Large scale Data Centers (DC) and High Performance Computing (HPC) systems require more and more computing power at higher energy efficiency. They are already consuming megawatts of power, and a linear extrapolation of trends reveals that they may eventually lead to unrealistic power consumption scenarios in order to satisfy future requirements (e.g. Exascale computing). Conventional CMOS-based electronic interconnects are not expected to keep up with the envisioned future board-to-board and chip-to-chip (within multi-chip-modules) interconnect requirements because of bandwidth-density and power-consumption limitations. However, low-power and high-speed optics-based interconnects are emerging as alternatives for DC and HPC communications; they offer unique opportunities for continued energy-efficiency and bandwidth-density improvements, although cost is a challenge at the shortest length scales. Plasmonics-based interconnects on the other hand, due to their extremely small size, offer another interesting solution for further scaling operational speed and energy efficiency. At the device-level, CMOS compatibility is also an important issue, since ultimately photonics or plasmonics will have to be co-integrated with electronics. In this paper, we survey the available literature and compare the aforementioned interconnect technologies, with respect to their suitability for high-speed and energy-efficient on-chip and off-chip communications. This work refers to relatively short links with potential applications in the following interconnect distance hierarchy: local group of racks, board to board, module to module, chip to chip and on chip connections. We compare different interconnect device modules, including low-energy output devices (such as lasers, modulators and LEDs), photodetectors, passive devices (i.e. waveguides and couplers) and electrical circuitry (such as laserdiode drivers, modulator drivers, transimpedance and limiting amplifiers). We show that photonic technologies have the potential to meet the requirements for selected HPC and DC applications in a shorter term. We also present that plasmonic interconnect modules could offer ultra-compact active areas, leading to high integration bandwidth densities, and low device capacitances allowing for ultra-high bandwidth operation that would satisfy the application requirements further into the future.

This paper presents the design and fabrication of a fiber-optic refractive index (RI) sensor. The novel concept employs a long-period fiber grating (LPG) to achieve surface plasmon resonance (SPR) of a single cladding mode at the gold-coated tip of a single-mode fiber. The sensor combines a high level of sensitivity, a miniaturized sensing area and simple intensity-based interrogation, and is intended for biosensing using portable point-of-care devices or highly integrated lab-on-chip systems.

This paper presents an ultra-miniaturized implant antenna with a volume of 22.22 mm ³ in the Medical Implant Communication Service (MICS) frequency band 402-405 MHz to be integrated with a leadless cardiac pacemaker. The proposed antenna has a planar spiral geometry with a defective ground plane exhibiting a radiation efficiency of 3.3% in the lossy medium with more than 20 dB of improved forward transmission, while the coupling can be further enhanced by adjusting the thickness of the antenna insulation and the antenna size according to the application area. The implanted antenna demonstrates a measured bandwidth of 28 MHz, covering beyond the MICS band needs. The proposed circuit model of the antenna describes the different behaviors of the implanted antenna over a wide bandwidth. The antenna interaction within human tissues and the improved behavior of the electrically small antenna are explained in terms of radiation resistance, inductance, and capacitance that are obtained from the circuit model. The results are demonstrated using electromagnetic computations and are validated by the measurement using liquid phantom and animal experiments.

This letter presents a bondwire model in the form of a lumped-element network, which is based on the geometry of the bondwire and landing pads. For the interconnection between a chip and the feedline on a printed circuit board (PCB) substrate, the associated parasitics are calculated, which are responsible for the performance degradation caused by the bondwire at millimeter-wave (mmWave) frequencies. A matching network is realized with planar-lumped elements on the PCB and integrated for impedance mismatch compensation at a center frequency of 60 GHz. Simulations show an operating bandwidth of 50–70 GHz. The proposed solution is first verified by the measurements of PCB-to-PCB bondwire interconnects. Then, as an application example, an antenna-switch chip is placed at the PCB feedline. Remarkable improvements in terms of input matching and insertion loss are observed compared with an unmatched bondwire interconnect.

In this letter, we propose fundamental path loss (PL) models which play vital roles in promoting the intraheart communication system design of future deeply implanted leadless pacemakers inside the cardiac chambers. Initially, employing a plane wave approach yields the attenuation of the electric field in homogeneous heart tissue, while a modified Friis equation in the lossy medium is utilized to evaluate the power transmission between transmitting and receiving antennas in homogeneous heart tissue in the far-field zone. An Hertzian dipole excitation is used to separate the mismatch and ohmic losses of the antenna from the path loss in an anatomical human body simulation environment. Based on this theoretical and full-wave simulation setup, PL models are derived and comprehensively compared at different potential frequency bands [Medical Implant Communication Service (MICS) 402-405 MHz, Wireless Medical Telemetry Service (WMTS) 608-614 MHz, Industrial, Scientific, and Medical (ISM) 867-869 MHz, and 2400-2500 MHz], and the validity of applying the Friis equation in this scenario is verified.

This paper presents in-body to on-body and in-body to in-body channel models of a planar wideband elliptical ring implanted antenna in the lower part of Ultra-WideBand (UWB, 3.1 to 5.1 GHz). The results are verified inside a practical UWB liquid phantom with the help of a wideband on-body monopole antenna. Moreover, the design principle of the in-body and on-body antennas, as well as their simulated and measured reflection coefficients are presented. The channel characterization inside the lossy medium gives a deep insight of wireless capsule endoscope technology (WCE) and helps to evaluate the radiation performance of the previously designed planar elliptical ring implanted antenna.