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Since the discovery of continuous, coherent THz radiation from intrinsic Josephson junctions (IJJs) constructed in the single crystals of Bi 2 Sr 2 CaCu 2 O 8+δ in 2007, various types of device structures have been developed. Thermal management of Joule heat in the IJJ mesa structure is the most important issue to improve the radiation characteristics of the IJJ-THz emitters. The radiation frequencies ranging from 0.3 to 2.4 THz, the emission power of $ \sim 30$ pW/mesa and the radiation linewidth of 0.2 GHz at $ \sim 0.5$ THz were obtained from the thermal managed device structures so far. We show a brief overview of the IJJ-THz emitters in our group.

We propose the mode dependent gain (MDG) reduction technique in few mode fiber amplifier using trench assisted GI fiber type long period grating. 1.8dB MDG reduction and wideband mode scrambling over 100nm are experimentally obtained.

We propose a method for a robot to manipulate an unknown door based on a single user instruction. The primary contributions of this paper are (i) to reduce the user instruction to a single click and (ii) to develop an efficient method to estimate an appropriate shape and manipulation model for a target door by integrating visual and touch information obtained by a robot. The proposed method first detects door candidates using a 3-D camera and then estimates the manipulation model of each candidate based on prior learning results. During door manipulation, the system integrates visual and touch information to estimate the shape and manipulation model to generate an appropriate motion. We evaluated the proposed method experimentally, and the results prove that the proposed method is effective.

There has been an increasing interest in mobile manipulators that are capable of performing physical work in living spaces worldwide, corresponding to an aging population with declining birth rates with the expectation of improving quality of life (QoL). Research and development is a must in intelligent sensing and software which will enable advanced recognition, judgment, and motion to realize household work by robots. In order to accelerate this research, we have developed a compact and safe research platform, Human Support Robot (HSR), which can be operated in an actual home environment. We assume that overall R&D will accelerate by using a common robot platform among many researchers since that enables them to share their research results. Currently, the number of HSR users is expanding to 33 sites in 8 countries worldwide (as of February 15, 2018). Software and technical knowledge of all users is shared through a community website. HSR has been adopted as a standard platform for international robot competitions such as RoboCup@Home and World Robot Summit (WRS). HSR is provided to participants of those competitions through public offering. In this paper, we describe HSR's development background, and technical detail of its hardware and software. Specifically, we describe its omnidirectional mobile base using the dual-wheel caster-drive mechanism, which is the basis of HSR's operational movement and a novel whole body motion control system. Finally, we describe the results of utilization in RoboCup@Home and field tests in order to demonstrate the effect of introducing the platform.

To reduce the size of electric power equipment and enhance its reliability, the electric field stress around spacer in gas insulated switchgear (GIS) should be considered. For the electric field relaxation to such a solid insulation system, a non-linear resistive material (NRM) seems effective. NRM is a composite of micro-varistor and epoxy, and it has excellent non-linear V-I characteristic. This paper deals with verification of the effect of NRM on the field relaxation using a model simulating epoxy spacer with NRM in comparison with metal embedded spacer. By embedding NRM under the electrode, the electric field of the triple junction (TJ) composed of the electrode, gas and insulator can be relaxed by 72 % under the impulse voltage (10 kV). In addition, it can also reduce the electric field concentration by 73 % at the embedded tip in AC voltage.

Recent progress on spatial-mode amplifiers is reviewed with a viewpoint of differential modal gain (DMG). The cascaded EDF, advanced cladding pumping, and randomly coupled multi-core EDF would be key technology for realizing the low DMG characteristic.

Alternately mode assigned multi-core EDF scheme is proposed for realizing the simple and power efficient wideband mode amplification. A 2.8 dB power efficiency improvement is confirmed for 3-mode amplification by optimizing the EDF design and sharing the pump source.

Remote-controlled daily assistive robots that can help handicapped individuals are expected to be a key technology in supporting aging communities. We present a method to simplify user instruction via a human-machine interface for robotic manipulation of various types of doors. Using our system, the user can teach the robot to open an unknown door by just a few clicks on an image generated from the robot's perspective. After the teaching stage, the robot is able to manipulate the door based on just a single user click on the position of the door handle, and an instruction determining if the door is to be opened or closed. The contributions of this paper to the research area are to (i) present a method to detect door candidates effectively from the point cloud of the surrounding environment using hypotheses on the plane and the shape of doors, to (ii) introduce a door feature to learn and remember the manipulation model, and to (iii) implement the system on a daily assistive robot and evaluate it. We tested our system on doors with various shapes and manipulation models, obtaining results supporting the effectiveness of our approach.

