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Chiral nanostructures producing near circular polarization Linköping University Post Print
Chiral nanostructures producing near circular
polarization
Roger Magnusson, Ching-Lien Hsiao, Jens Birch, Hans Arwin and Kenneth Järrendahl
Linköping University Post Print
N.B.: When citing this work, cite the original article.
Original Publication:
Roger Magnusson, Ching-Lien Hsiao, Jens Birch, Hans Arwin and Kenneth Järrendahl, Chiral
nanostructures producing near circular polarization, 2014, Optical Materials Express, (4), 7,
1389-1403.
http://dx.doi.org/10.1364/OME.4.001389
Copyright: Optical Society of America
http://www.osa.org/
Postprint available at: Linköping University Electronic Press
http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-109241
Chiral nanostructures producing near
circular polarization
Roger Magnusson,* Ching-Lien Hsiao, Jens Birch, Hans Arwin and
Kenneth Järrendahl
Department of Physics, Chemistry and Biology, Linköping University
SE 581 83, Linköping, Sweden
*[email protected]
Abstract:
Optical properties of chiral nanostructured films made of
Al1−x Inx N using a new growth mechanism — curved-lattice epitaxial
growth — are reported. Using this technique, chiral films with rightand left-handed nanospirals were produced. The chiral properties of the
films, originating mainly from an internal anisotropy and to a lesser extent
from the external helical shape of the nanospirals, give rise to selective
reflection of circular polarization which makes them useful as narrow-band
near-circular polarization reflectors. The chiral nanostructured films reflect
light with high degree of circular polarization in the ultraviolet part of the
spectrum with left- and right-handedness depending on the handedness of
the nanostructures in the films.
© 2014 Optical Society of America
OCIS codes: (160.1585) Chiral media; (160.4236) Nanomaterials; (160.4760) Optical properties; (310.6860) Thin films, optical properties.
References
1. Q. Wu, A. Lakhtakia, and I.J. Hodgkinson, “Circular polarization filters made of chiral sculptured thin films:
experimental and simulation results,” Opt. Eng. 39(7), 1863–1868 (2000).
2. I.J. Hodgkinson, A. Lakhtakia, and Q. Hong Wu, “Experimental realization of sculptured-thin-film polarizationdiscriminatory light-handedness inverters,” Opt. Eng. 39(10), 2831–2834 (2000).
3. G.P. Agrawal and S. Radic, “Phase-shifted fiber Bragg gratings and their application for wavelength demultiplexing,” IEEE Photonics Technol. Lett. 6(8), 995–997 (1994).
4. R.M.A. Azzam, “Chiral thin solid films: Method of deposition and applications,” Appl. Phys. Lett. 61(26), 3118–
3120 (1992).
5. K. Robbie, M.J. Brett, and A. Lakhtakia, “First thin film realization of a helicoidal bianisotropic medium,” J.
Vac. Sci. Technol. A 13(6), 2991–2993 (1995).
6. A. Lakhtakia and R. Messier, Sculptured Thin Films: Nanoengineered Morphology and Optics (SPIE Press,
2004).
7. M. Hawkeye and M.J. Brett, “Glancing angle deposition: Fabrication, properties, and applications of micro- and
nanostructured thin films,” J. Vac. Sci. Technol. A. 25(5), 1317–1335 (2007).
8. K. Kaminska, A. Amassian, L. Martinu, and K. Robbie, “Growth of vacuum evaporated ultraporous silicon
studied with spectroscopic ellipsometry and scanning electron microscopy,” J. Appl. Phys. 97(1), 013511 (2004).
9. G.Z. Radnóczi, T. Seppänen, B. Pécz, L. Hultman, and J. Birch, “Growth of highly curved Al1−x Inx N nanocrystals,” Phys. Status Solidi A. 202(7), R76–R78 (2005).
10. R. Messier, T. Gehrke, C. Frankel, V. C. Venugopal, W. Otano, and A. Lakhtakia, “Engineered sculptured nematic
thin films, ” Journal of Vacuum Science Technology A: Vacuum, Surfaces, and Films, 15(4), 2148–2152, 1997.
11. T. Seppänen, G.Z. Radnóczi, S. Tungasmita, L. Hultman, and J. Birch, “Growth and characterization of epitaxial
wurtzite Al1−x Inx N thin films deposited by UHV reactive dual DC magnetron sputtering,” Mater. Sci. Forum,
433 − 436, 987–990 (2003).
12. D. Schmidt, E. Schubert, and M. Schubert, “Generalized ellipsometry determination of non-reciprocity in chiral
silicon sculptured thin films,” Phys. Status Solidi A. 205(4), 748–751 (2008).
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Received 5 May 2014; revised 12 Jun 2014; accepted 13 Jun 2014; published 19 Jun 2014
