectric media is presented. Taking into account the refraction effects on the boundary surface, the algorithm uses the impulse time of arrival to determine the transmitter position inside of the dielectric medium. The third section finally describes the design of bistatic UWB radar systems using the components presented in the first section. Single-ended and differential radar demonstrators are developed, with which the potential of impulse-radio UWB sensing is evaluated. Measurements aimed at applications of the developed hardware such as vital sign monitoring and communication with implants are presented. Further measurements are performed to prove the functionality of the imaging algorithms derived in the second section. For surface estimation, a single radar sensor is moved around a highly reflective target in order to emulate a whole sensor array. For the verification of subsurface transmitter localization, a transmitter is placed inside of a container filled with tissue mimicking liquid, and its position is visualized with respect to the estimated container surface. 2. Circuit and component design 2.1. UWB antennas Concepts for antennas with an ultra-wideband behavior are well-known and established [30]. However...

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