We reveal LP 02 mode has the lowest modal crosstalk in the longitudinal direction of four-LP mode pure silica core step-index fibre. 205 km unrepeated transmission over eight spools is successfully achieved using LP 02 mode selective launching.

We demonstrate a randomly-coupled 12-core EDF based cladding pumped optical amplifier for the first time. Flat gain of more than 17 dB with sufficiently low mode dependent gain of less than 1 dB over the full C-band is successfully realized.

A ring resonator based gain-clamped 4-LP mode EDFA is demonstrated for the first time. Low modal gain variation, less than 1 dB, is achieved for surviving channel for all modes when one of the modal channels is activated/deactivated.

This paper demonstrates a cross point Cu based Resistive Random Access Memory (Cu-ReRAM) technology suitable for Storage Class Memory (SCM) applications. Two key technologies have been developed for large capacity of 100Gb-class SCM with 100 ns program speed and 10M cycles of program endurance. One is tight resistance distributions of Cu-ReRAM by inserting a barrier layer to prevent excess intermixing. The other is a novel Boron and Carbon (BC) based Ovonic Threshold Switch (OTS) selector which meets requirements for large cross point arrays with low leakage current, low threshold voltage variability, and high endurance.

Stimulated Brillouin scattering (SBS), Brillouin lasing and SBS-coupled four-wave mixing were observed in an ultrahigh Q whispering gallery mode microbottle resonator fabricated on a single mode optical fiber.

Operating high-T c superconducting intrinsic Josephson junction emitters at 77 K, coherent and continuous THz EMWs with an intensity of several tens of μW can be generated, which provides us with sufficient power for the simple imaging operation. The frequency range may be extended widely as high as 2.4 THz from 0.4 THz. An example is given.

This study proposes the development of a simple remote-controlled daily assistive robot to assist physically challenged individuals. Specifically, we present a method for target object selection using a single click on a graphical user interface. Using this information, the robot can automatically estimate the unknown target object region to plan to grasp and fetch the object. The challenging task is to correctly estimate the region of the object of interest. The proposed system is implemented using the following framework for estimating the region of the object. First, the robot automatically estimates the object region based on user input. Second, the user can intervene by interactively drawing and erasing the estimated region while the system sequentially updates the estimation method based only on the user's correction. The advantage of this system is that only limited inputs are required from the user, a feature that is useful for handicapped users. Moreover, we introduce (1) graph cuts, comprising “HyperPixels” and three-dimensional information, to enable the system to recognize the rich features around the user-specified region for robust segmentation, (2) interactive correction of the automatically estimated object region while the system calculates good graph parameters for the correct estimation, and (3) recall and use of the learned parameters for the estimation based on the database of features around the clicked point.

We evaluate experimentally the nonlinear tolerance of two LP mode fibre with a low DMD and large A eff . We show experimentally that intra-wavelength XPM between modes affects MIMO transmission performance only slightly compared with SPM even with a low DMD.

We propose channel-dependent gain (CDG) reduction technique using single-core few-mode EDFA for multi-core transmission system. We investigate experimentally the proposed core-mode to LP-mode scrambled conversion characteristics using photonic lantern and realize low CDG independent of mode-dependent gain in EDFA.

We numerically and experimentally investigate the power transfer characteristics between super-modes in coupled multi-core fibre. We reveal that fibre twisting and bending considerably affect mode coupling and show how to suppress impulse response spread taking account of adiabatic/nonadiabatic mode conversion.

The influence of electrode position on the current-voltage characteristics (IVC) and broadly tunable terahertz (THz) radiation emitted from two pentagonal mesa structures consisting of the intrinsic Josephson junctions in a high-T c superconducting device is investigated.

We have fabricated and characterized a niobium titanium nitride (NbTiN)-based superconducting nanowire single- photon detector (SSPD or SNSPD) on the silicon (Si) waveguide toward the realization of waveguide-coupled SSPD. The superconducting critical temperature and critical current were 7.85 K and 34.4 μA at 0.3 K, respectively. We investigated the optical response of the fabricated device and found that the device exhibited a single-photon response. Furthermore, the fabricated device showed a clear bias current dependence of the output counts similar to conventional SSPDs.

