Category Physics

Light from an optical fiber illuminates the metasurface, is scattered in four different directions, and the intensities are measured by the four detectors. From this measurement the state of polarization of light is detected. Credit: Capasso Lab/Harvard SEAS

What do astrophysics, telecommunications and pharmacology have in common? Each of these fields relies on polarimeters – instruments that detect the direction of the oscillation of electromagnetic waves, ie polarization of light.

When light is reflected or scattered off an object, its polarization changes and measuring that change reveals a lot of information. Astrophysicists, for example, use polarization measurements to analyze the surface of distant, or to map the giant magnetic fields spanning our galaxy...

Secretion in droplet-embedded gel permits self-repairing behavior. Three-dimensional confocal fluorescence images show damaged gel (top) after 0.5 hours and the self-repaired gel after 72 hours (bottom). Credit: Image courtesy of Joanna Aizenberg

Inspired by healing wounds in skin, a new approach protects and heals surfaces using a fluid secretion process. In response to damage, dispersed liquid-storage droplets are controllably secreted. The stored liquid replenishes the surface and completes the repair of the polymer in seconds to hours.

The fluid secretion approach to repair the material has also been demonstrated in fibers and microbeads...

Figure 1 shows interconnected graphene nanoribbons (GNRs). The interconnection points are observed as elbow structures. The inset of (a) shows the chemical structure of an elbow interconnection point of two chiral-edge GNRs. The top panel of (b) shows the scanning tunneling microscopy topograph, highlighting a single GNR and a pair of connected GNRs (elbow). The bottom panel of (b) shows the local density of states (LDOS) of these two structures share the same electronic architecture, including the elbow interconnection point. This indicates that electronic properties, such as electron and thermal conductivities, should be comparable between termini 1-2 and termini 3-4. Credit: Patrick Han

Chemical interconnection bridges electronic properties of graphene-nanoribbons with zigzag-edge featu...

A schematic of the new laser system. Credit: Image courtesy of Northwestern University

High power and rapid tuning for the detection of hazardous chemicals. From their use in telecommunication to detecting hazardous chemicals, lasers play a major role in our everyday lives. They keep us connected, keep us safe, and allow us to explore the dark corners of the universe. Now a Northwestern University team has made this ever-important tool even simpler and more versatile by integrating a mid-infrared tunable laser with an on-chip amplifier. This breakthrough allows adjustable wavelength output, modulators, and amplifiers to be held inside a single package.

With this architecture, the laser has demonstrated an order-of-magnitude more output power than its predecessors, and the tuning range has ...