Calligraphic poling is a technique for generating an arbitrary, possibly complex pattern of localized reversal in the direction of permanent polarization in a wafer of LiNbO3 or other ferroelectric material. The technique is so named because it involves a writing process in which a sharp electrode tip is moved across a surface of the wafer to expose the wafer to a polarizing electric field in the desired pattern. The technique is implemented by use of an apparatus, denoted a calligraphic poling machine (CPM), that includes the electrode and other components as described in more detail below

Iltchenko, Vladimir

Maleki, Lute

Matsko, Adrey

Mohageg, Makan

Savchenkov, Anatoliy

Strekalov, Dmitry

NASA Technical Reports Server

36 NASA Tech Briefs, September 2007
(bottom panel).  All AFIDS data are pre-
processed in the field with the use of a lap-
top computer equipped with LabVIEW™.
The AFIDS software can be programmed
to run continuously or at specific time in-
tervals when insects are prevalent.  
A special DC-restored transimped-
ance amplifier reduces the contribu-
tions of low-frequency background light
signals, and affords approximately two
orders of magnitude greater AC gain
than conventional amplifiers. This
greatly increases the signal-to-noise
ratio and enables the detection of small
changes in light intensity. The AFIDS
light source consists of high-intensity Al-
GaInP light-emitting diodes (LEDs).
The AFIDS circuitry minimizes bright-
ness fluctuations in the LEDs and when
integrated with an integrating sphere,
creates a diffuse uniform light field.
The insect wing beats isotropically scat-
ter the diffuse light in the sphere and
create wing-beat signatures that are de-
tected by the sensor.  This configuration
minimizes variations in signal associated
with insect flight orientation.  
Preliminary data indicate that AFIDS
has sufficient sensitivity and frequency-
measuring capability to differentiate be-
tween male and female mosquitoes (Fig-
ure 1, bottom panel) and fruit flies
(data not shown).  Similar studies show
that AFIDS can be utilized to detect dis-
crete differences between two mosquito
species, Aedes aegypti and Aedes albopictus. 
When fully deployable, a wireless net-
work of AFIDS monitors could be used
in combination with other remotely
sensed data and visually displayed in a
geographic information system (GIS) to
provide real-time surveillance (see Fig-
ure 2). More accurate and sensitive in-
sect population forecasts and effective
rapid response and mitigation of insect
issues would then be possible. 
This work was done by Timi Vann of Sten-
nis Space Center and Jane C. Andrews, Dane
Howell, and Robert Ryan of Lockheed Mar-
tin Corp. 
Inquiries concerning rights for the com-
mercial use of this invention should be ad-
dressed to the Intellectual Property Manager,
Stennis Space Center, (228) 688-1929.
Refer to SSC-00192.
1 
2 
3 
4 
Insect Density  
Histograms Highest 
Lowest 
Insect Density Histograms (Threat) 
Figure 2.  Integration of AFIDS and GIS Data Layers is illustrated for hypothetical military, civilian, or
agricultural pest management. Data layers are as follows:  (1) Hypothetical AFIDS insect density con-
tours (histograms = threat intensity); (2) STAR-3i radar imagery; (3) ASTER Normalized Difference Veg-
etative Index; and (4) LIDAR digital terrain.
Calligraphic Poling of Ferroelectric Material
Arbitrary patterns can be written relatively easily and inexpensively.
NASA’s Jet Propulsion Laboratory, Pasadena, California
Calligraphic poling is a technique for
generating an arbitrary, possibly com-
plex pattern of localized reversal in the
direction of permanent polarization in a
wafer of LiNbO3 or other ferroelectric
material. The technique is so named be-
cause it involves a writing process in
which a sharp electrode tip is moved
across a surface of the wafer to expose
the wafer to a polarizing electric field in
the desired pattern. The technique is im-
plemented by use of an apparatus, de-
noted a calligraphic poling machine
(CPM), that includes the electrode and
other components as described in more
detail below.
A capability for forming poling pat-
terns is needed for research on, and de-
velopment of, photonic devices that ex-
ploit the nonlinear optical properties of
ferroelectric crystals. Specific poling
structures in ferroelectric crystals can be
engineered to variously amplify or sup-