Ba(Zr x Ti 1−x )O 3 (BZT) thin films with different Zr contents were deposited on (100)MgO and Pt/(100)MgO substrates by RF-magnetron reactive sputtering using metal targets. Coplanar and parallel plate capacitor structure with Pt/Au electrode based on BZT/MgO and BZT/Pt/MgO layer was fabricated by sputtering, photolithography, and etching processes. 500-nm-thick BZT thin films for high frequency performance showed a single perovskite phase and a high crystallinity on the MgO substrate with only a (001)/(100) orientation at an optimum deposition conditions. The BZT films had a stoichiometric Ba/Ti ratio and epitaxially grew on the MgO substrate. They showed a dense microstructure without cracks or voids. Dielectric properties of BZT thin films on (100)MgO substrates with different Zr contents (0 < x < 0.92) showed little dispersion at 1–40 GHz. Moreover, tunability of BZT thin film (x = 0.3) with parallel plate capacitor showed up to 43 % under 600 kV/cm. These results indicated that we succeeded in depositing high-quality and potentially tunable ferroelectric BZT films for high-frequency applications by RF-magnetron reactive sputtering using metal targets.

In this study, we carry out the heat shock test to the SiC MOSFET, and the thermal resistance change before and after the test were measured by transient thermal measurement. It was confirmed that the thermal resistance of the solder layer has increased after the test. From the results of the cross-sectional SEM observation, we found that delamination occurs in the interface of the solder layer and the chip. It was identified as the cause of increased thermal resistance.

This paper describes a modeling method that enables generation of a 3D shape model for movable parts of furniture and home appliances. Furniture such as refrigerators, shelves, and cabinets were targeted in this research. The proposed method is based on the tracking of 3D surfaces extracted from depth images captured by a 3D range camera. Both exterior and interior sides of an articulated part can be modeled as a 3D mesh model; moreover, the position of an articulated link can be estimated.

High-speed short-range wireless communication systems utilizing the 60-GHz band are expected. An installation of a 60-GHz transceiver into a mobile terminal with high packaging density is one of the promising usages. Electromagnetic noise in the mobile terminals is an important issue, because it may degrade the communication quality of the 60-GHz transceiver. This paper presents a novel antenna-in-package solution realizing both efficient radiation of millimeter waves and high shielding effectiveness to electromagnetic noises. The antenna is composed of U-shaped slots cut on the shielded ball grid array package. The antenna is designed to have a wide-angle radiation characteristic in the horizontal plane. The measured antenna gain of the fabricated antenna is from 2.9 to 5.2 dBi in the frequency range from 57 to 65 GHz.

We report novel FETs with a structure in which not only the top surface but also the side surfaces of island-shaped c-axis aligned crystalline indium-gallium-zinc oxide (CAAC-IGZO) serving as a channel are surrounded by a gate electrode, that is, surrounded channel CAAC-IGZO FETs. The FETs maintained their favorable subthreshold characteristics even if the channel length was scaled down to approximately 50 nm, i.e., normally-off, DIBL of 67 mV/V, SS of 92 mV/dec, and an off-state current lower than the measurement limit (0.1 pA) for a gate insulating film EOT of 11 nm. Moreover, we applied an FET with such a structure to a memory and discussed the writing time and the retention time, which were expected to be less than 5 ns and greater than 1,000 sec, respectively, for storage capacitance of 1 fF from circuit simulation.

A high-output power and broadband GaN high electron mobility transistor (HEMT) has been developed for X-band applications. The device consists of 2-dice of 14.4-mm gate periphery together with input and output 2-stage impedance transformers. The device exhibited saturated output power of 310 W with power gain of 10.0 dB over the wide frequency range of 8.5-10.0 GHz, operating at 65 V drain voltage under pulsed condition. In addition, the highest saturated output power reached 333 W with power gain of 10.2 dB at 9.0 GHz. This is the highest output power GaN HEMT ever reported for X-band.

