Tag Archives: Semiconductors

Photonics Meets Plasmonics in New Switch that Could Steer Lidar Laser Beams

Post Syndicated from Jeff Hecht original https://spectrum.ieee.org/tech-talk/semiconductors/optoelectronics/new-electro-mechanical-switch-integrated-photonics

The synergy of electronic processing and optical communications has powered the decades-long boom in information technology. But the need to convert signals back and forth between electrical and optical forms is becoming a bottleneck for the emerging field of integrated photonics.

A new type of switch that combines electrical and mechanical effects to redirect light could open the door to large-scale reconfigurable photonic networks for several applications including beam steering for lidars and optical neural networks for computing. 

Currently, integrated photonics are used in high-performance fiber-optic systems , and a joint government-industry program called AIM Photonics is pushing their manufacture. However, current optical switches are too big and require too much power to blend well into integrated photonics. The new hybrid nano-opto-electro-mechanical switch has a footprint of 10 square micrometers and runs on only one volt—making it compatible with the CMOS (complementary metal-oxide-semiconductor) silicon electronics used in integrated photonics, says Christian Haffner from the Swiss Federal Institute of Technology in Zurich now working at the National Institute for Standards and Technology (NIST) in Gaithersburg, Maryland and the researcher who led the team that developed it.

The root of the problem Haffner set out to solve is that photons and electrons behave very differently.

Photons are great for communications because they travel at the speed of light and interact weakly with each other and matter, but they are much larger than chip features and require high voltages to redirect them because of their weak interactions.

Electrons are much smaller and interact much more strongly than photons, making them better for switching and for processing signals. However, electrons move slower than light, and more energy is needed to move them.

Long-distance communication systems process signals electronically and convert the signal into light for transmission, but converting between signal formats is cumbersome for local transmission. The new switch makes it possible to redirect optical signals on the integrated photonic circuit without having to convert them to electrical format and then back to optical format for further transmission. 

In Science, Haffner and colleagues describe a hybrid nano-opto-electro-mechanical switch that would occupy only about 10 square micrometers on an integrated photonic circuit. Their switch is a small multilayered disk sitting at a T-junction between two optical waveguides—stripes of transparent silica that guide light—that meet at a right angle. The top layer of the disk is a four-micrometer circle of 40-nanometer gold membrane resting on a small piece of alumina on layer of silicon deposited on silica. That structure acts as a curved waveguide resonant with both the input and output waveguides, so it can transfer resonant light between the two. 

Light within the silica waveguides remains as photons, but within the switch the light excites oscillations of surface electrons in the gold, producing plasmons that vibrate at the frequency of the light wave but over a light much smaller than the optical wavelength. That tight confinement of the plasmonic part of the energy in the air gap between the gold and silicon creates a strong opto-electro-mechanical effect concentrated in the small volume of the switch. 

With no voltage applied to the switch, the plasmonic waveguide remains resonant with the silica waveguides, so it couples light from the input waveguide to the output waveguide with minimal loss, as shown in the animation.

Applying one volt to the switch produces a static charge that pulls the gold membrane toward the silicon layer, changing the shape of the waveguide in the switch so it shifts the phase of the light by 180 degrees. This causes destructive interference in the switch, breaking the resonance and the coupling of light into the side waveguide, so the light instead continues through the input waveguide to another switch.

“What we have in the end,” says Haffner, “is a hybrid [switch], partly photonic and partly plasmonic, that manipulates light very efficiently.” The plasmonic part concentrates the switching in a small area; the photonic part experiences low loss. Applying a one-volt bias compatible with CMOS electronics across such a short distance can produce a very strong force. That gives the switch a small footprint, low loss, and lower power consumption, which conventional electro-optic switches cannot achieve simultaneously.

Mass of the gold film is so low that the switch can operate millions of times a second. That’s adequate for most switching, says Haffner, but it does have limits. The mechanical part of the switch cannot reach the picosecond speeds needed to modulate light in an optical transmitter. 

