Silicon Photonics Helps Produce Simple near Perfect Mirrors

Fact: Using a layer of self-assembled particles allows researcher to etch an almost-perfect reflector.

Using metamaterial created out of silicon scientists have created a way to create an almost-perfect reflector that would be used for lasers and telescopes.

The world has become increasingly fascinated with worlds beyond our own, more so, the cosmos. To get a better understanding of the stars and planets/exoplanets near and far, scientists require the best telescopes that will reflect perfect light. Recently published in ACS Photonics of 8 May 2015, advantages have been taken from dielectric metamaterials than plasmonic materials because it offers low-loss alternatives.

With the help of this material and the focus on an alternative method, it helps separate the electric and magnetic resonances to achieve the required reflection bandwidth while maintaining high tolerance to disorder. In other words, the material helps produce a sharper more accurate reflection while allowing scientists to scan different bandwidths with ease, with high resolution and very very minimal loss.

For instance, the bathroom mirror we use to check ourselves out in is a piece of glass backed by smooth aluminum film and reflects approximately 90% of visible light, which is good enough for us but not high performance application. So what makes these mirrors different is that they are made up of ‘Bragg Reflectors’ (stacks of films that refract light in such a way that is almost produces 100% of incident light at pretty much any wavelength of interest). Down side is that they are costly to produce.

How was this done? Jason Valentine, a mechanical engineer at Vanderbilt University, and colleagues demonstrated that using that addition of metal films and near perfect Bragg reflectors, while using a silicon wafer surface (silicon cylinders a few hundred nanometers in diameter), each of the cylinders acted like a tiny resonator for individual light frequencies. By controlling the size of the cylinder, Valentine controlled how well they reflected light of a given frequency. This mirror he created reflected 99% of light at peak wavelength.

Explanations

Metamaterials are materials that contain properties that have not yet been found in nature. They are used to assemble multiple elements that have been fashioned together (e.g. metals or plastics). These materials are usually arranged in a repeating pattern and often at microscopic or small scaled. Moreover, dielectric refers to an electrical insulator that can restrict vibrations of an applied electric field. What occurs is the insulation of an electric current, not allowing electric charges to flow through the material.

Brought to you by ACS Photonics and Wikipedia.com

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