In this paper, we present a simulation technique for a high-power module using silicon carbide (SiC) phase leg units. Each phase leg unit has parasitic inductances that are caused by bonding wires and patterns on a substrate in the phase leg unit. The parasitic inductances are extracted using a quasi-electromagnetic simulation tool. We also estimate mutual inductances between the parasitic inductances in the high-power module. We fabricate a high-power module that consists of six phase leg units with low parasitic inductance. Simulation results show a spike voltage of 156 V and a total parasitic inductance of 7.1 nH. Measurement results indicate a spike voltage of 154 V and a total parasitic inductance of 8.1 nH. These results show that the proposed technique is appropriate for predicting the switching performances of the high-power modules.

As concern for Japan's aging population and shrinking workforce continues to mount, many researchers are focusing on nursing and healthcare-related robots to help ease the burden on society. In order to successfully integrate robots into the home environment to coexist with family members, three features are considered essential: safe interaction, a compact and lightweight body, and a simple interface. In this paper the authors introduce a robot that possesses these qualities: the human support robot (HSR). The current prototype HSR is designed to support independent living of persons with limited limb mobility. This paper discusses the development of the HSR and the results of user testing conducted in the homes of two persons with disabilities.

The linearity has become more important to expand GaN HEMTs into microwave amplifier markets. This paper describes the outline of the large signal model of our 0.4μm AlGaN/GaN HEMT, considering the pulse biased 24 V operation. The analysis which utilizes the constructed Angelov model proved that the intermodulation distortion (IMD) of more than 10 dB backed off region is determined by the sub-threshold gm profile, namely steep rising gm profile degrades IMD. Thus, we proposed a thin n-GaN layer inserted buffer structure (ini-buffer), which realizes the significant IMD improvement of 8 dB, in the backed-off region.

PZT-based piezoelectric thin films will make better piezoelectric devices including piezoelectric energy harvesting (EH) power MEMS, when the piezoelectric thin films show high electromechanical coupling and/or high piezoelectric constants with low permittivity. The piezoelectric thin films are mostly polycrystalline structure with high piezoelectric constants and high dielectric constants, i.e. e*=300-1300 and e31,f = -8 ~ - 12C/m2. Recently we have found thin films of single c-domain/single crystal PZT-based ternary perovskite, Pb(Mn,Nb)-PZT, exhibit exotic properties, i.e. high coupling and/or high piezoelectric constants with low dielectric constants opposed to the PZT-based thin films. The relative dielectric constants are as low as 100 with e31,f = -12 C/m2. The low dielectric constants achieve high values of Figures of Merit for the EH-MEMS. This paper will discuss on the origin of the exotic dielectric and piezoelectric properties of the single c-domain/single crystal thin films in comparison with bulk PZT-based ceramics.

Tacit learning is the novel learning scheme based on the principle of biological control to create the appropriate behaviors adapted to the environment. Signal accumulation is the key factor for tacit learning in the process of behavior adaptation. To clarify the role of the signal accumulation in the learning process, we analyzed it dividing into the two processes depending on the control speed. The fast process is used for the behavior control and the slow process is used for the behavior adaptation to the environment. We developed the continuous-time controller for tacit learning with the integrators and showed that the signal accumulation can estimate a part of the robot model through the interactions between the robot body and the environment. This capability of tacit learning is useful to control a plant where the modeling errors and model changes are the critical problems for the stable controls. As the prominent example of the control of such plant, we experimentally verified that tacit learning can create the bipedal walking gait that pushes the ground by the support leg at the moment of losing contact with the ground.

In our recent studies, we demonstrated a conversion of a visible photon at 780 nm to a 1522-nm photon by using difference frequency generation. Intensity correlation measurement on the converted light confirmed that the non-classical property of the input single photon is retained over the conversion process. We further performed a conversion of one half of an entangled photon pair and observed a highly entangled photon pair at 780-nm and 1522-nm, which shows that the quantum information is really transferred in the quantum interface.

We report on intense, tunable, continuous, and coherent THz electromagnetic waves observed from differently shaped triangular mesas of the intrinsic Josephson junctions in single crystalline high-T c superconducting Bi 2 Sr 2 CaCu 2 O 8+δ . All samples are fabricated by focused ion beam milling.

