A reference written in the time convention states that a dye-doped polymer film has…
PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Wave propagation and light in media · Wave propagation and light in media
What an Instrument Can See, Ch The optical constants of a medium
Problem
A reference written in the e+iωt time convention states that a dye-doped polymer film has complex refractive index n~=1.55−0.0032i at 590 nm, with absorption represented in that convention by a negative imaginary part. Someone transcribes this directly into the e−iωt convention (the one used here, where κ>0 means absorption) and writes: "n~=n+iκ=1.55−0.0032i, so κ=−0.0032. Since κ is negative, in this convention the film has gain, not loss."
((a)) Find the error in this reasoning.
((b)) Give the correct value of κ in the e−iωt convention and the corresponding absorption coefficient α at 590 nm.