From The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH): “Photonics chip allows light amplification”

From The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH)

12.1.22
Johann Riemensberger
Nik Papageorgiou

The photonic integrated circuits used in this study. Credit: Tobias Kippenberg (EPFL)

Scientists at EPFL have developed photonic integrated circuits that demonstrated a new principle of light amplification on a silicon chip. It can be employed for optical signals like those used in Lidar, trans-oceanic fiber amplifiers or in data center telecommunications.

The ability to achieve quantum-limited amplification of optical signals contained in optical fibers is arguably among the most important technological advances that are underlying our modern information society. In optical telecommunications, the choice of 1550 nm wavelength band is motivated not only by loss minima of silica optical fibers (a development recognized with the 2008 Nobel Prize in Physics), but equally to the existence of ways to amplify these signals, crucial to achieve trans-oceanic fiber optical communication.

Optical amplification plays a key role in virtually all laser-based technologies such as optical communication, used for instance in data-centers to communicate between servers and between continents through trans-oceanic fiber links, to ranging applications like coherent Frequency Modulated Continuous Wave (FMCW) LiDAR – an emerging technology that can detect and track objects farther, faster, and with greater precision than ever before. Today, optical amplifiers based on rare-earth ions like erbium, as well as III-V semiconductors, are widely used in real-world applications.

These two approaches are based on amplification by optical transitions. But there is another paradigm of optical signal amplification: traveling-wave parametric amplifiers, which achieve signal amplification by varying a small system “parameter”, such as the capacitance or the nonlinearity of a transmission line.

Optical parametric amplifiers

It has been known since the 80’s that the intrinsic nonlinearity of optical fibers can also be harnessed to create traveling-wave optical parametric amplifiers, whose gain is independent of atomic or semiconductor transitions, which means that it can be broad-band and virtually cover any wavelength.

Parametric amplifiers also do not suffer from a minimum input signal, which means that they can be used to amplify both the faintest signals and large input power in a single setting. And finally, the gain spectrum can be tailored by waveguide geometry optimization and dispersion engineering, which offers enormous design flexibility for target wavelengths and applications.

Most intriguingly, parametric gain can be derived in unusual wavelength bands that are out of reach of conventional semiconductors or rare-earth-doped fibers. Parametric amplification is inherently quantum-limited, and can even achieve noiseless amplification.

Silicon limitations

Despite their attractive features, optical parametric amplifiers in fibers are compounded by their very high pump power requirements resulting from the weak Kerr nonlinearity of silica. Over the past two decades, the advances in integrated photonic platforms have enabled significantly enhanced effective Kerr nonlinearity that cannot be achieved in silica fibers, but have not achieved continuous-wave-operated amplifiers.

“Operating in the continuous-wave regime is not a mere ‘academic achievement’,” says Professor Tobias Kippenberg, head of EPFL’s Laboratory of Photonics and Quantum Measurements at EPFL. “In fact, it is crucial to the practical operation of any amplifier, as it implies that any input signals can be amplified – for example, optically encoded information, signals from LiDAR, sensors, etc. Time- and spectrum-continuous, travelling-wave amplification is pivotal for successful implementation of amplifier technologies in modern optical communication systems and emerging applications for optical sensing and ranging.”

Breakthrough photonic chip

A new study [Nature (below)] led by Dr Johann Riemensberger in Kippenberg’s group has now addressed the challenge by developing a traveling-wave amplifier based on a photonic integrated circuit operating in the continuous regime. “Our results are a culmination of more than a decade of research effort in integrated nonlinear photonics and the pursuit of ever lower waveguide losses,” says Riemensberger.

The researchers used an ultralow-loss silicon nitride photonic integrated circuit more than two meters long to build the first traveling-wave amplifier on a photonic chip 3×5 mm2 in size. The chip operates in the continuous regime and provides 7 dB net gain on-chip and 2 dB net gain fiber-to-fiber in the telecommunication bands. On-chip net-gain parametric amplification in silicon nitride was also recently achieved by the groups of Victor Torres-Company and Peter Andrekson at Chalmers University.

In the future, the team can use precise lithographic control to optimize the waveguide dispersion for parametric gain bandwidth of more than 200 nm. And since the fundamental absorption loss of silicon nitride is very low (around 0.15 dB/meter), further fabrication optimizations can push the chip’s maximum parametric gain beyond 70 dB with only 750 mW of pump power, exceeding the performance of the best fiber-based amplifiers.

