An international team of researchers has proven that silicon nanoparticles can increase the intensity of the Raman Effect by a large margin. The result of this discovery could alter the way in which nanoscale light emitters and nanoscale amplifiers are used in fiber optic telecommunications; this, in turn, could lead to change within the industry in a very big way.
The Raman Effect refers to the scattering of light when it interacts with certain materials; the result is longer or shorter wavelengths, as well as different colors. This occurs because the light causes the molecule it’s interacting with to increase its energy in an amount equivalent to the vibration of the molecule itself. This new energy, if you will, that the molecule is experiencing, causes it to re-emit a photon that has a smaller amount of energy than the incident photon, but a longer wavelength and red color.
The Effect itself is well established — it’s already leveraged in fiber optic telecom technologies for the purpose of boosting signals travelling through long stretches of glass fiber. Raman scattering is also used to transfer light from a strong pump beam into a weaker data beam, while Raman amplification is responsible for enabling most long-distance telephone calls today.
Typically speaking, metallic nanoparticles are used for the purpose of inducing the Raman Effect, but in this latest research, researchers from the Moscow Institute of Physics and Technology (MIPT), ITMO University (St Petersburg), and the Australian National University made the decision to try silicon nanospheres instead; specifically, Mie resonances, which support optical resonances.
For those unfamiliar, resonant wavelengths depend on the size of the particle — the largest size (referred to as magnetic dipole resonance) is generally comparable to the diameter of the particle.
In this new research, the team discovered that the silicon’s refractive index (how light transmits through a medium) is so large that its magnetic dipole resonance is recorded in wavelengths longer than 300 nanometers, even though the diameter of the particle is just 100 nanometers. In terms of recording, the researchers found that when light hit a resonant particle, it produced a Raman emission intensity 100 times greater than non-resonant particles.
What’s more, these smaller silicon nanoparticles have also provens they can be used to create other forms of enhanced optical phenomena, like spontaneous light emission and enhanced light absorption.
“The Raman effect is incredibly useful in practice, and will help not only in detecting microscopic amounts of chemical compounds,” said Denis Baranov, a post-graduate student of MIPT and one of the authors of the paper, in a press release, “but [will also be useful for] transmitting information over long distances.”
Baranov adds that because electronics and optical devices continue to shrink, the need for nanostructures that have outsized Raman effects is extremely important. “Our observations have revealed a potential candidate – silicon nanoparticles,” says Baranov.
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