1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1389
13. H. Arwin, R. Magnusson, J. Landin, and K. Järrendahl,“Chirality-induced polarization effects in the cuticle of
scarab beetles: 100 years after Michelson, ” Philos. Mag. 92(12), 1583–1599 (2012).
14. R.A. Chipman, “Mueller Matrices” in Handbook of Optics Bass, V.N. Mahajan, E.W. Van Stryland, G. Li, C.A.
MacDonald and C. DeCusatis, eds. (McGraw-Hill, New York 2010).
15. N.G. Parke, Matrix Optics (Massachusetts Institute of Technology, 1948).
16. R. Magnusson, J. Birch, P. Sandström, C-L. Hsiao, H. Arwin, and K. Järrendahl, “Optical
Mueller matrix modeling of chiral films of helicoidal Alx In1−x N nanorods,” Available online,
http://dx.doi.org/10.1016/j.tsf.2014.02.015
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18. E. Collett, Polarized Light: Fundamentals and Applications (Marcel Dekker, 1993).
19. D. Schmidt, A.C. Kjerstad, T. Hofmann, R. Skomski, E. Schubert, and M. Schubert, “Optical, structural, and
magnetic properties of cobalt nanostructure thin films,” J. Appl. Phys. 105(11), 113508 (2009).
20. D. Schmidt, B. Booso, T. Hofmann, E. Schubert, A. Sarangan, and M. Schubert, “Monoclinic optical constants,
birefringence, and dichroism of slanted titanium nanocolumns determined by generalized ellipsometry,” Appl.
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21. I.S. Nerbø, S.L. Roy, M. Foldyna, M. Kildemo, and E. Søndergård, “Characterization of inclined GaSb nanopillars by Mueller matrix ellipsometry,” J. Appl. Phys. 108(1), 014307 (2010).
22. H. Fujiwara, Spectroscopic Ellipsometry: Principles and Applications (John Wiley & Sons, 2007).
23. M. Schubert and C.M. Herzinger, “Ellipsometry on anisotropic materials: Bragg conditions and phonons in
dielectric helical thin films,” Phys. Status Solidi A. 188(4), 1563–1575 (2001).
24. Y.J. Park, K.M.A. Sobahan, and C.K. Hwangbo, “Wideband circular polarization reflector fabricated by glancing
angle deposition,” Opt. Express 16(8), 5186–5192 (2008).
1.
Introduction
The optical properties of chiral sculptured thin films (STF’s) make them well suited for applications such as polarizations filters [1], handedness inverters [2] and bandpass filters used in
optical fiber communication [3], to mention a few. The realization of such chiral films is commonly done by glancing angle deposition (GLAD), a self-shadowing technique for fabricating
thin films with tailored nanostructural properties [4–7]. By using various materials and tailoring the pitch of the nanostructures, chiral STF’s can be engineered to obtain desired optical and
physical properties [6].
However, a known problem with GLAD is the broadening of the columns when the films
grow thicker [8] making films with large pitches a challenge to manufacture. In this study we
have used controlled curved-lattice epitaxial growth (CLEG) [9] to produce nanorods with a
curved, single-crystalline morphology with not only an external chirality (the spiral shape of
each nanocolumn) but also with an internal chirality due to an in-plane compositional gradient.
The compositional gradient results in an in-plane birefringence which rotates throughout the
film with the same nominal period as the external chirality. This method has been employed to
produce chiral thin films with a high thickness to pitch ratio. Our material of choice is the semiconductor Al1−x Inx N, where x can be chosen to tailor the band-gap [11]. With the Al1−x Inx N
material system we have the possibility to fabricate unique structures with tailored polarization properties in both reflection and transmission mode. The aim of this work is to explore
the optical properties in general and specifically the ability to reflect polarized light with high
degree of circular polarization. Mueller-matrix spectroscopic ellipsometry (MMSE) has been
used to determine the optical properties of right- and left-handed chiral nanostructured films as
well as non-chiral nanostructured films. MMSE is a very suitable, non-destructive technique for
investigations of advanced optical materials including the present chiral semiconductor [12,13].
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1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1390
2.
Theory
In the Stokes formalism, the polarization state of light is described by a four-element column
matrix


