Skip to main content

Diamond-like photonic nanocrystal: Perfect omnidirectional reflector

Through advanced calculations physicists and mathematicians have discovered that a thin, diamond-like photonic nanostructure reflects a surprisingly broad range of colors of light, from all angles. This causes the material to have great potential as a back reflector to enhance the efficiency of solar cells or tiny on-chip light sources.
The efficiency of solar cells depends on trapping and absorbing light and can be increased by using a back reflector: a mirror behind the solar cell material that reflects light that was not absorbed and leads it back into the solar cell. The ideal mirror reflects light incident from any angle, known as omnidirectional reflectance, and for all frequencies (or colors) of light. Such omnidirectional reflectance for dielectric structures is associated with three-dimensional photonic crystal nanostructures that sustain a so-called complete photonic band gap. However, researchers always thought such structures would have a narrow frequency range of operation and their omnidirectional behavior has never been demonstrated to date.
An interdisciplinary team of physicists and mathematicians from the University of Twente has now performed advanced calculations on a very promising material developed in the Complex Photonic Systems group. "We studied so-called inverse woodpile photonic crystals," says PhD student Devashish. "These crystals consist of regularly ordered array of pores drilled in two perpendicular directions in a wafer of dielectric such as silicon. The crystal structure is inspired by diamond gemstones."
The researchers studied the reflectivity of the cubic diamond-like inverse woodpile crystals by numerical calculations and interpreted recent experiments. They employed the finite element method to study these crystals surrounded by free space. "We found that even very thin inverse woodpiles strongly reflect many colors of light omnidirectionally," Devashish says. "In inverse woodpiles, the absorption of light is negligible. This makes them a great candidate as a back reflector in solar cells. We also expect these diamond-like photonic crystals may lead to on-chip lasers, invisibility cloaks and devices to confine light in extremely small volumes."
Source
  1. D. Devashish, Shakeeb B. Hasan, J. J. W. van der Vegt, Willem L. Vos. Reflectivity calculated for a three-dimensional silicon photonic band gap crystal with finite support. Physical Review B, 2017; 95 (15) DOI: 10.1103/PhysRevB.95.155141
  2. University of Twente. "Thin diamond crystal reflects many colors of light in all directions." ScienceDaily. ScienceDaily, 1 May 2017.
Labels:

Comments

Post a Comment

Popular posts from this blog

Nanoimprinting accelerating the fabrication of nano-optical devices

Combining speed with incredible precision, a team of researchers has developed a way to print a nanoscale imaging probe onto the tip of a glass fiber as thin as a human hair, accelerating the production of the promising new device from several per month to several per day. The high-throughput fabrication technique opens the door for the widespread adoption of this and other nano-optical structures, which squeeze and manipulate light in ways that are unachievable by conventional optics. Nano-optics have the potential to be used for imaging, sensing, and spectroscopy, and could help scientists improve solar cells, design better drugs, and make faster semiconductors. A big obstacle to the technology's commercial use, however, is its time-consuming production process. The new fabrication method, called fiber nanoimprinting, could unplug this bottleneck. It was developed by scientists at the Molecular Foundry, located at the Department of Energy's Lawrence Berkeley Nat...
Post a Comment
Read more

Intel's upcoming 10-nanometer chip manufacturing technology

At long last, chip giant  Intel  (NASDAQ: INTC) opened up about its upcoming 10-nanometer chip manufacturing technology, at its first-ever Technology and Manufacturing Day. The company has -- frustratingly -- kept key details of this technology under wraps for years now, but Intel is now putting them out there for all to see.  Without further ado, let's look at what Intel had to tell us about this new tech. A large jump in density Let's talk performance Competitive comparison and no yield information Image source: Intel. Chipmakers generally like to reduce the area of its transistors with major new technology shifts. This area reduction is important in reducing transistor costs on a yield-normalized basis, a really important factor for product cost. Chipmakers are ultimately able to cram more features and functionality into a chip while maintaining reasonable cost structures. Intel says that in moving from 14 nanometers to 10, it's delivering an incre...
Post a Comment
Read more

Hybrid graphene and CNT anode battery

Rice University scientists have created a rechargeable lithium metal battery with three times the capacity of commercial lithium-ion batteries by resolving something that has long stumped researchers: the dendrite problem. The Rice battery stores lithium in a unique anode, a seamless hybrid of graphene and carbon nanotubes. The material first created at Rice in 2012 is essentially a three-dimensional carbon surface that provides abundant area for lithium to inhabit. The anode itself approaches the theoretical maximum for storage of lithium metal while resisting the formation of damaging dendrites or "mossy" deposits. Dendrites have bedeviled attempts to replace lithium-ion with advanced lithium metal batteries that last longer and charge faster. Dendrites are lithium deposits that grow into the battery's electrolyte. If they bridge the anode and cathode and create a short circuit, the battery may fail, catch fire or even explode. Rice researchers led by chemist...
Post a Comment
Read more