Cu wire is drastically replacing Au wire due to surge of Au price. However, Cu wire package has poorer humidity reliability than Au wire package. Although Pd coated Cu wire package could show better humidity reliability than Cu wire, it is still worse than Au. Enough information regarding failure mechanism was not available. For failure analysis, x-section has been widely used to identify the Cu/Al IMC after failure. However, the x-section is the results of corrosion reaction and doesn't show the IMC status before corrosion. Therefore, the failure mechanism could not be estimated precisely. We used chemical model simulation to predict what kinds of IMC could be created after wire bonding, then which IMC could be corroded more easily during HAST. The Desorption energy was used to estimate reactivity between specified Cu/Al IMC and chlorine ion. The simulation suggested that the formation of Cu rich and Cu poor Cu/Al IMC and the Cu rich IMC was estimated to be corroded by chlorine ion. These chemical model simulations are the effective way to have fundamental understanding of the mechanism of Cu/Al IMC corrosion. Furthermore, chemical model simulation for Pd coated Cu wire was done to explore the effect of Pd existence and distribution of Pd in Cu/Al IMC. Dispersed Pd contributed to create new IMC of Cu/Al/Pd instead of easily corroded Cu rich Cu/Al IMC. Cu and Al diffusion and also Cl ion diffusion were inhibited by Pd at surface. Even Cl ion catching effect by Pd is also discussed. To improve humidity reliability performance with Cu wire, we developed new ion trapper using chemical model simulation technique. Developed molding compounds with the ion trapper showed significant improvement at bias HAST with Cu wire, which was even better than conventional Cu wire compatible molding compounds.

This paper proposes a new method to suppress interference using antenna array for LTE uplink. The proposed method does not require knowledge on resource allocation of either interfering or communicating mobile stations, and thus it has a significant advantage of ease of implementation. An additional advantage of this method is parallelization and scalability for multi-core processing. This paper also proposes a novel iterative timing offset compensation to enable effective interference suppression. The proposed method has been successfully implemented on System-on-Chip consisting of multi-core DSP and ARM microprocessors and verified that it successfully suppresses interference in real time.

In this paper, we present an asymmetrical Doherty amplifier (DA) that can enhance the efficiency at a 9.5 dB backoff from its saturated output power (P SAT ). The asymmetrical DA consists of a peak amplifier and a carrier amplifier with two and one 210 W gallium nitride (GaN) high-electron-mobility transistors (HEMTs), respectively. A Wilkinson combiner at the output of the peak amplifier enables the stable operation of the GaN HEMTs for high-power applications. The asymmetrical DA is designed and fabricated for the ultrahigh-frequency (UHF) band. Measurement results using a continuous wave (CW) signal indicate a drain efficiency (η d ) of 60% at a P SAT of 57.5 dBm and a η d of 56% at a 9.5 dB backoff from P SAT . For a 6 MHz orthogonal frequency-division multiplexing (OFDM) signal with a high peak-to-average power ratio (PAPR), the measurement results indicate a η d of 52% and an adjacent-channel leakage power ratio (ACLR) of −41 dBc at an average output power (P AVE ) of 48 dBm using a digital predistorter. To the best of our knowledge, this is the highest η d and output power for an OFDM signal.

This paper describes methods of environment map representation and plane detection for daily assistive robots. Under the assumption that 3D information of around environment is constructed by collecting range data gradually measured, we propose an effective map representation named TCCM (Time-series Composite Cuboid Map). The method copes with temporal sequence explicitly, and map updating is efficiently performed. In addition, two plane estimation methods are proposed. Through several experiments in daily environments, we ensured the effectiveness of our method.

This paper describes about online collision and occlusion detection for a daily assistive robot. It is assumed that 3D map about around environment is constructed by collecting datasets gradually measured using a Laser RangeFinder mounted on a tilting platform, we develop an approach to detect collision and occlusion based on the 3D map while a robot tries to manipulate objects in daily environment. As the map representation, Time-series Composite Cuboid Map is proposed. It copes with temporal sequence explicitly, and map updating is efficiently performed. Several experiments on the assumption of daily assistance by a robot, we show the effectiveness of our approach.