The first applications are likely to be in laser beam steering for lidar, particularly for autonomous vehicles where continual information on the local environment is vital for safety. Another potential application is optical routing of signals on integrated photonic chips to create optical neural networks for deep-learning applications. The switch can redirect signals millions of times a second, a time scale needed by such applications.

“I don’t see any issues in fabricating [the switches] with high yield,” says Haffner. 

How to Reduce the Bill of Material Costs with Digital Signal Processing

Post Syndicated from IEEE Spectrum Recent Content full text original https://spectrum.ieee.org/whitepaper/how-to-reduce-the-bill-of-material-costs-with-digital-signal-processing

The need to decrease the bill of material (BOM) costs in embedded products is being driven by the need for high volume, low-cost sensor systems. As IoT devices become more sophisticated, they require developers to utilize digital signal processing (DSP) to handle more features within the product, such as device provisioning.

In this paper, we will examine how DSP can be used to reduce a product’s cost.

You will learn:

  • The technology trends moving data processing to the edge of the network to enable more compute performance
  • The benefits of digital signal processing, including decreased product dimensions, product flexibility, shorter design cycle, and in-field adaptability
  • How to convert analog circuits to software using modeling software such as MathWorks MATLAB or Advanced Solutions Nederlands (ASN) filter designer
  • How to select the right DSP processor solution to benefit from reduced BOM costs
  • The capabilities and features of the Arm Cortex-M processors with DSP extensions to help you get your signal processing application running as quickly as possible

Artificial Intelligence in Software Defined SIGINT Systems

Post Syndicated from IEEE Spectrum Recent Content full text original https://spectrum.ieee.org/whitepaper/artificial-intelligence-in-software-defined-sigint-systems

As wireless protocols grow more complex, spectrum environments become more contested and electronic warfare increases in sophistication.

Read how you can combine artificial intelligence and deep learning with commercial off-the-shelf software-defined radio hardware to train algorithms.

You can teach them to detect new threats faster, reduce development risk and support burden, and deploy in signals intelligence and spectrum monitoring scenarios limited by SWaP (size, weight, and power). 

U.S. Invests in Fabs That Make Radiation-Hardened Chips

Post Syndicated from Samuel K. Moore original https://spectrum.ieee.org/tech-talk/semiconductors/devices/us-invests-in-radiationhardenedchip-fabs

The U.S. is investing in upgrades to the fabrication facility that makes the radiation-hardened chips for its nuclear arsenal. It is also spending up to US $170-million to enhance the capabilities of SkyWater Technology Foundry, in Bloomington, Minn., in part to improve the company’s radiation-hardened-chip line for other Defense Department needs.

A Simple Filter Turns Blue OLED Light Into White

Post Syndicated from XiaoZhi Lim original https://spectrum.ieee.org/tech-talk/semiconductors/optoelectronics/a-simple-filter-makes-blueemitting-oleds-give-off-white-light

Organic light-emitting diodes (OLEDs) have come a long way since the first working device was reported three decades ago. Prized for their dark blacks, crisp image reproduction, and power efficiency, today’s OLEDs dominate the screens of Android phones and LG televisions. They may take over iPhones as early as next year.

And because OLEDs are cheap and easy to make, we ought to also use them to make white light for general illumination, says Konstantinos Daskalakis, a post-doctoral researcher at Aalto University in Finland.

Except white is an OLED’s Achilles’ heel. Typically, to get white light, individual red, green, and blue emitters shine at the same time. This makes white the most power-hungry color, reportedly requiring six times as much power as it takes to produce the color black on a Google Pixel. Other strategies to generate white light include carefully doping emitting layers with chemicals, but this approach makes it harder to fabricate devices.

In a proof-of-concept experiment, Daskalakis and his supervisor Paivi Torma converted conventional blue-emitting OLEDs to white-emitting ones simply by depositing a distributed Bragg reflector (DBR)—a stack of two alternating materials with high and low refractive indexes—on top of the OLEDs.

