Effect of the surface integral in the torque equation of the electromagnetic angular momentum on the Faraday rotation

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• 作者：Osamu Yamashita^a ; ^{yamashio567@yahoo.co.jp"" rel=""nofollow}
• 关键词：Electromagnetic angular momentum ; Torque equation ; Faraday rotation ; Surface integral ; Volume integral
• 刊名：Optics Communications
• 出版年：2011
• 出版时间：1 September 2011
• 年：2011
• 卷：284
• 期：19
• 页码：4248-4253
• 全文大小：526 K

文摘

A circularly polarized plane wave of infinite transverse extent (δ = ∞) has no spin angular momentum, while a realistic light does carry it. This paradox originates from the presence (δ = ∞) and absence (δ ≈ 0) of the surface integral in the total angular momentum J. The same holds for the torque equation of dJ/dt, so that δ is also connected with the relative Faraday rotation angle Θ_F/θ_F when a radius (a) of a cylindrical medium with optical activity is only a little larger than that (b) of light beam, where Θ_F is the Faraday rotation angle and θ_F is the intrinsic Faraday rotation angle of a medium. It is shown here that it is possible to estimate δ for a realistic light from the drastic variation in Θ_F/θ_F near b/a = 1.