“The application areas of such amplifiers are unlimited,” says Kippenberg. “From optical communications where one could extend signals beyond the typical telecommunication bands, to mid-infrared or visible laser and signal amplification, to LiDAR or other applications where lasers are used to probe, sense and interrogate classical or quantum signals.”

Science paper:
Nature

See the full article here .

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EPFL campus

The Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH) is a research institute and university in Lausanne, Switzerland, that specializes in natural sciences and engineering. It is one of the two Swiss Federal Institutes of Technology, and it has three main missions: education, research and technology transfer.

The QS World University Rankings ranks EPFL(CH) 14th in the world across all fields in their 2020/2021 ranking, whereas Times Higher Education World University Rankings ranks EPFL(CH) as the world’s 19th best school for Engineering and Technology in 2020.

EPFL(CH) is located in the French-speaking part of Switzerland; the sister institution in the German-speaking part of Switzerland is The Swiss Federal Institute of Technology ETH Zürich [Eidgenössische Technische Hochschule Zürich] (CH). Associated with several specialized research institutes, the two universities form The Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles Polytechniques Fédérales] (CH) which is directly dependent on the Federal Department of Economic Affairs, Education and Research. In connection with research and teaching activities, EPFL(CH) operates a nuclear reactor CROCUS; a Tokamak Fusion reactor; a Blue Gene/Q Supercomputer; and P3 bio-hazard facilities.

ETH Zürich, EPFL (Swiss Federal Institute of Technology in Lausanne) [École Polytechnique Fédérale de Lausanne](CH), and four associated research institutes form The Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles polytechniques fédérales] (CH) with the aim of collaborating on scientific projects.

The roots of modern-day EPFL(CH) can be traced back to the foundation of a private school under the name École Spéciale de Lausanne in 1853 at the initiative of Lois Rivier, a graduate of the École Centrale Paris (FR) and John Gay the then professor and rector of the Académie de Lausanne. At its inception it had only 11 students and the offices were located at Rue du Valentin in Lausanne. In 1869, it became the technical department of the public Académie de Lausanne. When the Académie was reorganized and acquired the status of a university in 1890, the technical faculty changed its name to École d’Ingénieurs de l’Université de Lausanne. In 1946, it was renamed the École polytechnique de l’Université de Lausanne (EPUL). In 1969, the EPUL was separated from the rest of the University of Lausanne and became a federal institute under its current name. EPFL(CH), like ETH Zürich (CH), is thus directly controlled by the Swiss federal government. In contrast, all other universities in Switzerland are controlled by their respective cantonal governments. Following the nomination of Patrick Aebischer as president in 2000, EPFL(CH) has started to develop into the field of life sciences. It absorbed the Swiss Institute for Experimental Cancer Research (ISREC) in 2008.

In 1946, there were 360 students. In 1969, EPFL(CH) had 1,400 students and 55 professors. In the past two decades the university has grown rapidly and as of 2012 roughly 14,000 people study or work on campus, about 9,300 of these being Bachelor, Master or PhD students. The environment at modern day EPFL(CH) is highly international with the school attracting students and researchers from all over the world. More than 125 countries are represented on the campus and the university has two official languages, French and English.

Organization

EPFL is organized into eight schools, themselves formed of institutes that group research units (laboratories or chairs) around common themes:

School of Basic Sciences
Institute of Mathematics
Institute of Chemical Sciences and Engineering
Institute of Physics
European Centre of Atomic and Molecular Computations
Bernoulli Center
Biomedical Imaging Research Center
Interdisciplinary Center for Electron Microscopy
MPG-EPFL Centre for Molecular Nanosciences and Technology
Swiss Plasma Center
Laboratory of Astrophysics

School of Engineering

Institute of Electrical Engineering
Institute of Mechanical Engineering
Institute of Materials
Institute of Microengineering
Institute of Bioengineering

School of Architecture, Civil and Environmental Engineering

Institute of Architecture
Civil Engineering Institute
Institute of Urban and Regional Sciences
Environmental Engineering Institute

School of Computer and Communication Sciences

Algorithms & Theoretical Computer Science
Artificial Intelligence & Machine Learning
Computational Biology
Computer Architecture & Integrated Systems
Data Management & Information Retrieval
Graphics & Vision
Human-Computer Interaction
Information & Communication Theory
Networking
Programming Languages & Formal Methods
Security & Cryptography
Signal & Image Processing
Systems

School of Life Sciences

Bachelor-Master Teaching Section in Life Sciences and Technologies
Brain Mind Institute
Institute of Bioengineering
Swiss Institute for Experimental Cancer Research
Global Health Institute
Ten Technology Platforms & Core Facilities (PTECH)
Center for Phenogenomics
NCCR Synaptic Bases of Mental Diseases

