16
/
QELS
2001
/
MONDAY
MORNING
Ene gy
(eV)
0.8
1.2
1.6 0.8
1.2
1.6
Re a dance
A
(A)
QME3 Fig.
2.
(a)
THG
in ensi y
13mm
and
(open and illed ci cles) as a unc ion o el-
lip ici y o he inciden pho ons. F om his one
ob ains (b) he phase di e ence and (c) he am-
pli ude a io o he unde lying independen ele-
men s
o~x'').
nonze o componen s a e
x'2
=
K=
ei'oxx
and
x'&
=
'cXY
e'+q
o he applicable 4/mmm sym-
me y.
As
shown in Fig. 2a, we measu e he co e-
sponding THG in ensi ies
I2
and
1:
as a unc-
ion o ellip ici y o he inciden pulses
( e a dance
A
away om linea pola iza ion).
F om his, one ob ains he phase di e ence
6
=
9,
-
9,
and ampli ude a io
p
=
".pa.
These
alues shown in Figs. 2(b,c) exhibi s ep-like
changes concu en wi h he appea ance o he
esonance (Fig.
1).
The esonance hus a ec s di -
e en ly he p oduc s o ma ix elemen s pa allel
o he same
axis,
~(2,
and he mixed p oduc s,
x(&,,
implying a leas a signi ican con ibu ion
o a pa i y o bidden ansi ion ac i e a
2w.
Fu -
he mo e, i can be shown ha
lzXy
=
0
occu s
only o
p
=
3,
a alue associa ed wi h an o e all
sphe ical elec onic dis ibu ion.
As
shown in Fig.
2,
while
p
=
3
a
he esonance, he ansi ion
h ough he esonance
is
associa ed wi h a change
o symme y o he THG enso . Mo e de ailed
calcula ions a e unde way o link hese no el e-
sul s o he symme ies o he unde lying wa e-
unc ions in he S ,CuO,CI, bands uc u e.
Re e ences
1.
2.
3.
M.Z.
Hasan, e al. Science
288,
1811 (2000).
Y.Y.
Wang, e
al.
Phys. Re . Le . 77, 1809
(1996).
H. Kishida, e al. Na u e 405,929
(2000).
~~~~~
Nonlocal e ec s in he nonlinea op lcal
esponse o chi al molecules: Thi d-o de
nonllnea ci cula dich oism
H.
Mesnil,
M.
C. Schanne-Klein and
E
Hache,
Op ical Bioscience Labo a o y Ecole
Poly echnique F-91128 Palaiseau-F ance;
E nail:
[email p o ec ed]
Al hough i was p edic ed as soon as 1967,' hi d-
o de nonlinea ci cula dich oism has ne e
been expe imen ally obse ed. In his pape , we
in es iga e his phenomenon in a liquid o chi al
molecules. We i s pe o m a heo e ical calcula-
ion including nonlocal e ec s in he nonlinea
ligh -ma e in e ac ion ha allows o ge insigh
in o he p ocess and o ob ain i s o de
o
magni-
ude? We hen demons a e expe imen ally he
exis ence
o
such a hi d-o de nonlinea ci cula
dich oism wi h a
Ru henium- is(bipy idy1)
sal
ha we ha e unde i s
wo
enan iome ic
(A
and
A)
o ms. Se e al expe imen s a e ca ied ou
wi h a 1 kHz, 180 s lase sou ce: a one beam sa -
u a ion expe imen whe e a sa u a ion o he ci -
cula dich oism is clea ly obse ed3 and a pump-
p obe expe imen . In he la e case, by
modula ing he pola iza ion o he p obe
o
o
he pump om a le o a igh ci cula one, we
obse e an in ensi y-dependen ci cula dich o-
ism
( ig.
1). All hese expe imen s a e shown o
de i e om he same nonlinea mechanism,
namely a chi al signa u e in he op ical Ke e -
ec . We u he mo e show ha ou esul s a e in
good ag eemen wi h
ou
heo e ical calcula ion.*
Ex ension o his echnique o ime- esol ed ci -
cula dich oism measu emen is discussed.
