Heinrich Hertz Institute Research Articles

Formation of Titanium Nitride, Titanium Carbide, and Silicon Carbide Surfaces by High Power Femtosecond Laser Treatment.

Invited for this month's cover is the group of Prof. Eike G. Hübner at Fraunhofer Heinrich Hertz Institute HHI, Goslar and Clausthal University of Technology, Clausthal-Zellerfeld, Germany. The cover picture shows a titanium plate, on which the crystal structure (golden circle=Ti, blue circle=O/N/C) of isomorphous TiO, TiN or TiC, respectively, has been engraved by a high-power high pulse repetition rate femtosecond laser process. The process allows for a fast and spatially resolved surface transformation of titanium to golden TiN, blue TiO/TiO2 or black TiC in an atmosphere of nitrogen, air or ethene/argon. The background represents a typical surface microstructure of these interstitial compounds obtained during this transformation. Read the full text of the article at 10.1002/cplu.202100118.

Lessons Learned During One year of Commercial Volumetric Video Production

In June 2018, Fraunhofer Heinrich Hertz Institute (HHI) together with Studio Babelsberg, ARRI, Universum Film AG (UFA), and Interlake founded the joint venture Volucap GmbH and opened a commercial volumetric video studio on the film campus of Potsdam-Babelsberg. After a testing phase, commercial productions went live in November 2018. The core technology for volumetric video production is 3D human body reconstruction (3DHBR), developed by Fraunhofer HHI. This technology captures real persons with our novel volumetric capture system and creates naturally moving dynamic 3D models, which can then be observed from arbitrary viewpoints in a virtual or augmented environment. Thanks to the large number of test productions and new requirements from customers, several lessons have been learned during the first year of commercial activity. The processing workflow for capture and production of volumetric video has been continuously evolved such as process-dependent color grading and a new encoding scheme for volumetric video. Furthermore, specific challenges have been tackled, for instance, fast movements and relighting of actors .

Advanced Volumetric Capture and Processing

Volumetric video is regarded worldwide as the next important development in media production, especially in the context of rapidly evolving virtual and augmented reality markets where volumetric video is becoming a key technology. Fraunhofer Heinrich Hertz Institute (HHI) has developed a novel technology for volumetric video. The 3D Human Body Reconstruction (3DHBR) technology captures real persons with our novel volumetric capture system and creates naturally moving dynamic 3D models, which can then be observed from arbitrary viewpoints in a virtual or augmented reality scene. The capture system consists of an integrated multicamera and lighting system for a full 360° acquisition. A cylindrical studio has been developed with a diameter of 6 m and consists of 32 20-MPixel cameras and 120 light-emitting-diode (LED) panels that allow for an arbitrary lit background. Hence, diffuse lighting and automatic keying are supported. The avoidance of green screen and provision of diffuse lighting offers the best possible conditions for relighting of the dynamic 3D models afterward at the design stage of the virtual reality (VR) experience. In contrast to classical character animation, facial expressions and moving clothes are reconstructed at high geometrical detail and texture quality. The complete workflow is fully automatic, requires about 12 hr/min of mesh sequence, and provides a high level of quality for immediate integration in virtual scenes. Meanwhile, a second, professional studio has been built up on the film campus of Potsdam Babelsberg. This studio is operated by VoluCap GmbH, a joint venture between Studio Babelsberg, ARRI, UFA, Interlake, and Fraunhofer Heinrich Hertz Institute (HHI).

InP AAC for data compression applications

The authors propose a 2 × 2 asymmetric adiabatic coupler (AAC) indium phosphide (InP) photonic integrated circuit (PIC), suitable for tunable power applications such as all-optical data processing. The device was idealised as the key building block in Haar transform network used for image compression, allowing to perform the necessary separate addition and subtraction of incoming input signals at its output ports. The tunable behaviour of the coupler was demonstrated experimentally for addition/subtraction and splitting (with experimental coupling ratios of 77:23/14:86 and 50:50, respectively) through phase control. The use of the developed InP PIC enables a low footprint structure design together with the high-quality active components (lasers, photodetectors and phase modulators) of Fraunhofer Gesellschaft Heinrich Hertz Institute design toolkit. The proposed study provides a full experimental characterisation of the AAC, exploring its tuning properties and enabling further usage in a plethora of applications in high processing computing and data communications.

