Showing posts with label light. Show all posts
Showing posts with label light. Show all posts

Monday, 6 February 2017

Scientists Have Imaged Light Going Faster Than Itself

At the University of Washington in St. Louis a group of researchers have taken instances of a laser that generates an optical shock where a Mach cone is being equivalent to a sonic boom, only for light. It is necessary to have an optical Mach cone, which is a pulse of light to travel faster in comparison to the emitting waves.

But, the researchers have proved their excellence by developing features of a laser beam that will interact separately with velocity, wavelength, and frequency. They have tried and directed the laser beam pass through a nuanced confection of panels of silicone, aluminum oxide powder, and dry ice. The crux of the whole procedure was to figure out that light moves faster than the generating waves as they pass in terms with the layers, and leaves behind the Optical Mach cone.

In order to capture the cone, the researchers have set up CCD cameras beside the apparatus that generates cone. One of the camera was a steak one, which is very beneficial in exfoliating the movement of all the charged particles that will create a distinguished profile for the pulse that will enable the waveform to be characterized in 3-space over the time period.

With the use of steak camera and the CCD, the researchers have managed to capture a 2D sequence of the pictures from almost three perspectives that too in a single take. After this they stroked the picture like a CAT, inorder to scan it to make the cone into a 3D model.

The lead author of this experiment called Jinyang Laing has declared that this development is done not only in terms with physics, but in neuroscience as well. He further adds that such an imagining can capture and develop 100 billion frames that too in flick of seconds. He even added that if the temporal resolution is of this sort then the day is not far away when they will be able to get hold of neurons being fired in real time.

There are several epitomizing ways through which we can visualize several things which are actually invisible and goes at a speed that regulate shockwaves and these are none other than the Mach diamonds.

Mach diamonds are a set of waves that are invisible, present in the form of an exhaust plume and are most commonly found in the Raptor’s fiery tail. They are also known as thrust diamonds and there are ample reasons why they are a familiar sight to everyone and are seemed to be discovered behind F-16s, F-22s, and the SR-71 Blackbird. Though, a suitable attitude is desirable to get a clear vision of these thrust diamonds behind the Blackbird.

Shockwaves are quiet easy to be photographed if your camera setup is accurate. This is generally photographed with the help of a method called Schlieren, which ensures images being captured at a very high speed and it simultaneously compares the image with the background in order to be sure to locate the exact position through which the wave must have distorted through the frame.

Wednesday, 25 February 2015

Interaction between Light and Sound in Nanoscale Waveguide

Interaction between Light & Sound – Nanoscale Area

Scientists of Belgium from Ghent University and Nano-electronics research institute, Imec, had a demonstration on the interaction between light and sound in a nanoscale area and their discovery published in the Nature Photonics indicate that the physics of light matter coupling at the level of nanoscale, has paved the way for enhanced signal process on mass producible silicon photonic chips.

The field of silicon in the last decade has attracted increased attention as a driver of lab-on-a-chip biosensors as well as of faster-than-electronics communication between the computer chips. The technology has been built on nanoscale structures which are called silicon photonic wires that are roughly hundred times narrower than human hair and these nanowires tend to carry optical signal from one point to another at the speed of light and are developed with the same technology to fabricate electronic circuitry.

 The wires tends to operate since light moves slower in the silicon core than the surrounding air and glass and due to the trapped light in the wire by the phenomenon of total internal reflection.

Sound Moves Quicker in Silicon Wires 

Confining light simply is one thing though manipulating it is another and the problem is that one light beam cannot change easily the properties of another. It is here that the light matter interaction is in focus which enables some photons to control the other photons.

Researchers from Imec as well as the Photonics Research Group of Ghent University portrayed a peculiar form of light matter interaction and managed to confine light as well as sound to the silicon nanowires where the sound oscillates ten billion times per second which is far more rapid that human ears can hear. They realized that the sound cannot remain trapped in the wire by total internal reflection and unlike light; sound tends to move much quicker in the silicon core than the surrounding air and glass.

The scientistsframed the environment of the core in order to make sure any vibrational wave intending to escape it would eventually bounce back and in doing so, they confined light as well as sound to the same nanoscale waveguide core, a first observation.

Light & Vibration Influence Each Other 

Light and vibrations strongly influenced each other when trapped in an incredibly small area, where light tends to generate sound and sound shifts the colour of light which is a process known as stimulated Brillouin scattering.

They exploited the interaction in order to amplify specific colour of light, anticipating that the demonstration would open up new ways in manipulating optical information such as light pulses could be converted into sonic pulses and back into light, by implementing the much needed delay lines.

Moreover the researchers are expecting that the similar techniques could also be applied to even smaller entities like viruses and DNA since these particles tend to have unique acoustic vibration which could be used to probe their global structure.