Photonics - Page 6

Researchers from China's Xi'an Jiaotong University suggest a new bio-inspired soft robot platform made from graphene composites. The graphene robot is driven by near-infrared (nIR) light as graphene has excellent photothermal conversion efficiency in the nIR light band.

The team suggests building a microfish made from graphene and polymers. The microfish is controlled by nIR light. This is bilayer (pure-PDMS and GNP-PDMS) platform that is easily produced by scraping coating and spin coating processing. The bilayer platform is a soft photoresponsive material that can work in both air and water.

Researchers from the University of Manchester (with help from an international team of scientists) discovered that if you stack two graphene sheets on on top of the other (bi-layer graphene) in a certain way, it actually cools down when hit with laser light.

The two graphene sheets are aligned so one sheet is rotated by 11.3 degrees. With a specific laser energy, instead of heating up like any "normal" material - it cools down. The researchers explain that the photons of the laser absorb the vibration energy of the atoms - instead of the other way around.

AMO GmBH, in collaboration with Alcatel Lucent Bell Labs, developed a graphene-based photodetector with a maximum data rate of 50 Gbit/s. They say this is the world's fastest photodetector.

The graphene is used as the active element in this design, and the detector also uses nickel/aluminum (Ni/Al), hydrogen silsesquioxane (HSQ), and buried oxide (BOX). This research project was supported by the EU's Graphene Flagship project.

The National Science Foundation of China (NSFC) awarded an 18-month Young International Researcher Fellowship to a University of Cambridge researcher that will look to se graphene materials composites for organic optoelectronic compounds. The researcher hope to use inkjet printers to produce those devices and then integrate them into displays, light detectors and gas sensors.

In plain English, it means that they hope these kind of devices will enable flexible, cheap and fast cameras. Compared to current printed organic circuits, the graphene-based will be less sensitive to temperature and moisture and will also offer much faster response time that is suited for photodetection.

Researchers from the University of Manchester developed a new way to modify the transmission of light that goes through a silicon wire (waveguide) - by wrapping graphene around the wire. Such silicon waveguide can be used to build a photonic microchip, and have also applications in highly sensitive bio-chemical sensor devices and perhaps photo detectors too.

The waveguides in this research are built in loops shaped like oval racetracks - and are called racetrack resonators. In a bio-chemical sensor, the light that leaks out of the waveguide is used for chemical sensing. The graphene coating adds further capabilities to such a sensor, such as making it more sensitive and selective. The researchers say that the graphene dramatically alters the way the light is guided through the device.

Last month we reported that researchers from Beijing are developing graphene-enhanced titanium alloys that may be useful as a new material for aircraft. Today we learn that the Chinese are not alone in their graphene efforts for the aerospace industry.

So first up with a new research by the University of Manchester, that developed new carbon fibers using a composite material made from two layers of polymer with a graphene sheet placed between them. Using Raman Spectroscopy, the researchers measured these fibers and found them to be very strong, even when stretched. The researchers say that these can be used to make structural, lightweight components for fuel efficient cars and aircraft.

Researchers from Berkeley Lab and the University of California (UC) Berkeley developed a method to open a bandgap in a graphene boron-nitride (GBN) heterostructure using visible light. Using this so called "photo-induced doping" of the GBN the researchers created pn junctions and other useful doping profiles while preserving the material’s remarkably high electron mobility.

Using visible light is very promising as this technique is very flexible and (unlike electrostatic gating and chemical doping) does not require multi-step fabrication processes that reduce the graphene's quality. Using this method, one can make and erase different patterns easily.

Researchers at Melbourne's Swinburne University developed a high-quality continuous graphene oxide thin film that has a record-breaking optical nonlinearity. The film may be suitable for high performance integrated photonic devices - useful for communication, biomedcine and photonic computing.

To create this new film, the researchers first spin-coated a graphene-oxide solution on a glass substrate. They then used a laser to create microstructures on the graphene oxide film to tune the nonlinearity of the material. Now they have a platform to fabricate optical components with desired nonlinearity - and all on the same graphene sheet without the need to integrate different components.

Researchers from Monash University use graphene and carbon nanotubes to develop a spaser (a nano-laser that emits a beam of light through the vibration of free electrons unlike the electromagnetic wave-emission process of regular lasers).

This new spaser is more robust and flexible compared to regular spasers made from silver and quantum-dots. It can also withstand high temperatures and is eco-friendly.

The EU launched a new project called Graphenics that aims to develop an ultra-compact graphene-based mid-infrared broadband light source. The project include researchers from Belgium, Austria, Poland and Canada. The hope to achieve a highly compact and portable device, that will pave the way to mid-infrared broadband light sources in applications such as medical diagnostics and optical safety testing of water.

The researchers say that the main issue stopping the widespread adoption of broadband mid-infrared light source is the source compactness and portability. The researchers hope to develop a chip in which both the chip and the pump laser exciting the chip are made extremely compact.