I
 Q 

(1)
S=
 U 
V
often called a Stokes vector, where, in a Cartesian coordinate system, I = Ix + Iy , Q = Ix − Iy ,
U = I+45◦ − I−45◦ and V = Ir − Il , where Ix and Iy denote irradiance of linear polarization in
the x and y directions, respectively, I+45◦ and I−45◦ denote irradiance of linear polarization in
the +45◦ , and −45◦ directions, respectively and Ir and Il denote irradiance of right- and lefthanded circular polarizations, respectively. I is thus the total irradiance, and Q and U describe
the linear part of the polarization state. The fourth parameter, V , describes the circular part of
the polarization state [14].
The change in polarization as well as the change in degree of polarization of light when it
interacts with a sample is described in the Stokes-Mueller formalism by
So = MSi
(2)
where Si is the Stokes vector of the light incident on the sample, So is the Stokes vector of
the reflected light and M is a 4x4 matrix known as the Mueller matrix [15] which depends
on the properties of the sample [17]. It is common to normalize a Stokes vector to I and a
Mueller matrix to M11 , and in this work we will use this practice for Si and M so that Ii = 1 and
mi j = Mi j /M11 , respectively. With mi j , i, j ∈ [1, 2, 3, 4], Eq. (2) then becomes



 
Io
1
1
m12 m13 m14
 Qo   m21 m22 m23 m24   Qi 



 
(3)
 Uo  =  m31 m32 m33 m34   Ui 
m41 m42 m43 m44
Vi
Vo
Any polarization state can be described by Q, U and V [18]. All linear polarization states, as
well as their azimuth will only affect Q and U whereas circular polarization states affect only V .
When the incident light is unpolarized, i.e. Si = [1, 0, 0, 0]T (T denotes transpose), the reflected
light So will have a Stokes vector equal to the first, normalized, column of the Mueller matrix,
[1, m21 , m31 , m41 ]T = [1, P]T where PT is the polarizance vector [14].
From the Stokes parameters the degree of polarization, P, can be derived and with I = 1 we
define
p
(4)
P = Q2 +U 2 +V 2
We can also define the degree of linear polarization as
p
PL = Q2 +U 2
(5)
and the degree of circular polarization as
PC = V
(6)
where the sign of PC determines the handedness of the polarized light. A positive value corresponds to right-handed polarization, and a negative value corresponds to left-handed polarization. The degree of polarization varies between 0 for completely unpolarized light and 1 for
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1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1391
completely polarized light. For any other value of P the light is partially polarized and it can
then be described as a sum according to
S = (1 − P)Su + PS p
(7)
where superscripts u and p indicate unpolarized and polarized parts, respectively.
3.
3.1.
Experimental details
Sample preparation
Al1−x Inx N nanorod films were fabricated with the CLEG technique using dual magnetron sputter deposition on sapphire substrates with vanadium nitride buffer layers as described in detail
elsewhere [9]. Due to shadowing effects during deposition, the individual nanorods will have
a higher concentration of Al on one side and of In on the other side. Assuming a morphology
similar to that of previous studies [9], x in Al1−x Inx N is estimated to have a mean value of 0.3
and a variation from one side of one nanorod to the other of approximately 18% (∆x ≈ 0.18).
The difference in lattice constants will result in a curving of the nanorods towards the Al rich
side. The difference in refractive index between AlN and InN will also cause a refractive index
gradient across each nanorod. By introducing a rotation of the substrate during deposition this
gradient will rotate with increasing height of the nanorods. The result will be twofold: An internal chirality due to rotation of the refractive index gradient and an external chirality due to the