Wanted: A Bomb Detector as Sensitive as a Dog’s Nose

Post Syndicated from Michelle Hampson original https://spectrum.ieee.org/tech-talk/semiconductors/devices/using-a-twopronged-approach-to-detect-explosive-substances-from-bombs

If a suicide bomber lurks in the public with an explosive device, bomb-sniffing dogs can often detect the explosive chemicals from the tiniest whiff—these canine superheroes can sense the presence of the explosive triacetone triperoxide (TATP) if just a few molecules are present, on the scale of parts per trillion.

Researchers at the University of Rhode Island are striving to make a comparable device for detecting TATP in its vapor form. Their new detection system, which pairs a conductance sensor with a traditional thermodynamic sensor, confirms the presence of TATP at the level of parts per billion (ppb). Their work is described in a study published on 2 October in IEEE Sensors Letters.

Forget Moore’s Law—Chipmakers Are More Worried About Heat and Power Issues

Post Syndicated from Tekla S. Perry original https://spectrum.ieee.org/view-from-the-valley/semiconductors/design/power-problems-might-drive-chip-specialization

Power consumption and heat generation: these hurdles impede progress toward faster, cheaper chips, and are worrying semiconductor industry veterans far more than the slowing of Moore’s Law. That was the takeaway from several discussions about current and future chip technologies held in Silicon Valley this week.

John Hennessy—president emeritus of Stanford University, Google chairman, and MIPS Computer Systems founder—says Moore’s Law “was an ambition, a goal. It wasn’t a law; it was something to shoot for.”

U.S. Semiconductor Industry Veterans Keep Wary Eyes on China

Post Syndicated from Tekla S. Perry original https://spectrum.ieee.org/view-from-the-valley/semiconductors/devices/semiconductor-industry-veterans-keep-wary-eyes-on-china

How might the U.S. chip industry solve a problem like China?

A panel of semiconductor industry veterans took up this question at a Churchill Club event this week. The group generally expressed worry about the impact China will have on the future of the U.S. chip industry, and the lack of good ideas about how the U.S. industry can respond to threats posed by China.

“China is the ultimate conundrum,” says Stanford president emeritus and MIPS Computer Systems founder John Hennessy. “It’s a large market that U.S. companies need access to, together with being what will become a major technical competitor. We have never faced that.”

The consolidation of silicon manufacturing into two main foundries raises the threat level, pointed out Diane Bryant, former Intel and Google Cloud executive.

“You really just have TSMC and Samsung left,” she said. “And TSMC is in Taiwan, so you have to be thinking about China and the threat to Taiwan, and what will happen to TSMC.”

China will take over Taiwan “the same time North Korea takes over South Korea,” quipped Hennessy, giving it control over most of the world’s semiconductor manufacturing capabilities.

“What do you do tomorrow if TSMC and Samsung are off limits?” he asked his fellow panel members.

“You can’t go to Global Foundries,” which indeed has some U.S. semiconductor manufacturing capability, said Bryant, “unless you really want Moore’s Law to be dead.” (Global Foundries recently stopped developing the most advanced semiconductor processes.) 

Rodrigo Liang, CEO of SambaNova Systems, argued that fixing this problem can only be done at the level of the U.S. government.

Pradeep Sindhu, founder of Juniper Networks and founder and CEO of Fungible, agreed. “The U.S. government needs an industrial policy,” he said, “and it doesn’t have one.”

The foundry issue is a long-term problem. Perhaps a nearer term question is how the growing capability of China’s tech industry will impact U.S.-based companies.

“China is talking about becoming tech independent, becoming net exporters,” said Bryant. “We can talk about how many years [it will take], but it is inevitable.”

Companies in China will catch up for several reasons, panelists indicated. For one, said Sindhu, they are very hungry to learn.