Psychoacoustics in Germany in the period 1900 to 1950

Psychoacoustic research in Germany in this period was performed in the context of various academic disciplines (experimal psychology, musicology, physics, communication engineering) and a range of institutions, covering both industrial laboratories (AES, Siemens & Halske), (technical) universities (Berlin, Breslau, Dresden) and (semi) governmental institutions like the Heinrich-Hertz Institut für Schwingungsforschung (Oscillation Research) and imperial mail research institutions. Prominent researchers were Heinrich Barkhausen (appointed as professor at the TU Dresden in 1911 for the field communications engineering); Erwin Waetzman (since 1912 professor at the University Breslau); Ferdinand Trendelenburg (since 1922 with Siemans & Halske, Berlin, in addition since 1935 adjunct professor at the University Berlin); Erwin Meyer, since 1928 at the Heinrich-Herz Institute in Berlin. The research questions were often derived from technical needs of the upcoming communication and radio industry, or addressed consequences of innovations like the car. Barkhausen introduced in 1926 a loudness meter (by comparison with a standardized reference), which was taken into production by Siemens a year later. Waetzmann’s habilitation thesis (1907, published as book in 1912) extended Helmholtz’ studies on the damping characteristics of “ear resonators.” Erwin Meyer started with binaural research in 1924 because he recognized its relevance for stereophonic sound reproduction.

Recent Developments in Polymer-Based Photonic Components for Disruptive Capacity Upgrade in Data Centers

Recently developed photonic components for next-generation datacenter systems based on the Heinrich Hertz Institute´s PolyBoard integration platform are reviewed. Hybrid-integrated transmitters and receivers, including optical functionalities, such as tunable lasers, polarization manipulators, 1 × 2 switches, and variable optical attenuators, are presented. The flexibility of those devices provides the possibility of generating, routing and detecting multiple optical data flows, offering the potential of aggregating traffics of 1 Tb/s and beyond. In addition, vertically stacked polymer waveguide structures are presented, opening the way towards the third dimension in photonic integration and allowing increasing the transmission capacity beyond the physical limit of standard single mode fibers. The freedom in the arrangement of the polymer waveguides allow for the matching of different multicore fiber types, providing the possibility of processing in parallel the different optical flows. By means of micromachining 45 $^{\circ}$ mirrors on the different stack levels, the three-dimensional (3-D) stacked waveguide structure can act as an interface between multicore fibers and planar optoelectronic devices such as photodiodes and laser diodes. Furthermore, a novel concept for a 4 × 4 3-D optical switch based on 3-D multimode interferometers is presented and numerically proven, showing potential for its application as the interface between multicore fibers and planar optoelectronic devices, as well as offering the possibility of reconfigurable N × N switching matrices.

Enabling Technologies for Fifth-Generation Mobile Communications

1Beijing University of Posts and Telecommunications, Beijing 100876, China 2China Mobile Research Institute, Beijing 100053, China 3Samsung Electronics Co., Ltd., Suwon-si, Gyeonggi-do 443-742, Republic of Korea 4Fraunhofer Heinrich Hertz Institute, 10587 Berlin, Germany 5Qualcomm Inc., 5775 Morehouse Drive, San Diego, CA 92121, USA 6Department of Electrical and Computer Engineering, University of California at San Diego, San Diego, CA 92093, USA

Open access to technology platforms for InP-based photonic integrated circuits

Abstract Open access to generic technology platforms for photonic integrated circuit manufacturing enables low-cost development of application-specific photonic chips for novel or improved products. It brings photonic ICs within reach for many industrial users and research institutes, by moving toward a fabless business model. In the current status, InP-based open access manufacturing services are offered through multi-project wafer runs by Fraunhofer Heinrich Hertz Institut, SMART Photonics, and Oclaro. In this paper, we review state-of-the-art InP photonic integration technology platforms, present examples of complex InP photonic ICs developed in the generic technologies, and give a prospect for further development of these photonic integration platforms.

