New type of graphene photodetector could enable low-cost cameras for self-driving cars and robots

An international team of researchers recently reported its success in creating a new type of graphene-based photodetector.

The team integrated three concepts to achieve the new device: metallic plasmonic antennas, ultra sub-wavelength waveguiding of light and graphene photodetection. Specifically, the 2D-material hexagonal boron nitride was used as the waveguide for hyperbolic phonon polaritons, which can highly confine and guide mid-infrared light at the nanoscale. By carefully matching the nano-antenna with the phonon polariton waveguide, they efficiently funnel incoming light into a nanoscale graphene junction. By using this approach, they were able to overcome intrinsic limitations of graphene, such as its low absorption and its small photoactive region near the junction.

New twist on graphene to boost optoelectronics

Researchers at University of California Berkeley, Washington University in St. Louis and Lawrence Berkeley National Laboratory have stacked two sheets of graphene on top of each other and twisted them, which resulted in the conversion of a common linear material into one with nonlinear optical capabilities. This could prove useful for various everyday technologies — from spectroscopy and material analysis to communications and computing.

In the study of optics, scientists distinguish between linear and nonlinear materials. Most materials, including sheets of graphene, are linear. If you shine red light at a sheet of graphene, the photons will either be absorbed or scattered, but in any case - they will remain red.

Researchers design graphene-based broadband detector of terahertz radiation

Scientists from Russia and Germany have created a graphene-based broadband detector of terahertz radiation. The device could have potential for applications in communication and next-generation information transmission systems, security and medical equipment.

Graphene detector reveals THz light’s polarization image(a) shows a top view of the device, with the sensitive region magnified in (b). The labels S, D, and TG denote the source, drain, and top gate. A side section of the detector is shown in (c). Image from MIPT

The new detector relies on the interference of plasma waves. Plasma waves in metals and semiconductors have recently attracted much attention from researchers around the world. Like the more familiar acoustic waves, the ones that occur in plasmas are essentially density waves, too, but they involve charge carriers: electrons and holes. Their local density variation gives rise to an electric field, which nudges other charge carriers as it propagates through the material. This is similar to how the pressure gradient of a sound wave impels the gas or liquid particles in an ever expanding region. However, plasma waves die down rapidly in conventional conductors.

Talga Resources fast-tracks graphene-enhanced silicon anode product

Talga Resources logo 2017Talga Resources has provided an update on the commercial progress of its graphene-enhanced silicon anode lithium-ion battery product Talnode-Si. Following encouraging early test results, further technical and commercial development of Talnode-Si has been underway at Talga’s facilities in Europe.

Results from this latest phase of development reportedly show continued success of Talga’s silicon anode approach which uses lower-cost metallurgical-grade silicon for a high-energy density anode with mass-producibility potential.

Research team develops new method to generate precisely controlled graphene microbubbles

Researchers at Swinburne University of Technology recently teamed up with teams from National University of Singapore, Rutgers University, University of Melbourne, and Monash University, to develop a method to generate precisely controlled graphene microbubbles on a glass surface using laser pulses.

Schematic of optical setup for characterizing the GO microbubbles imageSchematic of optical setup for characterizing the GO microbubbles. Image from article

Microbubbles - around 1-50 micrometers in diameter - can have various applications like drug delivery, membrane cleaning, biofilm control, and water treatment. They've been applied as actuators in lab-on-a-chip devices for microfluidic mixing, ink-jet printing, and logic circuitry, and in photonics lithography and optical resonators. They also have great potential for other biomedical imaging and applications like DNA trapping and manipulation applications.