Posts belonging to Category photonics

Green Solar Panels And Other Colors

Researchers from AMOLF, the University of Amsterdam (UvA) and the Energy Research Centre of the Netherlands (ECN) have developed a technology to create efficient bright green colored solar panels. Arrays of silicon nanoparticles integrated in the front module glass of a silicon heterojunction solar cell scatter a narrow band of the solar spectrum and create a green appearance for a wide range of angles. The remainder of the solar spectrum is efficiently coupled into the solar cell. The current generated by the solar panel is only  reduced by 10%. The realization of efficient colorful solar panels is an important step for the integration of solar panels into the built environment and landscape.
research has much focused on maximizing the electricity yield obtained from solar panels: nowadays, commercial panels have a maximum conversion efficiency from sunlight into electricity of around 22%. To reach such high efficiency, silicon solar cells have been equipped with a textured surface with an antireflection layer to absorb as much light as possible. This creates a dark blue or black appearance of the solar panels.

To create the colored solar panels the researchers have used the effect of Mie scattering, the resonant backscattering of light with a particular color by nanoparticles. They integrated dense arrays of silicon nanocylinders with a diameter of 100 nm in the top module cover slide of a high-efficiency silicon heterojunction solar cell. Due to the resonant nature of the light scattering effect, only the green part of the spectrum is reflected; the other colors are fully coupled into the solar cell. The current generated by the mini solar panel (0,7 x 0,7 cm2)  is only reduced by 10%. The solar panel appears green over a broad range of angles up to 75 degrees. The nanoparticles are fabricated using soft-imprint lithography, a technique that can readily be scaled up to large-area fabrication.
The light scattering effect due to Mie resonances is easily controllable: by changing the size of the nanoparticles the wavelength of the resonant light scattering can be tuned. Following this principle the researchers are now working to realize solar cells in other colors, and on a combination of different colors to create solar panels with a white appearance. For the large-scale application of solar panels, it is essential that their color can be tailored.

The new design was published online in the journal Applied Physics Letters.


Chinese Quantum Satellite Sends ‘Unbreakable’ Code

China has sent an “unbreakablecode from a satellite to the Earth, marking the first time space-to-ground quantum key distribution technology has been realized, state media said. China launched the world’s first quantum satellite last August, to help establish “hack proofcommunications, a development the Pentagon has called a “notable advance“. The official Xinhua news agency said the latest experiment was published in the journal Nature, where reviewers called it a “milestone“.

The satellite sent quantum keys to ground stations in China between 645 km (400 miles) and 1,200 km (745 miles) away at a transmission rate up to 20 orders of magnitude more efficient than an optical fiber, Xinhua cited Pan Jianwei, lead scientist on the experiment from the state-run Chinese Academy of Sciences, as saying.

That, for instance, can meet the demand of making an absolute safe phone call or transmitting a large amount of bank data,” Pan said. Any attempt to eavesdrop on the quantum channel would introduce detectable disturbances to the system, Pan said. “Once intercepted or measured, the quantum state of the key will change, and the information being intercepted will self-destruct,” Xinhua said.

The news agency said there were “enormous prospects” for applying this new generation of communications in defense and finance.


New WIFI Speeds Up To 300 Times Faster

Researchers at the Eindhoven University of Technology (Netherlands) say their new wireless network that uses harmless infrared rays will make wifi speeds up to 300 times faster.


“What we are doing actually is using rays of light which convey the information in a wireless way, and each ray is acting as a very high capacity channel. It’s actually the same as an optical fibre without needing the fibre, and what we achieved up to this moment is 112 gigabits per second,” says Professor Ton Koonen, Eindhoven University of Technology.

That’s the equivalent data of three full-length movies being downloaded per second. Light antennas radiate multiple invisible wavelengths at various angles. If a user’s smartphone or tablet moves out of one antenna’s sightline, another takes over. Infrared wavelengths don’t go into your eyes, making them safe to use. The lack of moving parts makes the system maintenance and power-free. While each user gets their own antenna.

The big benefits we see of our technique is that you offer unshared capacity to each individual user, so you get a guaranteed capacity. Next to that you only get a beam if you need the traffic. So we’re not illuminating the whole place where maybe a single user is there. That means it’s much more power efficient. Another efficiency, another advantage, is that light doesn’t go through walls. So that means your communication is really confined to the particular room. Nobody can listen in from outside, so it offers you a lot of security,” explains rofessor Ton Koonen.
The team is seeking funding to help make the technology widespread within five years.


No More Batteries For Cellphones

University of Washington (UW) researchers have invented a cellphone that requires no batteries — a major leap forward in moving beyond chargers, cords and dying phones. Instead, the phone harvests the few microwatts of power it requires from either ambient radio signals or light.