curved nanorod, which in turn depends on the height gradient of the crystal lattice. All nanorods
will be aligned to each other with respect to both the internal and the external chirality.
This work focuses on films deposited in three ways. Chiral films were grown on substrates
which were rotated 19 times in 90◦ steps during deposition, either clockwise or anti-clockwise
(as seen from the ambient) to produce right- or left-handed films of nanospirals, respectively.
In addition straight nanorod films were grown on substrates rotated continuously with several
turns per deposited monolayer. In the latter case the curving of the nanorods can be neglected,
producing a non-chiral film with straight nanorods.
Thus the chiral films each consist of 20 sublayers with curved nanorods, with each consecutive layer grown at a 90◦ (-90◦ ) angle to the previous layer for left- (right-) handed samples.
The result in each case will be a fourfold stepwise helical staircase structure of five complete
turns. Notice that the samples are similar to the ones presented in [16] which, however are continuously helical and not stepwise helical. Straight nanorods are also analyzed in the current
report.
3.2.
Instrumentation
All optical measurements were done using a dual rotating compensator ellipsometer (J.A.
Woollam Co., Inc). The instrument provides all 16 elements of the Mueller matrix in the spectral range of 245≤ λ ≤1700 nm. The ellipsometer is equipped with a sample holder allowing
for measurements with 360◦ azimuthal sample rotation ϕ, as well as variable incidence angle
θ . In this study ϕ was varied between 0◦ and 360◦ in steps of 5◦ and θ between 20◦ and 65◦
in steps of 5◦ . Only data for λ in the range of 245 nm to 1000 nm are reported. The software
CompleteEASE (J.A. Woollam Co., Inc.) was used to calculate P and PC .
The scanning electron microscopy (SEM) images were taken by a LEO-1550 FE-SEM.
4.
4.1.
Results and discussion
Structural characterization
Figure 1 shows SEM images of films grown using the three growth schemes. The height of
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1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1392
d
a
c
b
Figure 1. Scanning electron microscopy images of a) right-handed nanospirals, b) straight
nanorods and c) left-handed nanospirals. d) Top view of straight nanorods.
the nanorods varies among the samples. The straight nanorods are approximately 640 nm high,
whereas the left-handed are 1100 nm and the right-handed are 1050 nm high. The individual
nanorods are approximately 60 nm in diameter and the spiral diameter is approximately 80 nm.
The curvature of the nanorods is due to the gradient in lattice parameters in Al1−x Inx N described above. This difference in lattice parameter causes the thickness to vary from side to
side in each nanorod so that each monolayer forms a wedge. When the wedges are stacked the
structure will curve towards the Al rich side, as schematically shown in Fig. 2(a), and the angle
b
a
α
Figure 2. Schematic view of a nanorod, curved due to the difference in lattice constant
between the Al-rich (green color) side and the In-rich side (red color). a) A side view of
a nanorod as deposited without substrate rotation. The curvature is strongly exaggerated
and in the real structure the angle α is approximately 1.8◦ . b) One period of a right-handed
four-fold stepwise helical staircase nanospiral where the substrate has been rotated three
times in 90◦ steps.
between two atomic layers 17 nm apart will be 1.5◦ ± 0.5◦ [9]. The first and last atomic layer
of each 20 nm nanorod would then be at an angle (α in Fig. 2(a)) of ∼ 1.8◦ with respect to each
other. This is just enough for the curve of the rods to be noticeable in an SEM image (Fig. 1).
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1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1393
