Slow light now and then

LV Ya-li

Based on classic concept of light,a very useful new concept in communications is given-slow light.Introduced the principle of slow light,main methods have been adopted by researchers around the world,the problems encountered and how to optimize slow light.Meaningwhile,present recent research and develop-ment state of slow light in applications.Finally,the development prospects of slow light is given.

Peter W. Milonni

Ulf Leonhardt

Zhang Shuo

The last decade is of great significance for the development of slow light technology.In order to study on the slow light technology deeply,several kinds of slowing light technologies,such as Electromagnetically Induced Transparency(EIT),Coherent Population Oscillation(CPO),Stimulated Brillouin Scattering(SBS) and photonic crystal waveguide,were contrasted and analyzed.Also some important theoretical and technical developments to improve performance of slow light in last decade were introduced,and then problems and shortcomings existing in slowing technology were discussed.Finally,this paper focuses on some novel technologies of slowing down light velocity and their primary applications.Moreover,it forecasts the future developing trends of slow light and its potential applications.Through research on slow light,results show that slow light will realize more and more significant application values in the field of optical fiber sensing and other fields.

Joseph E. Vornehm

Slow light is light that travels at unusual, extreme group velocities—sometimes as slow as walking speed or slower. Light waves can be described by many velocities, but for a narrow-band pulse of light (a carrier frequency modulated by an envelope), the group velocity is the speed of the pulse envelope. The term slow light also encompasses other exotic group velocities due to similar techniques, including fast light, stopped light, and backwards light. The science of slow light has been established over the past several years, and research attention is now turning to potential applications of slow light. One application of slow light is as an all-optical true-time delay. Two slow light methods in optical fibers, stimulated Brillouin scattering (SBS) and dispersive delay, are used to provide a controllable pulse delay in a prototype slow-light phased-array laser radar, called SLIDAR. These slow light methods compensate the group delay mismatch of pulses of 6 ns duration while the phased array is steered in two dimensions. A phase control system is described that maintains phase lock among three signal channels and a reference channel, each containing 2.2 km of optical fiber, while accommodating the demands of the slow light techniques. Residual phase error is kept below π /5 radians (1/10 wave) RMS. Slow light can also enhance the spectral sensitivity of spectrometers and interferometers. A design for a slow-light-enhanced nanophotonic spectrometer is presented. One important use of spectrometers is to detect specific chemicals, and I describe an approach to multivariate optical computation, which can be used for automatic chemical spectrum recognition. This technique, which could one day be implemented with a slow-light-enhanced spectrometer as a single-chip chemical detection platform, is explored experimentally in the visible spectrum using a spatial light modulator.