The team also made Skype calls using its battery-free phone, demonstrating that the prototype made of commercial, off-the-shelf components can receive and transmit speech and communicate with a base station.


We’ve built what we believe is the first functioning cellphone that consumes almost zero power,” said co-author Shyam Gollakota, an associate professor in the Paul G. Allen School of Computer Science & Engineering at the UW. “To achieve the really, really low power consumption that you need to run a phone by harvesting energy from the environment, we had to fundamentally rethink how these devices are designed.”

The team of UW computer scientists and electrical engineers eliminated a power-hungry step in most modern cellular transmissionsconverting analog signals that convey sound into digital data that a phone can understand. This process consumes so much energy that it’s been impossible to design a phone that can rely on ambient power sources. Instead, the battery-free cellphone takes advantage of tiny vibrations in a phone’s microphone or speaker that occur when a person is talking into a phone or listening to a call.

An antenna connected to those components converts that motion into changes in standard analog radio signal emitted by a cellular base station. This process essentially encodes speech patterns in reflected radio signals in a way that uses almost no power. To transmit speech, the phone uses vibrations from the device’s microphone to encode speech patterns in the reflected signals. To receive speech, it converts encoded radio signals into sound vibrations that that are picked up by the phone’s speaker. In the prototype device, the user presses a button to switch between these two “transmitting” and “listening” modes.

The new technology is detailed in a paper published July 1 in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies.


By 2025 Renewables Will Power 67 Percent Of South Australia

Declining renewables and energy storage costs will increasingly squeeze out gas-fired generation in South Australia as early as 2025, a joint research report conducted by Wood Mackenzie and GTM Research shows. The South Australia experience is noteworthy in a global power mix set to increasingly shift to renewable energy. South Australia retired its last coal plant in 2016 and is projected to have installed renewable energy capacity exceed its peak demand by 2020.

By 2025, wind, solar and battery costs will fall by 15 percent, 25 percent and 50 percent respectively. By then, renewables and batteries could offer a lower cost alternative to combined-cycle gas turbine plants, which are commonly used to manage base load power generation in South Australia. Meanwhile by 2035, renewables and batteries will provide a commercial solution for both base loads and peak loads. As a consequence, gas will increasingly be used just for emergency back-up.

One determining factor is the rate with which battery charging costs declines. By 2025, we expect battery charging cost to decrease as off-peak prices will gradually be set by excess wind generation. Battery storage then becomes a potential solution for managing peak loads,” said Bikal Pokharel, principal analyst for Wood Mackenzie‘s Asia-Pacific power and renewables .
By 2025 it’s expected that 67 percent of South Australia’s power capacity will come from renewables. Gas demand in the power sector will then decline by 70 percent.

Currently, South Australia’s peak loads are managed by open-cycle gas turbine (OCGT) plants. But by 2025, battery storage would be cheaper than OCGTs in managing peak loads even at gas price of A$7/mmbtu. OCGTs would then be relegated as emergency back-ups.”


New Solar System Produces 50 Percent More Energy

A concentrating photovoltaic system (CPV) with embedded microtracking can produce over 50 percent more energy per day than standard silicon solar cells in a head-to-head competition, according to a team of engineers who field tested a prototype unit over two sunny days last fall.

Solar cells used to be expensive, but now they’re getting really cheap,” said Chris Giebink, Charles K. Etner Assistant Professor of Electrical Engineering, Penn State. “As a result, the solar cell is no longer the dominant cost of the energy it produces. The majority of the cost increasingly lies in everything else — the inverter, installation labor, permitting fees, etc. — all the stuff we used to neglect.

This changing economic landscape has put a premium on high efficiency. In contrast to silicon solar panels, which currently dominate the market at 15 to 20 percent efficiency, concentrating photovoltaics focus sunlight onto smaller, but much more efficient solar cells like those used on satellites, to enable overall efficiencies of 35 to 40 percent. Current CPV systems are large — the size of billboards — and have to rotate to track the sun during the day. These systems work well in open fields with abundant space and lots of direct sun.

What we’re trying to do is create a high-efficiency CPV system in the form factor of a traditional silicon solar panel,” said Giebink.


SuperPowerful Tiny Device Converts Light Into Electricity

In today’s increasingly powerful electronics, tiny materials are a must as manufacturers seek to increase performance without adding bulk. Smaller also is better for optoelectronic devices — like camera sensors or solar cells —which collect light and convert it to electrical energy. Think, for example, about reducing the size and weight of a series of solar panels, producing a higher-quality photo in low lighting conditions, or even transmitting data more quickly.

However, two major challenges have stood in the way: First, shrinking the size of conventionally used “amorphousthin-film materials also reduces their quality. And second, when ultrathin materials become too thin, they are almost transparent — and actually lose some ability to gather or absorb light.

