Ultra low loss polymer waveguides

1200 V / 200 A V-groove trench MOSFET optimized to achieve low power loss, high oxide reliability under a drain bias condition and high avalanche ruggedness is shown in this paper. We revealed a relationship between the lifetime under a high temperature reverse bias condition and the oxide electric field. In accordance with the results of the test, the 1200 V / 200 A trench MOSFET showed an improvement in the tradeoff between the on-resistance and oxide electric field with the presence of current spreading layers. In order to obtain low on-resistance and high avalanche ruggedness at the same time, buried guard ring structures, which made the blocking voltage of the edge termination area higher than that of the active area, was developed. The fabricated MOSFETs demonstrated a low specific on-resistance of 3.1 mΩ cm2. A predicted lifetime of 200 years under a high temperature drain bias condition of 1200 V was achieved by the optimized design. A short circuit withstand time of 6 μs and a high avalanche energy of 7.8 J/cm2 were shown.

An attempt has been made to fabricate and analyze the transmission of microwave power and bandwidth through an X band waveguide window filled with a material having high dielectric constant and low dielectric loss. In this study, the single phase Ba(Zn 1/3 Ta 2/3 )O 3 (BZT) BZT material is synthesized through solid-state reaction method. The microwave dielectric properties of BZT samples measured using Vector network analyzer with Hakki-Coleman setup. The obtained dielectric properties used to fabricate the dielectric window in waveguide structure and dielectric window is simulated using a finite difference time domain (FDTD) based software (IMST's Empire). The simulation work is carried out by varying thickness of ceramic window while keeping dielectric constant and loss tangent fixed to study the effect of window thickness on power transmission. The dielectric constant effect on power transmission is also studied by varying dielectric constant while keeping the window thickness constant. The maximum power transmission obtained for a BZT window of thickness 2.85mm at 10 GHz with bandwidth of 2.07 GHz corresponds to a S 21 magnitude of 0.019 dB and return loss at the same frequency is −48dB.

Low loss, long time stable sol–gel derived silica–titania waveguide films

In this paper, a novel method for designing high-power filtering switches using dielectric resonators (DRs) is presented for the first time. The filtering switches consist of DRs and printed circuit boards. The latter are embedded in the metal cavity to enable the integration of p-i-n diodes. The ON- and OFF-states are realized by controlling the p-i-n diodes which are put in the feeding lines or nonresonance nodes (NRNs). Electromagnetic field properties of the DR (at TE $_{11\delta }$ mode) and feeding line (or NRN) are studied and the coupling between them is investigated for guiding coupling control. In the ON-state, the filtering switches are equivalent to bandpass filters with no signal passing through the p-i-n diodes, which avoids additional loss introduced by p-i-n diodes and attains high power handling capability. In the OFF-state, the proposed filtering switches offer enhanced isolations by controlling the coupling of the filtering circuits, which differs from the conventional switches by turning off transistors or diodes. For demonstration, a DR-based filtering single-pole single-throw switch and a filtering single-pole double-throw switch are implemented. High selectivity, low ON-state loss and high OFF-state isolation are observed. The measured $\text{P}_{\mathrm {1dB}}$ is larger than 80 W, featuring high power handling capability.

There is an ever-increasing need by semiconductor/packaging companies for the introduction of a low loss, ultra-low Coefficient of Thermal Expansion chip carrier packaging substrate core material that provides a cost-effective method for producing thin core build up with very dense core vias. This low loss, low CTE flip-chip substrate core is well suited to multi-layer, RF, and applications requiring a system-in-package approach. This paper discusses a novel substrate core material using a build-up film dielectric layer in conjunction with glass fiber weave. Key properties include low loss (Df<0.002), a CTE from 5 - 10 ppm/C, extremely high thermal reliability, and low modulus. An advantage of using glass fiber weave instead of Invar, for instance, is the extremely low CTE that can be achieved while still maintaining a non-conductive power or ground plane. Multilayer circuits using PTFE can suffer from extremely high lamination temperatures, high cost, and low overall yields due to the inability of the soft material to go through a desmear process. Substrate core materials have the primary benefit that they offer stability and increased reliability of many subsequent build-up microvia layers. As monolithic semiconductors are replaced by chiplets, there is a growing need to package many types of chiplets without losing the signal integrity performance of a monolithic semiconductor on a single IC package. An extremely low loss substrate core offers the potential benefit that unique chiplet packaging architectures can be designed with the lowest possible dielectric losses due to the multichip interconnect strategy.

