Exact Analysis of Optical Precursor in Lossless Plasma

Abstract:

When an electromagnetic field propagates through a linear but dispersive medium, the front edge (the launching fringe of the waveform where the field is first turned on) propagates precisely at the speed of light in vacuum by first timing on t₁=t_front =（z/c）and the main signal (the main part of the field) follows up with group velocity which is characterized by the frequency-dependent refractive index of medium by second timing on t₂=t_group=(z/v_group)=[n(φ)z/c] .The distinct wave-packets progress from t_front to t_group (i.e. from the front-edge-timing to the main-signal-starting timing) are well known as optical precursors. It was believed that precursors are an ultra-fast phenomena, persisting only for a few optical cycles, and that they have an exceedingly small amplitude and two different kinds of spike-type wave-packet (i.e. Sommerfeld precursor and Brillouin forerunner). Both exact wave shape for electromagnetic wave while it goes into a linear time-invariant, lossless plasma system is reported.

• Periodical: Applied Mechanics and Materials (Volumes 543-547)
• Pages: 405-409
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.543-547.405
• Online since: March 2014
• Authors: Teh Chau Liau*, Jian Qi Shen, Yao Huang Kao, Tzong Jer Yang
• Keywords: Brillouin Forerunner, Optical Precursor, Sommerfeld Precursor

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