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Nick N. Lepeshkin, Aaron Schweinsberg,Ryan S. Bennink, Robert W. Boyd
The Institute of Optics, University of Rochester, Rochester, NY 14627, USA
Robert L. Nelson
Air Force Research Laboratory, (AFRL/MLPO) Wright-Patterson Air Force Base, Ohio 45433-7707 and
Enhanced Nonlinear Optical Response of 1-D Metal-Dielectric Photonic Band-Gap Structures
and
Presented at the Optical Society of America Annual Meeting, Orlando, Florida, October 2, 2002
How to Access Optical Nonlinearity of Metals?
opaque! -esu 1010 78)3( -- - @metalcesu 10 14)3(
2
-@SiOc - transparent!
• colloidal solutions • metal doped glasses• granular metal films
Discontinuous composite materials:
Layered periodic MD structures:
High transparency within specified spectral range (PBG effect) Enhanced NLO response
E
z
SiO2 Cu
L0
E
z
Cu
R.S. Bennink, Y.K. Yoon, R.W. Boyd, and J. E. Sipe Opt. Lett. 24, 1416, 1999.
• Metals have very large optical nonlinearities but low transmission.
• Solution: construct metal-dielectric PBG structure. (linear properties studied earlier by Bloemer and Scalora)
pure metal80 nm of copperT= 0.3%
PBG structure80 nm of Cu (total)T= 10%
• Low transmission is because metals are highly reflecting (not because they are absorbing!).
Accessing the Optical Nonlinearity of Metals with Metal-Dielectric PBG Structures
Accessing the Optical Nonlinearity of Metals with Metal-Dielectric PBG Structures
50 100 150 2000
0.1
0.2
0.3
0.4
0.5
0.6
Silica layer thickness (nm)
T simple modelexact solution
50 100 150 2000
10
20
30
40
50
Silica layer thickness (nm)
|Df p
bg/D
f bul
k|
• Metal-dielectric structures can have high transmission.
Enhancement of NL phase shift over bulk metal
Linear transmission of PBG sample at l = 650 nm.
Copper layers 16 nm thick
• And produce enhanced nonlinear phase shifts!
1-D Metal/Dielectric PBG structures
3
80 nm Cu film
1
2
40/389 nm Cu/SiO2 FP
3
5 x 16/98 nm Cu/SiO2 PBG
2%
22%
50%0
0.2
0.4
0.6
500 600 700 800
Wav el ength, nm
21
Linear Optical Properties
0
0.05
0.10
0.15
0.20
0.25
400 500 600 700 800 900
Wavelength, nm
Transmittance
Bulk: 40 nm Cu film PBG: 5 x 16/98 nm Cu/SiO
Bulk
PBG
0
0.2
0.4
0.6
0.8
1.0
500 550 600 650 700
A
R
T0.1
0.3
0.5
0.7
500 550 600 650 700
A
T R
Bulk
PBG
0.5
1.0
1.5
2.0
2.5
500 550 600 650 7000
1
2
3
4
5
500 550 600 650 700
Re(F)
Im(F)
Wavelength, nmWavelength, nm
Model of Enhanced Nonlinear Optical Response
intensity enhancement factor I
Phase sensitivity factor F
e e cª +lin m I F E( )3 2 m,pbg
m,bulk=I
E
E
2
2 p2l
f=
ÚF
n dz
D
Dwhere
I = intensity enhancement factorF = phase enhancement factor
I and F calculated numerically for our five layer design
550 560 570 580 590 600 610 620 630 640 6500
2.108
4.108
Fermi smearingZ-scan data
Wavelength, nm
-
550 560 570 580 590 600 610 620 630 640 6500
2.108
4.108
Fermi smearingZ-scan data
Wavelength, nm
-
0
4¥10 8 Z-scan data
Fermi smearing model
580 600 620 640560
2¥10
Nonlinear Susceptibility of Bulk Copper
8
Im c(3)
wavelength, nm
• Near interband threshold, Fermi smearing is dominant nonlinear process
• We find Im c(3) >> Re c(3) at all wavelengths where response is measurable
• Width of resonance is approximately 4 kT(Hache et al., Appl. Phys. A 47, 347-357 (1988))
Z-Scan Comparison of M/D PBG and Bulk Sample
35 @¢¢
¢¢
Cu
PBG
fdfd
0.50
0.75
1.00
0 50 100 150 200 250
z,mm
Tnorm
Cu
PBG
l = 640 nm
I = 500 MW/cm2Open-aperture Z-scan
(measures Im c(3))
Spectral Dependence of the Nonlinear Response
0
0.5
1.0
1.5
2.0
500 550 600 650 700
PBG
Bulk
wavelength, nm
Im f
NL
OPG:
Q = 2 to 5 mJ
I @ 100 MW/cm2
t = 25 ps
Conclusions
We experimentally demonstrated enhanced nonlinearresponse of 1 -D MD PBG structure. The enhancement factor was measured to be as high as 35.
We produced a stable, artificial, solid-state NLO materialwith a tunable transmission band and high damagethreshold.