In this paper, we present a high-efficiency 300 W Doherty power amplifier (DPA) that can improve the efficiency at an 8 dB backoff from its saturated output power (P SAT ). To enhance the efficiency, asymmetrical drain voltages are supplied to a carrier amplifier and a peak amplifier in the DPA. The drain voltages and radio frequency (RF) circuit parameters of each amplifier are determined by basic load-impedance analysis. The DPA is fabricated using a push-pull laterally diffused metal oxide semiconductor (LDMOS) field-effect transistor (FET) for an ultrahigh frequency (UHF) band. The drain voltages are set to 50 V and 30 V. Measurement results using a continuous wave (CW) signal indicate a drain efficiency (η d ) of 50% at a P SAT of 55 dBm and a η d of 48% at an 8 dB backoff from P SAT , which means that the proposed DPA can extend the power range in which its highest efficiency is maintained. For a wideband code division multiple access (W-CDMA) signal with a peak-to-average power ratio (PAPR) of 8 dB, the measurement results indicate a η d of 43% and an adjacent-channel leakage power ratio (ACLR) of −23 dBc at an output power of 47 dBm.

Multi-Gbps transceivers have evolved from what were once exotic special-purpose cells to ubiquitous building blocks that are expected to function as the glue bet ween critical compute, communications, and storage elements. As such they are expected to function flawlessly, interoperate cleanly, and consume little power, area, and system design mindshare. As part of the 'commoditizing' of transceivers, the pressure to achieve multiple standards compliance from individual designs has increased dramatically no longer are ASIC or system designers content with a single PHY for a single standard. The consequential impact on the design space means link designers must often 'right size' a swiss-army-knife design including power and area optimization; you don't want too many or too few 'blades'. Sometimes conflicting standards requirements can make customization and optimization a real challenge in this space. Jared Zerbe of Rambus will review some of the fundamental transceiver challenges and techniques used to address them, including a discussion of the impact of multi-standard compliance on the transceiver design effort and ultimate performance. Following this, Thomas Toifl of IBM will discuss the design challenges and solutions to data rates above 20Gb/s. Main challenges are achieving the required bandwidth with full ESD protection, the DFE loop timing, and overall design complexity. Marcus van lerssel of Snowbush IP will discuss implementation challenges and the benefits of a multi-standard PHY supporting Ethernet/PCIe/SATA/USB. Takeshi Horiefrom Fujitsu will present Ethernet standards and the technologies required to realize 10GB serial backplane transfer for 10GB Ethernet. When it comes to buidling standards compliant PHYs, IP providers face challenges that arise from the need to proliferate the design across many process geome tries/foundries and also from the large variability in customer's expertise in package design and signal integrity analysis. Dan Weinlader of Synopsys will discuss how standards influence these challenges. The main focus of standards over the last few years has understandably been on addressing the bandwidth curve. The need to address the rising power struggle of SoCs is usually recognized, but limited to simple power targets. The final two presentations in this forum will focus on energy efficiency by Fulvio Spagna of Intel and on low-power solutions by Anthony Sanders of Lantiq.

In this paper, we present a millimeter-wave microelectromechanical systems (MEMS) switch with a microsecond switching time. The optimization of the mechanical structure, application of high actuation voltages and encapsulation with a vacuum-sealed package result in a higher speed with which a beam of the MEMS switch is pulled in and pulled out. In order to reduce the packaging cost, we encapsulate the MEMS switch using an in-line wafer level package (WLP) which is built during the same complementary metal-oxide semiconductor (CMOS) process in which the MEMS switch is built. The fabricated MEMS switch is a shunt circuit and capacitive contact type. The dimensions of the in-line WLP are 500 µm wide by 500 µm long. The measurement results show an insertion loss of 0.5 dB and an isolation of 15 dB at a frequency of 50 GHz. The measured switching time is 2.0 µs or less. This is the shortest switching time of a MEMS capacitive switch for millimeter wave applications as far as the authors know.

We generated 15 carriers with a 50-GHz spacing in the O-band using an optical frequency comb technique and a Fabry-Perot filter. We demonstrated a 10 Gbps × 15 DWDM transmission over a 24-km PCF.

In this paper, we propose an adaptive array to suppress interference signals for uplink OFDMA in mobile WiMAX. Uplink user data is distributed over the bandwidth and the channel state changes instantly so it is difficult to apply a conventional algorithm. To solve this problem, adaptive weight is calculated on a "tile-by-tile" basis in the proposed method. In our simulation and experiments, compared to conventional Zero- Forcing (ZF) algorithm, the proposed algorithm can realize better reception quality.