Download wideband EO polymers..

Electro-optic polymers for wideband THz-applications
Alexander Sinyukov, Peter Lindahl, Joey French, and L. Michael Hayden,
Department of Physics, University of Maryland, Baltimore County, Baltimore, MD 21250
Meng He and Robert J. Twieg, Department of Chemistry, Kent State University, Kent, OH 44242
Materials
Optical rectification
Electro-optic polymer composites are fabricated
from mixtures of nonlinear optical chromophore
guests and polymer hosts (PMMA, APC).
N
Lemke-e
 P (t)
ETHz (t,) ~
2
t
2
Eopt (t, )

N
m =8.31 Debye,  =12165 esu
EO polymer properties
(2)
NL
0
P ()   (;  ,   )E( )E( )
NL
(2)
Wideband, sub-ps visible light generates far-IR femtosecond
pulses via three wave mixing amongst the input frequencies.
• high electro-optic coefficient
(r33 = 50 pm/V @ 785 nm)
no phonon absorption !!
phase matching ??
n = 1.75 @ 800 nm, static
dielectric constant, e ~ 3
50-500 mm thick

versatility
• cheap !
N
Electro-optic detection
Predicted frequency response
O
DCDHF-MOE-V
m = 12.3 Debye,  = 18576 esu.
m/M = 1.9 x Lemke
NC
CN
 phonon absorption gaps in ZnTe, GaP response
 very thin crystals required for wideband response
 no resonances in polymer composites
 coherence length tuning possible in polymers
 polymers have larger response (rpolymer > rcrystal)
THz beam
pellicle
N
CN
[110]
O
O
polymer
[1-10]
polarizer
(2) material
CN
CN
ik ( 0 ,)


e
1
(2)

f ()  Copt() eff (; 0 , 0  )

ik ( 0 ,) 

compensator
CN
polarizer
O
N
DCDHF-6-V
ZnTe
m = 12.7 Debye,  = 18640 esu
m/M = 1.7 x Lemke
ZnTe
n lr41

ETHz

3
polymer 
2n lr33 sin 
2
2
3 n  sin 
2
2
ETHz
The THz beam provides the electric field which
modulates the index of refraction in the (2) material.
Balanced detection increases the signal-to-noise ratio.
lc 

k

c
dnopt
 THz nopt   opt
d
 nTHz
o p t
film
ITO
THz-performance of EO polymer
Experimental setup
1 cm
glass
polarizer
Laser
180 fs, 795 nm,
250 KHz, 1 W
Variable
delay st age
Off-axis
paraboloid
T Hz
P ellicle
EO
emit ter
EO
sensor
T eflon
(blocks 800 nm,
passes T Hz beam)
/4-plate
polarizer
Lock-in
Balanced det ectors
13 mm thick scaling
Wideband emission