Lecture 1: Foundations of Optics Outline 1 Electromagnetic Waves 2 Material Properties 3 Electromagnetic Waves Across Interfaces 4 Fresnel Equations Christoph U. Keller, Leiden University,
[email protected] Lecture 1: Foundations of Optics 1 Electromagnetic Waves Electromagnetic Waves in Matter Maxwell’s equations ) electromagnetic waves optics: interaction of electromagnetic waves with matter as described by material equations polarization of electromagnetic waves are integral part of optics Maxwell’s Equations in Matter Symbols D~ electric displacement r · D~ = 4πρ ρ electric charge density ~ 1 @D~ 4π H magnetic field r × H~ − = ~j c @t c c speed of light in vacuum ~j electric current density 1 @B~ r × E~ + = 0 E~ electric field c @t B~ magnetic induction r · B~ = 0 t time Christoph U. Keller, Leiden University,
[email protected] Lecture 1: Foundations of Optics 2 Linear Material Equations Symbols dielectric constant D~ = E~ µ magnetic permeability B~ = µH~ σ electrical conductivity ~j = σE~ Isotropic and Anisotropic Media isotropic media: and µ are scalars anisotropic media: and µ are tensors of rank 2 isotropy of medium broken by anisotropy of material itself (e.g. crystals) external fields (e.g. Kerr effect) mechanical deformation (e.g. stress birefringence) assumption of isotropy may depend on wavelength (e.g. CaF2 for semiconductor manufacturing) Christoph U. Keller, Leiden University,
[email protected] Lecture 1: Foundations of Optics 3 Wave Equation in Matter static, homogeneous medium with no net charges: ρ = 0 for most materials: µ = 1 combine Maxwell, material equations ) differential equations for damped (vector) wave µ @2E~ 4πµσ @E~ r2E~ − − = 0 c2 @t2 c2 @t µ @2H~ 4πµσ @H~ r2H~ − − = 0 c2 @t2 c2 @t damping controlled by conductivity σ E~ and H~ are equivalent ) sufficient to consider E~ interaction with matter almost always through E~ but: at interfaces, boundary conditions for H~ are crucial Christoph U.