Divergence-based Spatial Filtering for robust BCI

Event Abstract Back to Event Divergence-based Spatial Filtering for robust BCI Wojciech Samek1* 1 Fraunhofer Heinrich Hertz Institute, Video Coding & Analytics, Germany Despite significant technological advances over the last years, Brain-Computer Interfacing (BCI) are still scarcely used outside laboratories. One reason preventing the prevalence of this promising technology into everyday life of, e.g., patients, is the lack of robustness and reliability. Noise, artifacts and nonstationarity are intrinsic parts of the recorded brain signal and can severely corrupt the BCI decoding process. Recently, a new generation of BCI spatial filtering algorithms based on robust divergences [1-4] have been proposed to tackle the robustness problem. These methods project the EEG signal to a discriminative, low-dimensional subspace by maximizing a divergence-based objective. In this subspace different BCI-related mental states (e.g., left / right hand motor imagination) are better separable, because the ERD/ERS effect is enhanced. Due to the intrinsic robustness of beta or gamma divergence the spatial filter computation is less affected by noise and artifacts than when using the popular Common Spatial Patterns (CSP) method. Acknowledgements This work was supported in part by the Federal Ministry of Education and Research (BMBF) under the project Adaptive BCI (FKZ 01GQ1115).

An interview with Aljosa Smolic

Dr. Aljosa Smolic joined Disney Research Zürich, Switzerland in 2009, as Senior Research Scientist and Head of the "Advanced Video Technology" group. Before he was Scientific Project Manager at the Fraunhofer Institute for Telecommunications, Heinrich- Hertz-Institut (HHI), Berlin, also heading a research group. He has been involved in several national and international research projects, where he conducted research in various fields of video processing, video coding, computer vision and computer graphics and published more than 100 refereed papers in these fields. In current projects he is responsible for research in 2D video, 3D video and free viewpoint video processing and coding.

A new phase for THz

A team from the Heinrich Hertz Institut (HHI) have created a wavelength selective phase modulation (WSPM) technique that allows the usual mechanical delay stages in a CW THz spectrometer to be replaced with complete fibre-coupled electro-optical phase modulators. The resulting THz spectrometer is compact, has no mechanical wear and is able to modulate the THz phase with high speed up to the GHz range.“The challenge was to find a concept for a wavelength selective phase modulation scheme in combination with a subsequent beat signal generation,” said Dennis Stanze, a researcher at HHI. “With our concept, CW THz spectrometers become fast without any drawback in stability and have more functionality than conventional CW THz spectrometers. That will bring CW THz systems from a lab technique with potential applications to real world use.”

Tools and Products

Department editor Dave Kasik highlights some of the new computer graphics tools and products on the market. In this issue the featured tools and products are a 3D visualization system from iZ3D, a virtual-camera tracking system from Intersense, a virtual mirror camera from Heinrich-Hertz Institute, a GPU-based ray tracer from Nvidia, an enhanced keyboard rollerbar from Contour Design, a digital-image enhancer from Akvis Software, and a visual search tool from LeafThrough.

Are niche markets Europe's last chance in semiconductors?

Last year the Heinrich Hertz Institute in Berlin completed the development of an electronic video projection system with a fully fledged laboratory demonstrator. It works very much like the celluloid film in an ordinary movie projector – albeit by reflecting rather than transmitting light – and does not have any moving parts. The prototype is based on a sophisticated “light-valve chip” that electronically controls the pixels of a viscoelastic silicon-gel film and incorporates all the features needed for projecting digital high-definition TV (HDTV).

