A beam of sodium light ( ) travels inside a glass prism of index and strikes the…

PHYSICS · Multi-part · Fermi University Physics · Oscillations, Waves & Acoustics · Optics & Photonics · Wave propagation and light in media

What an Instrument Can See, Ch The boundary as a two-port

Problem

A beam of sodium light (

\lambda_0 = 589\ \text{nm}

) travels inside a glass prism of index

n = 1.50

and strikes the glass-air back face at

\theta = 70.0{}^\circ

from the normal, well beyond the critical angle. Treat the interface as a plane and the reflection as total. ((a)) Estimate the

1/e

(amplitude) penetration depth

d_p

of the evanescent field into the air beyond the face. ((b)) Estimate the lateral (Goos-Hanchen) shift

D_s

of the s-polarised beam along the face, using the fact that this shift follows from the derivative of the s-reflection phase with respect to angle.