The proliferation of multimedia content and the demand for new audio or video services have fostered the development of a new era based on multimedia information, which allowed the evolution of Wireless Multimedia Sensor Networks (WMSNs) and also Flying Ad-Hoc Networks (FANETs). In this way, live multimedia services require real-time video transmissions with a low frame loss rate, tolerable end-to-end delay, and jitter to support video dissemination with Quality of Experience (QoE) support. Hence, a key principle in a QoE-aware approach is the transmission of high priority frames (protect them) with a minimum packet loss ratio, as well as network overhead. Moreover, multimedia content must be transmitted from a given source to the destination via intermediate nodes with high reliability in a large scale scenario. The routing service must cope with dynamic topologies caused by node failure or mobility, as well as wireless channel changes, in order to continue to operate despite dynamic topologies during multimedia transmission. Finally, understanding user satisfaction on watching a video sequence is becoming a key requirement for delivery of multimedia content with QoE support. With this goal in mind, solutions involving multimedia transmissions must take into account the video characteristics to improve video quality delivery. The main research contributions of this thesis are driven by the research question how to provide multimedia distribution with high energy-efficiency, reliability, robustness, scalability, and QoE support over wireless ad hoc networks. The thesis addresses several problem domains with contributions on different layers of the communication stack. At the application layer, we introduce a QoE-aware packet redundancy mechanism to reduce the impact of the unreliable and lossy nature of wireless environment to disseminate live multimedia content. At the network layer, we introduce two routing protocols, namely video-aware Multi-hop and multi-path hierarchical routing protocol for Efficient VIdeo transmission for static WMSN scenarios (MEVI), and cross-layer link quality and geographical-aware beaconless OR protocol for multimedia FANET scenarios (XLinGO). Both protocols enable multimedia dissemination with energy-efficiency, reliability and QoE support. This is achieved by combining multiple cross-layer metrics for routing decision in order to establish reliable routes.

We report on the development of a new generation of very high power 980 nm single lateral mode ridge-waveguide quantum-well lasers. An asymmetric-waveguides vertical structure has been optimized for very low internal losses while keeping the vertical mode-size large, thus allowing a low vertical far-field beam angle of less than 19°. Careful optimization of the doping profiles, and epitaxial interfaces optimization for reduced scattering, allowed to obtain internal losses as low as 0.6-0.7 cm^-1. Such low losses are necessary to keep the external efficiency high in very long cavities, together with a high internal quantum efficiency. We thus reached our goal of keeping the external efficiency above 70% even for cavity lengths of 4.5 mm. The flared ridge waveguide has been designed to strongly filter higher order lateral modes, and kink-free operation has been obtained up to over 1.5 W output power, with very stable vertical and horizontal beam patterns. High saturation powers above 2 W have also been demonstrated at 25°C, and over 1.5 W at 75°C. Wavelength stabilized chips, by means of a fiber Bragg grating, reached linear fiber powers above 1.0 W with strong suppression of gain-peak lasing at all currents and good power stability.

A novel 1.7kV IGBT with deep floating-p layers separated from trench gates has been developed to realize low loss, low EMI noise, and high reliability. Separating floating-p layers from the trench gates reduces excess V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GE</sub> overshoot, which results in a 51% smaller reverse recovery dV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AK</sub> /dt than the conventional IGBT. The deep floating p-layers weaken the electric field under the trenches, which results in an avalanche breakdown voltage of 2250V. In addition, the E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> + E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> for the proposed structure can be reduced by 47% more than that of the conventional one, maintaining a low V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CE(sat)</sub> of 2.3V at 125°C.

A porous-core photonic crystal fiber based on a cyclic olefin homopolymer (Zeonex) is proposed; it shows high birefringence, high core power fraction, low losses, and near-zero flat dispersion. The fiber’s core was designed with quad-elliptical (QE) air holes with its center occupied by bulk background material. The superiority of the QE design over the commonly adopted tri- and penta-elliptical (TE and PE) core designs is demonstrated. The presence of the bulk material at the core center and the geometrical configuration cause a broad contrast in phase refractive indices, thereby producing high birefringence and low transmission losses. A high birefringence of 0.096 was obtained at 1.2 THz, corresponding to a total loss of 0.027 cm−1 and core power fraction of approximately 51%. The chromatic dispersion and effective area of the reported fiber were also characterized within a frequency range of 0.4–1.6 THz. The QE air holes were then filled with chemical warfare agents, namely, tabun and sarin liquids. Then, the relative sensitivity, confinement loss, fractional power flow, and effective material loss (EML) of the sensor were calculated. Nearly the same relative sensitivity (r = 64%) was obtained when the QE core was filled with either liquid. Although the obtained EML for tabun was 0.033 cm−1 and that for sarin was 0.028 cm−1, the confinement loss of the fiber when it was immersed in either liquid was negligible. The proposed fiber can be fabricated using existing fabrication technologies. Moreover, it can be applied and utilized as a THz radiation conveyor in a terahertz time domain spectroscopy system for remote sensing of chemical liquids in the security and defense industries.

Hollow core photonic bandgap fibres (HC-PBGFs) are emerging as contenders in the race to identify the best solution for next-generation high capacity transmission systems, owing to their low nonlinearity, ultimate-low signal latency, an ideal match to thulium-doped fibre amplifiers and to the promise to deliver ultralow loss, potentially comparable or even below the level of state-of-the-art single mode fibres. Recently, substantial progress in the development of HC-PBGFs has been reported; however, for these fibres to stand a realistic chance of competing with solid transmission fibres, the key challenges of loss reduction over a sufficiently wide transmission bandwidth, as well as the ability to produce fibres in multi-hundred kilometre lengths must be addressed. A predicted route to reduce loss is by increasing the core size, e.g. from 19-cell to 37-cell. In this work we review recent progress in the development of HC-PBGFs based on a 37-cell core geometry, including the realization of fibres with low loss, wide bandwidth, low modal crosstalk and low bending loss, which have paved the way to data transmission experiments using mode division multiplexing. We also investigate the issue of longitudinal uniformity in HC-PBGFs and report a systematic study of defects observed in these fibres - a first step towards their removal and thus towards the demonstration of multi-kilometre lengths of defect free fibres.