Thus it is not so much the external chirality that gives rise to the optical properties, but rather
the internal chirality of each nanorod that forms a repetitive pattern throughout the height of
the sample [16].
4.2.
Optical characterization
Figure 3 shows PC of light reflected off the three samples if illuminated with unpolarized light
Degree of circular polarization, Pc
a
b
c
Wavelength, λ (nm)
Figure 3. Degree of circular polarization, PC , at 25◦ incidence angle for a) a sample with a
right-handed chiral film, b) a sample with a straight nanorod film and c) for a sample with
a left-handed chiral film. The insets show the shape of the near-circular polarization state
at their respective peak values (solid curves) inscribed in perfect circles (dashed curves).
at θ =25◦ whereas PC for other incident polarization states can be seen in the appendix. There
is no correlation between the starting orientation of the substrate during deposition and the
starting angle (ϕ =0) of the measurements. Therefore, when presenting the data in Fig. 3, ϕ
was chosen individually for the right-handed and left-handed samples to display data where
they show similar features but with opposite handedness.
For the sample with straight nanorods, ϕ was chosen to show the highest value of m41
recorded in the measurements. The chosen growth parameters result in films with high PC
in the near-UV with largest values at 350 nm for the left-handed film and at 370 nm for the
right-handed film. At the selected sample orientation the degree of circular polarization of the
right-handed film exceeds 0.89. Ellipses representing the polarization state with highest PC can
be seen as insets in Fig. 3. Some interference oscillations due to the thickness of the transparent
film are also seen.
In the case with the straight-nanorod film non-zero values in m41 can be seen which could be
an effect of the nanorods being slightly tilted away from the sample surface normal. As can be
seen in Fig. 4 there are two values of ϕ where m41 are zero for all wavelengths, namely at 65◦
and 245◦ . At these sample orientations (called the pseudoisotropic sample orientations [19,20])
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the tilted nanorods are parallel to the plane of incidence, and the upper-right four and lower-left
four elements of the Mueller matrix will all be zero, including m41 [21]. However, simulations
and optical modeling suggest that the values in m41 are too large to be explained solely by
a tilt of the nanorods and that it is likely that also the nominally straight nanorods have a
compositional gradient and therefore an internal chirality, not unlike the one in the nanospirals.
The true origin of the non-zero values in m41 is under investigation and will be dealt with in
future publications.
a Left handed
b
c
Straight
360
360
180
180
180
Rotation Angle, φ (°)
360
0
0
0
360
360
360
180
180
180
0
0
0
360
360
360
180
180
180
0
245
500
750
1000
0
245
500
750
1000
0
245
Wavelength, λ (nm)
Right handed
500
750
1000
Figure 4. Polarizance vectors, [m21 , m31 , m41 ]T , at a fixed θ (25◦ ) of films with a) a lefthanded chiral film, b) a straight nanorod film and c) a right-handed chiral film. Notice that
the sharp borders between colored areas in the figure are due to the color scale used and
that all transitions are gradual.
The full Mueller matrix of each sample can be found in the appendix as ϕ–λ and θ –λ
contour plots. In order to sort out the most important data only the polarizance vector will be
displayed here. As discussed in chapter two, the polarizance vector equals the Stokes vector
of the reflected light when the incident light is unpolarized and according to Eq. (6) the third
element of the polarizance vector shows the degree of circular polarization. Figure 4 show