1.
S.A.
Akhmano andV.1. Zha iko , JETP Le .
6,137 (1967).
2. F. Hache,
H.
Mesnil and M.C. Schanne-Klein,
Phys. Re .
B
60,6405 (1999).
3.
H. Mesnil and F. Hache, Phys. Re . Le .
85,
4257 (2000).
QME5 1115
am
F equencydoubllng o em osecond
pulses in walk-o compensa ed
N-(
4ni ophenyl)-L-p olinol
Juan P. To es, Sil ia Ca asco and Lluis To ne ,
Lab. o Pho onics, Poly echnic
Uni .
o ca alonia,
UPC 03, Ba celona 08034, Spain
E ic W. VanS yland,
CREOL,
Uni e si y
o
Cen al Flo ida, O lando, Flo ida 32826,
USA
N-(4-ni ophenyl)-L-p olinol
(NPP) is an o -
ganic molecula c ys al de elopped by molecula
I
.8
.
I
.6
1
.4
I
.I
I
.o
0.8
0.6
0.4
0.2
0
.O
.0.2
-0.4
-0.6
.0.8
.I
.o
-1.2
Ill,
QME4 1100
am
-0.8
0.0
0.2
0.4
0.6
0.8
1.0
111,
QME4 Fig.
1.
Pump induced ci cula dich o-
ism
o
a pola iza ion-modula ed pump (a) o
p obe (b) s pump in ensi y. Squa es and do s:
A
and
A
enan iome s, iangles: acemic mix u e.
enginee ing,' ha exhibi s one o he highes
phase-ma chable second-o de suscep ibili ies
epo ed
so
a in he nea -in a ed spec al ange
(deE
=
56 pm/V). Howe e , he la ge spa ial and
empo al walk-o exis ing in NPP can limi se-
e ely he use ulness o he ma e ial away om
he nonc i ical phase-ma ching (ncpm) wa e-
leng h and
o
sho e pulses.2
He e we show ha subpicosecond pulses can
be e icien ly equency-doubled and mixed in
NPP wi h mode a e pump in ensi ies, by employ-
ing il ed pulse echniques.' which makes use o
he la ge Poyn ing ec o walk-o exhibi ed by
NPP c ys als ou side he ncpm. Such echniques
a e based on he di ac ion o he inpu pump
wa e by a g a ing
so
ha each spec al compo-
nen is dispe sed in a di e en di ec ion, hus he
esul ing signal is a il ed pulse. When he beam
wid h o he inciden signal on he g a ing is la ge
(i.e., a ew mm), he e ec o di ac ion can be
accoun ed o by conside ing empo al e olu ion
only bu wi h new e ec i e in e se g oup eloci-
ies
u
=
k',
+
an(y ) an(p )/c and g oup- eloc-
i y dispe sions
g,
=
V'"
-
( an(V)/c)'/k,,. He e,
is
he il angle,
c
is he eloci y o ligh in acuum,
k,
a e he linea wa enumbe s,
k',
a e he in e se
g oup eloci ies,
IC',
a e he g oup eloci y dispe -
sion
(GVD)
and
p
a e he Poyn ing- ec o wak-
o angles.
We p oceed as ollows. Fi s , we calcula e he
phase-ma ching angle
€Ip n
a he pump wa e-
leng h using he app op ia e Sellmeie equa ions.
Second, we ind he alue o he il
y ,,
equi ed
o g oup eloci y misma ch (GVM) cancela ion
(U'
=
u2).
All
his hen gi es he e ec i e GVDs,
g,,.
Figu e 1 shows ha a il -accep ance o se e al
deg ees is ob ained wi h walk-o leng hs in ex-
cess o 5 mm. Simila ly, o a ixed il a wa e-
-1
I
E
6-
4
II
II
SH
I
.
-,-
-
-
-
10 20
30
40
Til
(deg ees)
0
-----
~
1.5 1.55 1.6 1.65 1.7
Wa eleng h@ n)
QME5 Fig.