BERKOM: The first broadband isdn exchange and transmission system in Berlin

BERKOM: The first broadband isdn exchange and transmission system in Berlin

3D TV projection

Work being carried out at the Heinrich-Hertz Institut in Berlin could lead to the development of large-screen three-dimensional TV

Eastern thunderstorms located by VLF atmospherics parameters

Daily variations of spectral atmospherics parameters, as measured by the atmospheric analyzer of the Heinrich Hertz Institut in Berlin‐Charlottenburg, are analyzed over an eight day period for long lasting storm centers within the octant NE‐E (receiving station Stockert near Bonn). The delay‐time difference and the amplitude ratio of spectral groups at 6 and 8 kHz were measured alternatively every 5 min. Within the first‐mode approximation these parameters are proportional to the propagation distance. Storm centers located by these parameter measurements are compared with synoptical observations. As theory indicates, the strong directional dependence of the GDD (group delay‐time difference) and the SAR (spectral amplitude ratio) on the propagation direction relative to the earth's magnetic field is verified by these measurements.

A New Feature of the Spectrum of the s-Component of Solar Radio Emission

IN the present minimum of solar activity, investigations of the spectrum of the quiet Sun in the cm- and dm-regions as well as the spectrum of single centres of the slowly varying component (s-component) of solar radio emission are of particular interest. Absolute calibrations of radio telescopes carried out at the Heinrich Hertz Institute, Berlin-Adlershof (HHI), led during recent years to spectra of the quiet Sun flux density and of the s-component which are somewhat different from earlier assumed spectra.

Apparent Relation between Solar Activity and the 440-Mc/s Radar Distance of Venus

A CURIOUS correlation (Fig. 1) has been found between the systematic variations in the astronomical unit, as derived from radar observations of Venus at 440 Mc/s (68 cm)1, and the solar 20-cm flux as measured at the Heinrich Hertz Institut in Berlin-Adlers-hof2. The 20-cm flux is known to be a good indicator of solar activity, and there is evidence that solar decimetre radiation (slowly varying component) is related to both the solar extreme ultra-violet flux and the solar wind intensity3,4.

Radio Research Laboratories Abroad

THE rapid and widespread growth of radio communication and its associated industries has been one of the most notable events during the past fifteen years. The inception and development of broadcasting, and later of television, resulting from the earlier introduction of the thermionic valve to industry, have revolutionised the scope of normal commercial telegraphic and telephonic communication. These developments have naturally been accompanied by the establishment of radio frequency research laboratories in all parts of the world, some of these being controlled by government administration, while others are associated with private enterprise. The issue of La Nature of September 15 is devoted to an illustrated account of several such radio research laboratories. Much space is devoted to the work of the French institutions, Le Laboratoire National de Radio-Electricite, Le Laboratoire du Comite Consultatif, Les Laboratoires de Recherches du “Materiel Téléphonique”, and to the private laboratories engaged on television. In addition, however, the work of the Heinrich Hertz Institute and of M. von Ardenne in Berlin are described briefly ; while attention is also devoted to the Philips Laboratories at Eindhoven, the Bell Telephone Laboratories in New York, the Italian Television Laboratory and that of the Baird Television Laboratory, the only English laboratory mentioned. Further articles deal with work in France in connexion with broadcasting, valve manufacture and research on the interference problem. The whole issue presents an interesting summary of the scope and position of research in the institutions enumerated.

Scientific Studies of Noise

THE subject of noise control is being actively studied scientifically at the U.S. Bureau of Standards, the Heinrich Hertz Institute in Berlin, and at the National Physical Laboratory in Great Britain, while a number of firms have developed noise-measuring apparatus, means for reducing noise-levels, and materials and methods for isolating vibration. Literature tells us that the noise problem is by no means new, but in addition to the old sources of noise, civilisation brings in new sources; there is evidence of a growing noise-consciousness in the Summary of an address delivered by Dr. G. W. C. Kaye, superintendent of the Physics Department, National Physical Laboratory, before the Science and Noise Section of the Conference of the Anti-Noise League held at Oxford on July 14.