For another, said Navin Chaddha, managing director of the Mayfield Fund, China’s huge market gives Chinese companies a boost. “Usually innovation happens when you are close to a market,” he said. To date, the U.S. companies and Samsung have benefitted from the boom” in the Chinese tech market, but now “we are seeing Chinese companies benefitting from their local market… and China is the biggest market when it comes to broadband users.”

A solution?

“Invest in that market,” says Chaddha.

That strategy is not without pitfalls, Hennessy indicated. “What happens to your technology when you ship it over there?” he asked.

“To the extent that we can protect it, we will,” Sindhu said.

Hennessy remained skeptical. “Just wait until you sign the deal and send it over,” he said.

“This isn’t a redo of semiconductor wars with Japan in the 80s,” he concluded.  “This is a country that has scale, that has entrepreneurial zeal. They will give us a run for the money.”

Next-Gen AR Glasses Will Require New Chip Designs

Post Syndicated from Tekla S. Perry original https://spectrum.ieee.org/view-from-the-valley/semiconductors/design/dramatic-changes-in-chip-design-will-be-necessary-to-make-ar-glasses-a-reality

What seems like a simple task—building a useful form of augmented reality into comfortable, reasonably stylish, eyeglasses—is going to need significant technology advances on many fronts, including displays, graphics, gesture tracking, and low-power processor design.

That was the message of Sha Rabii, Facebook’s head of silicon and technology engineering. Rabii, speaking at Arm TechCon 2019 in San Jose, Calif., on Tuesday, described a future with AR glasses that enable wearers to see at night, improve overall eyesight, translate signs on the fly, prompt wearers with the names of people they meet, create shared whiteboards, encourage healthy food choices, and allow selective hearing in crowded rooms. This type of AR will be, he said, “an assistant, connected to the Internet, sitting on your shoulders, and feeding you useful information to your ears and eyes when you need it.”

X-Ray Tech Lays Chip Secrets Bare

Post Syndicated from Samuel K. Moore original https://spectrum.ieee.org/nanoclast/semiconductors/design/xray-tech-lays-chip-secrets-bare

Scientists and engineers in Switzerland and California have come up with a technique that can reveal the 3D design of a modern microprocessor without destroying it.

Typically today, such reverse engineering is a time-consuming process that involves painstakingly removing each of a chip’s many nanometers-thick interconnect layers and mapping them using a hierarchy of different imaging techniques, from optical microscopy for the larger features to electron microscopy for the tiniest features. 

The inventors of the new technique, called ptychographic X-ray laminography, say it could be used by integrated circuit designers to verify that manufactured chips match their designs, or by government agencies concerned about “kill switches” or hardware trojans that could have secretly been added to ICs they depend on.

“It’s the only approach to non-destructive reverse engineering of electronic chips—[and] not just reverse engineering but assurance that chips are manufactured according to design,” says Anthony F. J. Levi, professor of electrical and computer engineering at University of Southern California, who led the California side of the team. “You can identify the foundry, aspects of the design, who did the design. It’s like a fingerprint.”

Microsize Lens Pushes Photonics Closer to an On-Chip Future

Post Syndicated from Mark Anderson original https://spectrum.ieee.org/nanoclast/semiconductors/optoelectronics/microsize-lens-pushes-photonics-closer-to-an-onchip-future

Optical microcomputing, next-generation compact LiDAR units, and on-chip spectrometers all took a step closer to reality with the recent announcement of a new kind of optical lens.

The lens is not made of glass or plastic, however. Rather, this low-loss, on-chip lens is made from thin layers of specialized materials on top of a silicon wafer. These “metasurfaces” have shown much promise in recent years as a kind of new, microscale medium for containing, transmitting, and manipulating light.

Photonics at the macro-scale is more than 50 years old and has applications today in fields including telecommunications, medicine, aviation, and agriculture. However, shrinking all the elements of traditional photonics down to microscale—to match the density of signals and processing operations inside a traditional microchip—requires entirely new optical methods and materials.