Now, in a nanoscale photodetector that combines both a unique fabrication method and light-trapping structures, a team of engineers from the University at Buffalo (UB) and the University of Wisconsin-Madison (UW-Madison) has overcome both of those obstacles. The researchers — electrical engineers Qiaoqiang Gan at UB, and Zhenqiang (Jack) Ma and Zongfu Yu at UW-Madison — described their device, a single-crystalline germanium nanomembrane photodetector on a nanocavity substrate, in the July 7, 2017, issue of the journal Science Advances.

This image shows the different layers of the nanoscale photodetector, including germanium (red) in between layers of gold or aluminum (yellow) and aluminum oxide (purple). The bottom layer is a silver substrate

We’ve created an exceptionally small and extraordinarily powerful device that converts light into energy,” says Gan, associate professor of electrical engineering in UB’s School of Engineering and Applied Sciences, and one of the paper’s lead authors. “The potential applications are exciting because it could be used to produce everything from more efficient solar panels to more powerful optical fibers.”

The idea, basically, is you want to use a very thin material to realize the same function of devices in which you need to use a very thick material,” says Ma, the Lynn H. Matthias Professor and Vilas Distinguished Achievement Professor in electrical and computer engineering at UW-Madison, also a lead author. Nanocavities are made up of an orderly series of tiny, interconnected molecules that essentially reflect, or circulate, light.

The new device is an advancement of Gan’s work developing nanocavities that increase the amount of light that thin semiconducting materials like germanium can absorb. It consists of nanocavities sandwiched between a top layer of ultrathin single-crystal germanium and a bottom, reflecting layer of silver.


How To Power The U.S. With Solar

Speaking recently at the National Governors Association Summer Meeting in Rhode Island, Elon Musk told his audience — including 30 United States governors — that it’s possible to power the nation with solar energy.

If you wanted to power the entire U.S. with solar panels, it would take a fairly small corner of Nevada or Texas or Utah; you only need about 100 miles by 100 miles of solar panels to power the entire United States,” Musk said. “The batteries you need to store the energy, to make sure you have 24/7 power, is 1 mile by 1 mile. One square-mile. That’s it.”

Why solar? Well, as Musk explained, as far as energy sources go, we can count on solar to come through for us: “People talk about fusion and all that, but the sun is a giant fusion reactor in the sky. It’s really reliable. It comes up every day. If it doesn’t we’ve got bigger problems.”

At present, about 10 percent of the U.S. is powered by renewable energy sources. To achieve a complete renewable energy power, Musk thinks solar is the way to go.

To start, he suggested combining rooftop solar and utility-scale solar plants. The former would be on the rooftops of houses in the suburbs, while the latter could power other areas. As we’ve seen with Tesla’s new rooftop solar unit, and efforts in other countries, like Australia, to build large-scale solar plants, this is a goal well within reach.

Next, while in transition from fossil fuel to solar, it’d be necessary to rely on other renewables. “We’ll need to be a combination of utility-scale solar and rooftop solar, combined with wind, geothermal, hydro, probably some nuclear for a while, in order to transition to a sustainable situation,” Musk explained.

Finally, the U.S. has to build more localized power sources, like the rooftop solar setups. “People do not like transmission lines going through their neighborhood, they really don’t like that, and I agree,” Musk said. “Rooftop solar, utility solar; that’s really going to be a solution from the physics standpoint. I can really see another way to really do it.”

When this happens, the U.S. would eliminate about 1,821 million metric tons of carbon dioxide (CO2) emissions generated by the country’s current electric power sector — 35 percent of the overall CO2 energy-related emissions in the U.S.


Solar Nanotechnology-based Desalination

A new desalination system has been developed that combines membrane distillation technology and light-harvesting nanophotonics. Called nanophotonics-enabled solar membrane distillation technology, or NESMD for short, the development has come from the Center for Nanotechnology Enabled Water Treatment (NEWT), based at Rice University. The system works whereby hot salt water is flowed across one side of a porous membrane and cold freshwater is flowed across the otherWater vapor is naturally drawn through the membrane from the hot to the cold side, and because the seawater doesn’t need to be boiled, the energy requirements are less than they would be for traditional distillation, according to the researchers. However, the energy costs are still significant because heat is continuously lost from the hot side of the membrane to the cold.

Unlike traditional membrane distillation, NESMD benefits from increasing efficiency with scale,” said Rice’s Naomi Halas, a corresponding author on the paper and the leader of NEWT‘s  nanophotonics research efforts. “It requires minimal pumping energy for optimal distillate conversion, and there are a number of ways we can further optimise the technology to make it more productive and efficient.

The distillation membrane in the chamber contained a specially designed top layer of carbon black nanoparticles infused into a porous polymer. The light-capturing nanoparticles heated the entire surface of the membrane when exposed to sunlight. A thin half-millimeter-thick layer of salt water flowed atop the carbon-black layer, and a cool freshwater stream flowed below.

