Sep 8 2010
Publisher of high-impact scientific and medical information, Nature Photonics has published a study, which reported that a small optical equipment built inside a silicon chip has attained the slowest propagation of light on a chip. Thus the optical device decreased light speed by a factor of 1200.
The electrical engineering professor at the University of California’s Baskin School of Engineering, Holger Schmidt is leading the research team that developed the device. The team also comprises researchers from the Brigham Young University and the UC Santa Cruz.. The optical unit depends on quantum interference effects present in a rubidium vapor, within an optical waveguide. The waveguide is built into a silicon chip by utilizing standard manufacturing methods.
The control laser alters rubidium vapor’s optical properties in the hollow-core waveguide. Electrons present in the rubidium atom are changed into a superposition of two quantum modes. The electrons exist in two states simultaneously. One state occurs because of a condition known as electromagnetically induced transparency, which is important for generating slow light.
Various techniques have been utilized to slow down the speed of light and bring it to a halt. However, systems that were based on quantum interference effects needed elaborate lab setups and low temperatures for practical usage. Earlier in 2008, NTT Laboratories researchers in Japan had developed a photonic crystal waveguide that could decrease the light pulses’ speed by a factor of 170. This waveguide has certain benefits, but it can’t generate the quantum effects like the atomic spectroscopy chip developed by the Schmidt-led team.
Source: http://www.soe.ucsc.edu/