A team of researchers at the University of Delaware, including Tingyi Gu, an assistant professor of electrical and computer engineering, recently published a paper in the journal Nature Communications that describes their effort to build a lens from a thin metasurface material on top of a silicon wafer.

Gu says that metasurfaces have typically been made from thin metal films with nanosized structures in it. These “plasmonic” metasurfaces offered the promise of, as a Nature Photonics paper from 2017 put it, “Ultrathin, versatile, integrated optical devices and high-speed optical information processing.”

The problem, Gu says, is that these “plasmonic” materials are not exactly transparent like windowpanes. Traveling just fractions of a micrometer can introduce signal loss of a few decibels to tens of dB.

“This makes it less practical for optical communications and signal processing,” she says.

Her group uses an alternate kind of metasurface made from etched dielectric materials atop silicon wafers. Making optical components out of dielectric metasurfaces, she says, could sidestep the signal loss problem. Her group’s paper notes that their lens introduces a signal loss of less than one dB.

Even a small improvement (and going from handfuls of dB down to fractions of a dB is more than small) would make a big difference, because a real-world photonics chip might one day have many such components in it. And the more lossy the photonics chip, the greater the amount of laser power needed to be pumped through the chip. More power means more heat and noise, which might ultimately limit the extent to which the chip could be miniaturized. But with her team’s dielectric metasurface lens, “We can make a device much smaller and more compact,” she says.

Her group’s lens is made from a configuration of gratings etched in the metasurface — following a wavy pattern of vertical lines that looks a bit like the Cisco company logo. Gu’s group was able to achieve some of the familiar properties of lenses, including converging beams with a measurable focal length (8 micrometers) and object and image distance (44 and 10.1 µm).

The group further used the device’s lensing properties to achieve a kind of optical signal Fourier Transform—which is also a property of classical, macroscopic lenses.

Gu says that next steps for their device include exploring new materials and to work toward a platform for on-chip signal processing.

“We’re trying to see if we can come up with good designs to do tasks as complicated as what traditional electronic circuits can do,” she says. “These devices have the advantage that they can process signals at the speed of light. It doesn’t need logic signals going back and forth between transistors. … It’s going to be fast.”

Custom Computer Makes Inverse Lithography Technology Practical for First Time

Post Syndicated from Samuel K. Moore original https://spectrum.ieee.org/nanoclast/semiconductors/materials/custom-computer-makes-inverse-lithography-practical-for-first-time

Silicon Valley-based D2S revealed last week that it had solved the last problem in a nascent technique called inverse lithography technology, or ILT. The breakthrough could speed the process of making chips and allow semiconductor fabs to produce more advanced chips without upgrading equipment. The solution, a custom-built computer system, reduces the amount of time needed for a critical step from several weeks to a single day.

In most of the photolithography used to make today’s microchips, light with a wavelength of 193-nanometers is shown through lenses and a patterned photomask, so that the pattern is shrunk down and projected onto the silicon wafer where it defines device and circuit features. (The most modern chip making technology, extreme ultraviolet lithography, works a bit differently. But, only a few chipmakers have these tools.)

Scientists Wind Wires and Drip Semiconductors to Make Transistors on a Thread

Post Syndicated from XiaoZhi Lim original https://spectrum.ieee.org/tech-talk/semiconductors/devices/transistors-on-a-thread

Flexible electronics that could be worn on, stuck to, or even implanted in your body need to be able to twist, bend, or fold. And when it comes to that range of motion, nothing beats a single thread.

“Threads are the ultimate in flexibility,” says Sameer Sonkusale, an electrical engineer at Tufts University.

In 2016, Sonkusale and his team used cotton threads to create microfluidic sensors that can measure things like temperature and pH. Last month, in a proof-of-concept experiment, Sonkusale’s group reported making thread-based transistors, and demonstrated their utility as logic gates and multiplexers.