A Fabry-Perot etalon uses two identical silver mirrors facing an air spacer ( ) of…

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Wave propagation and light in media · Interference and diffraction

What an Instrument Can See, Ch Multiple beams: the stack as a matrix and the etalon as a filter

Problem

A Fabry-Perot etalon uses two identical silver mirrors facing an air spacer (

n=1

) of thickness

d = 2.00\,\text{mm}

, at normal incidence and at

\lambda_0 = 633\,\text{nm}

, where silver has complex refractive index

\tilde n = 0.14 + 3.98i

. ((a)) Use the Fresnel amplitude reflection coefficient for the air-metal boundary to find the mirror power reflectance

R

. ((b)) Hence find the finesse

\mathcal F

that these mirrors alone allow. ((c)) Find the free spectral range and the linewidth of this etalon. Take

c = 3.00\times10^8\,\text{m s}^{-1}