Rice scientist and water treatment expert Qilin Li said the water production rate increased greatly by concentrating the sunlight: “The intensity got up 17.5 kilowatts per meter squared when a lens was used to concentrate sunlight by 25 times, and the water production increased to about 6 liters per meter squared per hour.”

In the PNAS study, researchers offered proof-of-concept results based on tests with an NESMD chamber about the size of three postage stamps and just a few millimeters thick.


Use The Phone And See 3D Content Without 3D Glasses

RED, the company known for making some truly outstanding high-end cinema cameras, is set to release a smartphone in Q1 of 2018 called the HYDROGEN ONE. RED says that it is a standalone, unlocked and fully-featured smartphone “operating on Android OS that just happens to add a few additional features that shatter the mold of conventional thinking.” Yes, you read that right. This phone will blow your mind, or something – and it will even make phone calls.

In a press release riddled with buzzwords broken up by linking verbs, RED praises their yet-to-be smartphone with some serious adjectives. If we were just shown this press release outside of living on RED‘s actual server, we would swear it was satire. Here are a smattering of phrases found in the release.

Incredible retina-riveting display
Holographic multi-view content
RED Hydrogen 4-View content
Assault your senses
Proprietary H3O algorithm
Multi-dimentional audio

  • There are two models of the phone, which run at different prices. The Aluminum model will cost $1,195, but anyone worth their salt is going to go for the $1,595 Titanium version. Gotta shed that extra weight, you know?

Those are snippets from just the first three sections, of which there are nine. I get hyping a product, but this reads like a catalog seen in the background of a science-fiction comedy, meant to sound ridiculous – especially in the context of a ficticious universe.

Except that this is real life.

After spending a few minutes removing all the glitter words from this release, it looks like it will be a phone using a display similar to what you get with the Nintendo 3DS, or what The Verge points out as perhaps better than the flopped Amazon Fire Phone. Essentially, you should be able to use the phone and see 3D content without 3D glasses. Nintendo has already proven that can work, however it can really tire out your eyes. As an owner of three different Nintendo 3DS consoles, I can say that I rarely use the 3D feature because of how it makes my eyes hurt. It’s an odd sensation. It is probalby why Nintendo has released a new handheld that has the same power as the 3DS, but dropping the 3D feature altogether.

Anyway, back to the HYDROGEN ONE, RED says that it will work in tandem with their cameras as a user interface and monitor. It will also display what RED is calling “holographic content,” which isn’t well-described by RED in this release. We can assume it is some sort of mixed-dimensional view that makes certain parts of a video or image stand out over the others.


Perovskite Solar Cells Conversion Efficiency Rises Up To 20%

A new low-temperature solution printing technique allows fabrication of high-efficiency perovskite solar cells with large crystals intended to minimize current-robbing grain boundaries. The meniscus-assisted solution printing (MASP) technique boosts power conversion efficiencies to nearly 20 percent by controlling crystal size and orientation.

The process, which uses parallel plates to create a meniscus of ink containing the metal halide perovskite precursors, could be scaled up to rapidly generate large areas of dense crystalline film on a variety of substrates, including flexible polymers. Operating parameters for the fabrication process were chosen by using a detailed kinetics study of perovskite crystals observed throughout their formation and growth cycle.

We used a meniscus-assisted solution printing technique at low temperature to craft high quality perovskite films with much improved optoelectronic performance,” said Zhiqun Lin, a professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. “We began by developing a detailed understanding of crystal growth kinetics that allowed us to know how the preparative parameters should be tuned to optimize fabrication of the films.”

The new technique is reported in the journal Nature Communications.


Solar Energy Transforms Salt Water Into Fresh Drinking Water

A federally funded research effort to revolutionize water treatment has yielded an off-grid technology that uses energy from sunlight alone to turn salt water into fresh drinking water. The desalination system, which uses a combination of membrane distillation technology and light-harvesting nanophotonics, is the first major innovation from the Center for Nanotechnology Enabled Water Treatment (NEWT), a multi-institutional engineering research center based at Rice University.

NEWT’s “nanophotonics-enabled solar membrane distillation” technology, or NESMD, combines tried-and-true water treatment methods with cutting-edge nanotechnology that converts sunlight to heat. More than 18,000 desalination plants operate in 150 countries, but NEWT’s desalination technology is unlike any other used today.

Direct solar desalination could be a game changer for some of the estimated 1 billion people who lack access to clean drinking water,” said Rice scientist and water treatment expert Qilin Li, a corresponding author on the study. “This off-grid technology is capable of providing sufficient clean water for family use in a compact footprint, and it can be scaled up to provide water for larger communities.”

The technology is described online in the Proceedings of the National Academy of Sciences.