1.
In (a): E ec i e dispe sion
leng hs,
L,,
a he undamen al (FF) and second-
ha monic (SH) equencies (solid lines), and
empo al walk-o leng h,
L,,
(dashed lines), as a
unc ion o he il angle o a ixed pump wa e-
leng h
h
=
1.6 pm. In (b): Dispe sion and walk-
o
leng hs as
a
unc ion
o
pump wa eleng h o
a ixed il angle
y o
=
24.9'. In bo h cases:
€I
=
€Ipm,
T
=
100 s ( ull wid h hal maximum a in ensi y).
MONDAY
MORNING
/
QELS2001
/
17
P.
A echnique o de e mining o a ional in a i-
an s
o
p
by means
o
Kleinman disallowed
hype -Rayleigh sca e ing was designed and e-
po ed e~en ly.~ A quan um mechanical sum-
o e -s a es heo y o he molecula hype pola iz-
abili y indica ed ha low-lying s a es wi h
ansi ion dipole momen s pe pendicula o he
molecule axis (i.e. B-s a es) a e esponsible o
nonze o Kleinman-disallowed (including he
second- ank) pa o
p.
Molecules o
C,,
o
simi-
la symme y a e common in o ganic nonlinea
op ics as hey do no ha e he in e sion cen e (a
majo equi emen o NLO ma e ials), and hey
also o en ha e a la ge pe manen dipole momen
ha made hem sui able o elec ic ield poled
ma e ials. On he o he hand, his symme y al-
lows he exis ence o elec onic s a es ha a e odd
wi h espec o wo- old o a ion (co esponding
o B- ep esen a ions), which, in u n, esul s in a
second- ank enso con ibu ion o
p.
Ea ly s ud-
ies showed ha A-shaped ch omopho es, i.e.
hose ha ing an elec on accep o (dono ) con-
nec ed o wo dono (accep o ) g oups wi h
n-
conjuga ed b idges o o m a
A
shape, may be o
in e es as hey may ha e a la ge second- ank
componen o
p
ha can be employed in align-
men schemes as men ioned abo e. He e we p es-
en sys ema ic measu emen s o he o a ional in-
a ian igu es o me i o se e al A-shaped
ch omopho es (Figu e
1).
Table 1 summa izes
he da a o he s udied ma e ials. One can no ice
ha he igu e o me i o he second- ank com-
ponen o all ma e ials eaches, and in some
E-
=*'
*-
=
m
QME5
Fig.
2.
De ailed e olu ion o he
SH
pulse. (a): Wi h GVM compensa ion; (b): wi h-
ou GVM compensa ion. Condi ions:
h
=
1.6
pm,
8
=
epm,
7
=
100
s,
I,,
=
10
MW/cmZ (peak in en-
si y) and
a,,
=
3
mm (beam wais ). No
SH
pulse
a he impu .
leng h bandwid h o se e al ens o nanome e s is
ob ained. Figu e
2
shows he de ailed
SH
pulse
e olu ion whe he he e is walk-o compensa-
ion
o
no , by sol ing nume ically he e olu ion
equa ions. The di e ence is clea ly isible: while
wi hou walk-o compensa ion
no
use ul sec-
ond-ha monic
(SH)
is gene a ed, a clean, na ow
high in ensi y
SH
pulse is ob ained wi h he il ed
pulse. Losses would educe he e iciency o e-
quency doubling in hick c ys als, bu a high
quali y ou pu second ha monic pulse is always
ob ained.
In conclusion, we p edic ha highly e icien
equency doubling o subpicosecond pulses can
be accomplished in walk-o compensa ed NPP
wi h peak pump in ensi ies in he MW/cm2
ange, in a wide wa eleng h band cen e ed
a ound he hi d elecommunica ion window.
Resul s a e belie ed o g ea ly expand he po en-
ial applica ions o NPP o he implemen a ion o
pa ame ic de ices and cascading phenomena in
gene al.