College of Management of Technology

Swiss Finance Institute at EPFL
Section of Management of Technology and Entrepreneurship
Institute of Technology and Public Policy
Institute of Management of Technology and Entrepreneurship
Section of Financial Engineering

College of Humanities

Human and social sciences teaching program

EPFL Middle East

Section of Energy Management and Sustainability

In addition to the eight schools there are seven closely related institutions

Swiss Cancer Centre
Center for Biomedical Imaging (CIBM)
Centre for Advanced Modelling Science (CADMOS)
École Cantonale d’art de Lausanne (ECAL)
Campus Biotech
Wyss Center for Bio- and Neuro-engineering
Swiss National Supercomputing Centre

From Geospatial World: “Israeli scientists develop world’s first formation flying nano satellites and England to be mapped with 3D LiDAR and more”

Geospatial World

2.2.18
No writer credit found

Israeli scientists develop world’s first formation flying nano satellites.

Venus, the Israeli minisatellite. Image Courtesy: Israeli Space Agency
A cluster of three nano-satellites developed by scientists at Technion-Israel Institute of Technology, Haifa, will be the world’s first to be flown in formation.

The project, developed with the collaboration of the French Adelis-Samson Foundation and the Israeli Space Agency (ISA), will be launched on the Indian launcher PSLV at the end of 2018 by the Dutch company Innovative Solutions In Space, which has a specialization in launching Nano-satellites.

The project has been developed by a team of researchers lead by Prof. Pini Gurfil, who is the head of the Asher Institute for Space Research and a member of the aerospace engineering faculty at the Technion. It has been designed to demonstrate that a combination of satellites can hold together in a controlled formation for a year some 600 kilometers above Earth.

“Israeli technology is breaking boundaries and proving its innovation again and again,” said Science and Technology Minister Ofir Akunis to The Jerusalem Post. “We are proud to be part of this flagship project, which is a significant contribution to the advancement of space in Israel and to the training of students in the field.”

The satellites will be used to receive signals from Earth and compute the precise location of the source of the broadcast for rescue, detection, remote sensing and environmental monitoring.

Each of the satellites is 10 cm. x 20 cm. x 30 cm. – approximately the size of a shoebox – and weighs about eight kg. They will be equipped with measuring devices, antennas, computer and control systems and navigation devices.

The software and algorithms that will control the flight were developed in a laboratory for distributed space systems at the Technion.

“Miniaturization in the field of satellites, together with advanced Israeli technology, allows us to take Israel an important step forward with mini-satellites,” added Gurfil. “The degree of innovation of nano-satellites can be compared to switching from a PC to a mobile phone, which offers far more capabilities than its predecessors.”

“The field of nanosciences has been increasing significantly in recent years and the number of launches doubles every year,” said Israeli Space Agency director Avi Blasberger. “The development and launch costs of such satellites, capable of filling a variety of uses, are significantly lower than those of conventional satellites… In the near future, networks are expected to include thousands of nano-satellites that will cover the Earth and enable high-speed Internet communications at a significantly lower cost than today.”

England to be mapped with 3D LiDAR scanners to tackle flooding

Planning to tackle flooding, and track illegal waste dumps in England, LiDAR mapping will be conducted in all of England, announced Environment Agency. Aircraft equipped with laser scanners will map all 130,000 square kilometers (50,000 square miles) of the country in 3D, including rivers, fields and national parks, by 2020.

Lidar (also called LIDAR, LiDAR, and LADAR) is a surveying method that measures distance to a target by illuminating that target with a pulsed laser light, and measuring the reflected pulses with a sensor. Differences in laser return times and wavelengths can then be used to make digital 3D-representations of the target. The name lidar, sometimes considered an acronym of Light Detection And Ranging[1] (sometimes Light Imaging, Detection, And Ranging), was originally a portmanteau of light and radar.[2][3]

Lidar is commonly used to make high-resolution maps, with applications in geodesy, geomatics, archaeology, geography, geology, geomorphology, seismology, forestry, atmospheric physics,[4] laser guidance, airborne laser swath mapping (ALSM), and laser altimetry. The technology is also used for control and navigation for some autonomous cars. Lidar sometimes is called laser scanning and 3D scanning, with terrestrial, airborne, and mobile applications.

The data gathered will be used to understand flooding risk and plan flood defenses, and will also be made available for free for the public and industry including archaeologists, urban planners and even gamers. Around 75% of the country is already mapped, but there is only sporadic coverage of upland areas and the new project, beginning over winter, will fill in the gaps.