results from MMSE measurements at different sample orientations at a fixed incident angle of
25◦ . The data are shown as ϕ–λ contour plots of the polarizance vector with the element values
in color code. In Fig. 4(a) the polarizance vector of the sample with a left-handed chiral film
is shown. In a narrow band at approximately 350 nm the absolute value of m41 is large which,
according to Eq. (6), corresponds to a high degree of circular polarization. The sign is negative
which means that the unpolarized light incident on the left-handed chiral film is, to a large
extent, reflected as left-handed polarized light for all orientations of the sample. For the film
with a right-handed structure (Fig. 4(c)) the same behavior is found on 370 nm but in this case
with a positive value of m41 , that is, the unpolarized incident light is reflected as right-handed
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polarized light. In Fig. 4(b) the polarizance vector of the straight nanorod film is presented.
Here no sharp band of large m41 -values can be found, indicating that the polarized part of the
reflected light is mostly linear. The dependence of the polarizance vector on incidence angle
Angle of Incidence, θ (°)
a
b
Left handed
c
Straight
25
25
25
45
45
45
65
65
65
25
25
25
45
45
45
65
65
65
25
25
25
45
45
45
65
245
500
750
1000
65
245
500
750
1000
65
245
Right handed
500
Wavelength, λ (nm)
750
1000
Figure 5. Polarizance vectors, [m21 , m31 , m41 ]T , at the same ϕ as in Fig. 3 of samples with
a) a left-handed chiral film, b) a straight nanorod film and c) a right-handed chiral film.
and wavelength is shown in Fig. 5 as a θ –λ contour plot and the effect of filtering unpolarized
light into circularly polarized light is found in a narrow band centered on 370 nm for the righthanded nanorods and on 350 nm for the left-handed nanorods. The polarization phenomenon
can be seen to shift slightly towards shorter wavelengths (blue shift) with increasing θ . This
is consistent with the behavior of optical properties of chiral sculptured thin films as found by
simulations [6, 23] and experimental investigations [13].
The transformation of the polarization state upon reflection seems to be almost independent
of the azimuth angle ϕ for the two chiral films investigated. The small angular variations are
probably caused by imperfections in the layered structure of the films. The difference in spectral
response between the two chiral films is attributed to the difference in thickness and pitch
between the films. This effect may be utilized as a means to shift the wavelength dependence of
the filtering properties or to broaden the wavelength range by making a distribution of pitches
throughout the length of the nanospirals as has been done by Park et al. using GLAD [24].
5.
Concluding remarks
We present a method of producing circularly polarized light using chiral sculptured thin films
of a semi-conducting material. The narrow-band polarization filters reflect light with a high
degree of circular polarization in the ultraviolet regime just outside the visible range. Future
work involves producing similar samples on transparent substrates to make transmission filters
with high degree of circular polarization. The pitch of the spirals will also be varied to make
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1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1396
filters for other wavelengths and with different bandwidth.
6.
Appendix
Here is presented the degree of circular polarization, Pc, of the light reflected from the samples
studied, assuming incident light of various polarization states. The incident polarization states
used are represented by the following Stokes vectors defined in a Cartesian xyz-system with
the xz-plane equal to the plane of incidence:
 
