Lorentz Oscillator Model for Refractive Index
Lorentz Oscillator Model for Refractive Index
The index of refraction is often described as an apparent decrease in the speed of light from to as it passes through a dielectric medium. In fact, light photons do not actually slow down, but the effect is simulated by a retarding phase shift in the emerging electromagnetic waves. This is caused by superposition of the incident wave with a retarded wave produced by radiation from the electrons in the medium.
n
c
c/n
This Demonstration describes a highly idealized and simplified classical atomic model for the refractive index. Using the sliders, you can vary the wavelength of the incident light, , over the visible region 400–700 nm. You can also vary the natural frequency of the electron oscillators, =2πc/, which generally lies in the ultraviolet, and , the number of oscillating electrons per unit volume. The lower half of the graphic shows the phase retardation of the amplitude for the transmitted radiation compared to the incident radiation. The parameters approximate those of glass, with .
λ=2πc/ω
λ
0
ω
0
N
n≈1.5