An ADP crystal ( , ) is cut for transverse operation at

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Polarisation and anisotropic media · Polarisation and anisotropic media

What an Instrument Can See, Ch Modulating light: electro-optic, acousto-optic and magneto-optic devices

Problem

An ADP crystal (

n_o = 1.52

r_{63} = 8.5\,\mathrm{pm\,V^{-1}}

) is cut for transverse operation at

\lambda_0 = 632.8\,\mathrm{nm}

. The field is applied along the optic axis across an electrode gap

d = 2.0\,\mathrm{mm}

, and the light travels along

x'

, at 45 degrees to

x

and

y

, through an interaction length

L = 25\,\mathrm{mm}

. A compensating crystal cancels the natural birefringence, so only the field-driven retardance remains. ((a)) Find the half-wave voltage

V_\pi

of this transverse cell. ((b)) Find the voltage needed for a quarter-wave retardance (

\Gamma = \pi/2