A KDP-type (class ) electro-optic crystal has ordinary index and effective contracted…

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

A KDP-type (class

\bar42m

) electro-optic crystal has ordinary index

n_o = 1.50

and effective contracted coefficient

r_{63} = 11\,\mathrm{pm\,V^{-1}}

, and is used at

\lambda_0 = 550\,\mathrm{nm}

. ((a)) Compute the half-wave voltage

V_\pi

for a longitudinal cell (field along the light path). ((b)) The same crystal is now cut for transverse operation: the field is still along

z

, applied across an electrode gap

d = 1.0\,\mathrm{mm}

, and the light travels along

x'

, at 45 degrees to

x

and

y

, through an interaction length

L = 20\,\mathrm{mm}

. Taking the natural birefringence as cancelled by a compensating crystal, compute

V_\pi

for this geometry.