Re e ences
1.
2.
7.
Zyss,
J.F.
Nicoud, and M. Coquillay,
J.
Chem. Phys.
81,4160 (1984).
2. Wang e al.,
J.
Op . Soc.
Am.
B
14, 76
(1997);
G.P.
Ban i a al., Op . Le .
23,
439
(1998).
V.D.Voloso e al., So .
J.
Quan um Elec on.
4, 1090 (1975);
G.
Szabo and 2s. Bo , Appl.
Phys.
58,237
(1994).;
R. Danielius e al., Op .
Le .
21,973 (1996).
3.
QME6
W30
am
Op imiza ion
o
A-shaped molecules o
second ha monic gene a ion in media wi h
nonpola alignmen
V. Os o e kho , R. G. Pe schek,
K.
D.
Singe ,
Depa men
o
Physics, Case Wes e n Rese e
Uni e si y, Cle eland, Ohio, USA;
Email: [email p o ec ed]
M. He and R.
I,
Twieg,
Depa men
o
Chemis y,
Ken S a e Uni e si y, Ken , Ohio, USA
Conside able e o has been di ec ed owa ds
c ea ing o ganic nonlinea ma e ials o second
ha monic gene a ion elec o-op ic con ol ha
would implemen he non- ec o i educible
componen s o he i s hype pola izabili y en-
so .',' In pa icula , he second- ank enso com-
ponen can gi e ise o mac oscopic nonlinea i y
x(')
in sys ems ha ing chi al nonpola symme y
o he bulk, such as
0,
o
D2.
These ypes o
alignmen can be achie ed in uniaxially o biaxi-
ally s e ched chi al polyme s,
o
in a ious uni-
axial
(N,
SmA)
and biaxial
(SmC)
liquid c ys al
phases. To make an e icien equency con e -
sion ma e ial, one has o op imize bo h he mo-
lecula esponse o he ac i e ch omopho e and
he mac oscopic alignmen scheme.
The mic oscopic aspec o he p oblem is ad-
d essed by he quan um mechanical heo y o he
i s hype pola izabili y combined wi h measu e-
men s o he o a ionally in a ian igu es o
me i o he ele an i educible componen s o
RT9090 (480nm)
c :
(588Nn)
MG:
(615nm)
BG:
(625~11)
1955-49 (498nm)
QME6 Fig.
1.
Molecula s uc u es and maximum abso p ion wa eleng hs o s udies ma e ials.
QME6
Table
1.
Ro a ional in a ian o measu ed A-shaped ch omopho es
Ma e ial
(h,
nm)
I
I
PISS
I
I
I
I
PImm
I
I I I
Pzmm
I
I I I
P ss
I
I
(esu
X~O-~~)
pNA ( e e ence)
c
MG
BG
pNA ( e e ence)
RT9090
1955-49
pNA ( e e ence)
c
pNA ( e e ence)
c
MG
BG
RT9090
1955-49
1560
nm
7.12
2
0.16
83.5
2.1
69.8
1.8
92.7
2.1
1340 8.09
2
0.09
266.8
2
5.5
316.0
2
9.4
1064 11.2
1.6
305
I
58
780
nm
56.4
I
5.9
552
42
122
10
1422 11
278
2
21
289
22
0.0
2.1
72.2
2
2.1
14
30
24
24
3.0
I
2.6
84.1
6.5
38.6
9.5
57.6
I
6.1
0.0
2.4 3.6
2
1.1
15 I41 128.8
4.9
0
98
4.6
1.2
341
72
2
I
18
162
I
18
186
16
112
27
119
25
180
35
2.1
2.6
276
52
23.4
I
3.8
353
34 309
36
120
I
13
136
2
12
135
I
19
167
16
~~
4.95
0.23
76.0
4.2
54.0
5.0
68.0
3.2
5.40
2
0.19
201.4
4.6
215
2
11
8.2
1.2
398
81
38.3
-
4.1
287
31
131
2
14
153
13
198
16
200
16