1
 1 

(8)
Linear, horizontal = 
 0 
0


1
 −1 

Linear, vertical = 
(9)
 0 
0
 
1
 0 
◦

(10)
Linear, +45 = 
 1 
0


1
 0 

(11)
Linear, −45◦ = 
 −1 
0
 
1
 0 

(12)
Circular, right − handed = 
 0 
1


1
 0 

(13)
Circular, le f t − handed = 
 0 
−1
Pc is calculated according to Eq. (6) and presented in Figs. 6–14 with Pc calculated for
unpolarized incident light as a reference.
Figures 4 and 5 in section 4.2 show the polarizance vectors of the samples as ϕ–λ and θ –
λ contour plots. For a more complete description of the optical properties, the full Mueller
matrices, again as ϕ–λ and θ –λ contour plots, of the samples are presented in Figs. 15– 20
with auto-scaling for each matrix element to emphasize details. The incidence angle, ϕ, and
rotation angle, θ are the same as in Figs. 3 and 5.
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Degree of circular polarization, Pc
Wavelength, λ (nm)
Degree of circular polarization, Pc
Figure 6. Degree of circular polarization, Pc, at θ =25◦ of a sample with a right-handed
chiral film, illuminated with linearly polarized light specified in the inset.
Wavelength, λ (nm)
Degree of circular polarization, Pc
Figure 7. Degree of circular polarization, Pc, at θ =25◦ of a sample with a right-handed
chiral film, illuminated with linearly polarized light specified in the inset.
Wavelength, λ (nm)
Figure 8. Degree of circular polarization, Pc, at θ =25◦ of a sample with a right-handed
chiral film, illuminated with circularly polarized light specified in the inset.
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Degree of circular polarization, Pc
Wavelength, λ (nm)
Degree of circular polarization, Pc
Figure 9. Degree of circular polarization, Pc, at θ =25◦ of a sample with a left-handed chiral
film, illuminated with linearly polarized light specified in the inset.
Wavelength, λ (nm)
Degree of circular polarization, Pc
Figure 10. Degree of circular polarization, Pc, at θ =25◦ of a sample with a left-handed
chiral film, illuminated with linearly polarized light specified in the inset.
Wavelength, λ (nm)
Figure 11. Degree of circular polarization, Pc, at θ =25◦ of a sample with a left-handed
chiral film, illuminated with circularly polarized light specified in the inset.
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(C) 2014 OSA
Received 5 May 2014; revised 12 Jun 2014; accepted 13 Jun 2014; published 19 Jun 2014
1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1399
Degree of circular polarization, Pc
Wavelength, λ (nm)
Degree of circular polarization, Pc
Figure 12. Degree of circular polarization, Pc, at θ =25◦ of a sample with a straight nanorod
film, illuminated with linearly polarized light specified in the inset.
Wavelength, λ (nm)
Degree of circular polarization, Pc
Figure 13. Degree of circular polarization, Pc, at θ =25◦ of a sample with a straight nanorod
film, illuminated with linearly polarized light specified in the inset.
Wavelength, λ (nm)
Figure 14. Degree of circular polarization, Pc, at θ =25◦ of a sample with a straight nanorod
film, illuminated with circularly polarized light specified in the inset.
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(C) 2014 OSA
Received 5 May 2014; revised 12 Jun 2014; accepted 13 Jun 2014; published 19 Jun 2014
1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1400
Rotation Angle, φ (°)
Wavelength, λ (nm)
Rotation Angle, φ (°)
Figure 15. Normalized Mueller matrix, at a fixed θ (25◦ ) of a sample with a left-handed
chiral film.
Wavelength, λ (nm)
Figure 16. Normalized Mueller matrix, at a fixed θ (25◦ ) of a sample with a right-handed
chiral film.
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(C) 2014 OSA
Received 5 May 2014; revised 12 Jun 2014; accepted 13 Jun 2014; published 19 Jun 2014
1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1401
Rotation Angle, φ (°)
Wavelength, λ (nm)
Angle of Incidence, θ (°)
Figure 17. Normalized Mueller matrix, at a fixed θ (25◦ ) of a sample with a straight
nanorod film.
Wavelength, λ (nm)
Figure 18. Normalized Mueller matrix, at a fixed ϕ of a sample with a left-handed chiral
film.
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(C) 2014 OSA
Received 5 May 2014; revised 12 Jun 2014; accepted 13 Jun 2014; published 19 Jun 2014
1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1402
Angle of Incidence, θ (°)
Wavelength, λ (nm)
Angle of Incidence, θ (°)
Figure 19. Normalized Mueller matrix, at a fixed ϕ of a sample with a right-handed chiral
film.
Wavelength, λ (nm)
Figure 20. Normalized Mueller matrix, at a fixed ϕ of a sample with a straight nanorod
film.
Acknowledgments
This work is supported by the Swedish Research Council and CeNano. Knut and Alice Wallenberg foundation is acknowledged for support to instrumentation.
#211227 - $15.00 USD
(C) 2014 OSA
Received 5 May 2014; revised 12 Jun 2014; accepted 13 Jun 2014; published 19 Jun 2014
1 July 2014 | Vol. 4, No. 7 | DOI:10.1364/OME.4.001389 | OPTICAL MATERIALS EXPRESS 1403
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