The new data will be better quality than ever before, the Environment Agency said, with the whole country mapped at a one meter resolution using the most up-to-date laser technology to reveal the terrain more clearly. The LiDAR will be used to detect sudden landscape changes which could indicate illegal tips.

Other government agencies can use it to help improve the environment. For example, Natural England assesses wildlife habitat while the Forestry Commission can learn more about tree cover. And it can reveal hidden secrets of the country’s past, with archaeologists using it to uncover lost Roman roads in northern England.

Environment Agency chief executive Sir James Bevan said: “This ambitious project will enhance our understanding of England’s unique natural features and landscape, helping us to better understand flood risk, plan effective defenses and fight waste crime.

“I’m pleased we are able to gather, use and share such valuable data to contribute to environmental improvements and conservation. It’s just one of the many ways the Environment Agency is using technology to help people and wildlife.”

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From U Washington: “Technology to improve rockfall analysis on cliffs could save money, lives”

University of Washington

April 11, 2017
Jennifer Langston

This LiDAR image of a rock slope on Alaska’s Glenn Highway shows the “kinetic energy” of the slope, with red indicating a higher hazard from rockfalls.Matthew O’Banion/Oregon State University

Pacific Northwest engineers have developed a new, automated technology to analyze the potential for rockfalls from cliffs onto roads and areas below, which should speed and improve this type of risk evaluation, help protect public safety and ultimately save money and lives.

Called a “rockfall activity index,” the system is based on the powerful abilities of light detection and ranging, or LIDAR technology. It should expedite and add precision to what’s now a somewhat subjective, time-consuming process to determine just how dangerous a cliff is to the people, vehicles, roads or structures below it.

This is a multimillion-dollar global problem, experts say, of significant concern to transportation planners.

It’s a particular concern in the Pacific Northwest with its many mountain ranges, heavy precipitation, erosion of steep cliffs and unstable slopes, and thousands of roads that thread their way through that terrain. The evaluation system now most widely used around the world, in fact, was developed by the Oregon Department of Transportation more than 25 years ago.

The new technology should improve on that approach, according to researchers who developed it from the University of Washington, Oregon State University and the University of Alaska Fairbanks. Findings were just published in Engineering Geology.

“Transportation agencies and infrastructure providers are increasingly seeking ways to improve the reliability and safety of their systems, while at the same time reducing costs,” said Joe Wartman, associate professor of civil and environmental engineering at the University of Washington, and corresponding author of the study.

“As a low-cost, high-resolution landslide hazard assessment system, our rockfall activity index methodology makes a significant step toward improving both protection and efficiency.”

The new approach could replace the need to personally analyze small portions of a cliff at a time, looking for cracks and hazards, with analysts sometimes even rappelling down it to assess risks. LIDAR analysis can map large areas in a short period, and allow data to be analyzed by a computer.

“Rockfalls are a huge road maintenance issue,” said co-author Michael Olsen, an associate professor of geomatics at Oregon State University.

“Pacific Northwest and Alaskan highways, in particular, are facing serious concerns for these hazards. A lot of our highways in mountainous regions were built in the 1950s and 60s, and the cliffs above them have been facing decades of erosion that in many places cause at least small rockfalls almost daily. At the same time traffic is getting heavier, along with increasing danger to the public and even people who monitor the problem.”

The study, based on some examples in southern Alaska, showed the new system could evaluate rockfalls in ways that very closely matched the dangers actually experienced. It produces data on the “energy release” to be expected from a given cliff, per year, that can be used to identify the cliffs and roads at highest risk and prioritize available mitigation budgets to most cost-effectively protect public safety.

Tens of millions of dollars are spent each year in the U.S. on rock slope maintenance and mitigation.

“This should improve and speed assessments, reduce the risks to people doing them, and hopefully identify the most serious problems before we have a catastrophic failure,” Olsen said.

The technology is now complete and ready for use, researchers said, although they are continuing to develop its potential, possibly with the use of flying drones to expand the data that can be obtained.

This research was supported by the UW-based Pacific Northwest Transportation Consortium, the National Science Foundation and the Alaska Department of Transportation and Public Facilities. Co-authors are Lisa Dunham, a UW graduate in civil and environmental engineering now at McMillen Jacobs Associates in Seattle; graduate assistant Matthew O’Banion at OSU; and Keith Cunningham, research assistant professor of remote sensing at the University of Alaska Fairbanks.

For more information, contact Joe Wartman at wartman@uw.edu or 206-685-4806.

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