Optical waveguide crossings are becoming increasingly important due to the increasing complexity of optical chips. In switching matrices [1], multiwavelength add drop filters [2] and optical crossconnects [3] worst-case paths may contain more than five or even ten crossings. In fibre-matched waveguides structures as used in lithium niobate or silica-based technology, crossings with very low crosstalk and loss can be realised [4,5]. We have found that in highly integrated semiconductor devices crossings may contribute significantly to the loss and crosstalk performance. In this paper we present the results of a series of experiments for design of high-performance semiconductor waveguide crossings.

Rib waveguides are one of the most widely used optical waveguide structures in integrated photonics, primarily owing to their low propagation loss and ease of control. A unique and often highly desirable feature of the rib waveguides is that even when the overall cross-sectional dimension of the waveguide is large, single-mode conditions can still be achieved with specific structural configurations. In this work, we revisit and analyze the single-mode conditions for the rib waveguides using an insightful mode-matching method. Based on the theoretically exact single-mode condition, a set of highly accurate empirical single-mode conditions are established for silicon-on-insulator (SOI) rib waveguides with different cross-sections: a true single-mode condition, ensuring exclusive propagation of the HE11 mode, and a quasi-single-mode condition, which also allows the EH11 mode. These conditions are verified using both Si and silicon nitride waveguides in SOI platforms. The proposed single-mode condition is of great significance for achieving high-density, low loss, and highly reliable silicon photonic integrated circuits.

Nonisolated dc/dc converters are widely used in practice because of their low losses and high power density. To accommodate some high-power scenarios and modular applications, these nonisolated converters are usually connected in the input-parallel output-parallel (IPOP) structure. Because there is no galvanic isolation, the ac side and dc side are coupled together, which causes complicated circulating currents in the system. The great circulating currents will endanger the stable and reliable operation of the IPOP nonisolated dc/dc converters system. Focusing on this problem, this paper proposes a novel decentralized circulating currents suppression strategy for IPOP nonisolated dc/dc converters based on the modified topologies, which can still hold the main advantages of nonisolated solutions. First, the complicated circulating currents among the IPOP nonisolated dc/dc converters are analyzed in detail. It is found that various circulating currents exist in the system including the circulating currents within the single converter and the circulating currents among the multiple converters. Then, the limitations of the conventional dc/dc converter topologies are presented and it is proved that these topologies cannot eliminate all the circulating currents. Second, being inspired by the drawbacks of the conventional topologies, the modified topologies with two degrees of freedom modulation are designed. Based on the modified topologies, a corresponding suppression method consisting of two degrees of freedom control is proposed, which can eliminate the different types of circulating currents in a decoupling way. The first degree of freedom control mainly suppresses the circulating currents within the single converter, whereas the droop-based second degree of freedom control mainly suppresses the circulating currents among the multiple converters. Through the proposed solution, the IPOP nonisolated dc/dc converters can operate well with high reliability and scalability. The effectiveness of the proposed solution is validated by the real-time hardware-in-loop tests.

We develop and demonstrate a non-duplicate polarization-diversity tunable bandpass optical filter by leveraging the bi-directional transmission of add-drop dual-coupled microring resonators (MRRs) on a multi-layer Si3N4-on-silicon-on-insulator (SOI) platform. By using Euler-bends, we implement compact and low-loss Si3N4 MRRs with an equivalent bending radius of ∼38 µm. Fiber-to-fiber (on-chip) insertion loss of 4.3 dB (1.7 dB) with a low polarization-dependent loss of <0.5 dB and low differential group delay of <2.5 ps is achieved. The extinction ratio is more than 30 dB. The thermo-optic tuning efficiency of the Si3N4 MRRs is improved with a suspended micro-heater design. As a result, a wavelength tuning range of ∼2 nm and a 3-dB bandwidth tuning range of 20 GHz are experimentally demonstrated. The tuning efficiency is 33 pm/mW, which is ∼7.5 times higher than the previous design. This reconfigurable polarization-insensitive filter, with low loss, low cross talk, and high power efficiency, is highly promising for practical applications in optical communication and signal processing.

Design and performance information is presented for a divider/combiner which is to be used in an S-band solid state radar transmitter. In this application the ability to continue operation in the event of failure of one or more of the amplifier modules feeding the combiner is essential; such graceful degradation has been demonstrated. Novel features of the design are the use of a continuous annular balun launching section and the absence of internal resistors or higher-order mode suppressors. A four section impedance transformation provides a very low VSWR throughout the 2.7 to 3.1GHz radar band. The absence of internal resistors results in extremely low insertion loss, high power handling capability and high reliability. Manufacturing costs are kept low by virtue of a simple construction using few component parts.