Open AccessFast Light and the Speed of Information Transfer in the Presence of Detector Noise
Author(s) -
Michael Z. Feng,
Wayne V. Sorin,
Rodney S. Tucker
Publication year - 2009
Publication title -
ieee photonics journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 73
eISSN - 1943-0655
pISSN - 1943-0647
DOI - 10.1109/jphot.2009.2031684
Subject(s) - engineered materials, dielectrics and plasmas , photonics and electrooptics
The phenomenon of fast-light pulse propagation has seen renewed interest in recent years, but its relationship to the speed of information transfer is still being debated. In this paper, we define the speed of information transfer as the propagation speed of a point of constant signal-to-noise ratio (SNR) on the leading edge of a signal pulse. We use standard telecommunication analysis to include the effects of noise so that the bit-error rate (BER) can be calculated as a function of a variable decision time. We introduce the concept of a time-dependent Q-factor so that pulse arrival times can be compared at equivalent BERs. We show that when receiver noise is included in a gain-assisted fast-light system, the measured speed of information transfer can exceed the speed of light for an equivalent pulse travelling through a vacuum.