press these nonlinear optical properties
to effect such useful functions as optical
switching, modulation, frequency con-
version, and frequency filtering.
Outside of industry, poling machines
have been available to only a few re-
search laboratories and have been typi-
fied by high costs and limited flexibility.
Prior poling techniques and machines
are suitable for generating relatively sim-
ple patterns (e.g., straight lines) but are
not suitable for generating the arbitrary
patterns required in some applications.
Each of the prior techniques involves
one or more of the following: expensive
fabrication of electrically conductive
masks, expensive holograms, a clean-
room, high vacuum, and high tempera-
ture. In contrast, a CPM operates in air
at room temperature with equipment
readily available in a typical laboratory;
hence, calligraphic poling costs less than
does poling by the prior techniques.
In a CPM (see figure), the wafer to be
poled is placed in the x–y (horizontal)
https://ntrs.nasa.gov/search.jsp?R=20100010906 2019-08-30T09:01:39+00:00Z
plane on a smooth, flat substrate that
serves as a lower electrode. Typically,
the wafer is a crystal of LiNbO3 or other
ferroelectric material that is z-cut. [In
this case, “z-cut” signifies that the polar-
ization axis of the wafer is perpendicu-
lar to its broad faces and thus coincides
with the z (vertical) axis when the wafer
is placed on the substrate]. A thin layer
of saltwater is placed between the sub-
strate and the wafer to ensure electrical
contact between the nominally planar
wafer and substrate surfaces. The thin
layer of saltwater also serves to mechan-
ically bind the wafer temporarily to the
substrate. The electrode has a tungsten
tip 0.5 μm wide and is biased at a suit-
able potential with respect to the sub-
strate (typically, ≈1.5 kV for a 100-μm-
thick LiNbO3 crystal). The writing
electrode is mounted on an x–y transla-
tion stage, which is used to move the
electrode across the wafer surface in
the desired pattern.
By varying the magnitude and dura-
tion of the applied voltage in conjunc-
tion with the motion or stationarity of
the electrode, one can exert some con-
trol over the sizes and shapes of the fer-
roelectric domains. For example, it was
found that smooth lines having widths of
the order of a few microns could be
formed by applying potentials between
0.8 and 1.8 kV for times of the order of
10 s while the pen was moving, as illus-
NASA Tech Briefs, September 2007 37
Magnified 
View 
Showing 
Width of 
Ring 
LiNbO3 Disk Ring Pattern 
Electrode 
2 μm 
Electrode 
3 μm 
Figure 2. These Are Two Examples of patterns made by calligraphic poling. The images at the left show a 2-μm-wide ring formed on a 100-μm-thick LiNbO3
disk at a potential of 1.8 kV applied during a writing time of 10 s. The image at the right shows a 3-μm-wide hexagonal domain formed on a 120-μm-thick
LiNbO3 crystal by use of a 2.5-kV bias applied to a stationary electrode for 1.5 s.
Figure 1. A Sharp Electrode applies a strong electric field to effect localized poling of the wafer. Used
like a pen, the electrode is moved across the wafer to write a poling pattern.
Source of 
High Voltage 
Writing 
Electrode 
Wafer of 
Ferroelectric Material 
(Arrows Represent 
Permanent 
Polarization) 
Thin Film of 
Saltwater 
Electrically 
Conductive 
Substrate 
38 NASA Tech Briefs, September 2007
trated in the left part of the figure. For
another example, it was found that po-
tentials between 2 and 3 kV applied for
times <2 s while the electrode was held
stationary yield hexagons (a conse-
quence of the crystalline structure of
LiNbO3), as illustrated in the right part
of Figure 2.
Among the advantages of calligraphic
poling is that it is possible to visually ob-
serve the domains in ordinary (that is,
non-polarized) light as they are being
formed. Light incident from above
along the z-axis travels through the
wafer and is reflected from its bottom
surface. The poling electric field magni-
fies the gradient in the index of refrac-
tion between a +z- and –z-poled region
to such an extent as to give rise to a dark
outline, coinciding with the boundary
between the regions, that is visible in the
reflected light when viewed from above
through a conventional optical micro-
scope. In addition, it is possible to view
the domains nondestructively after they
have been formed, because a potential
sufficient to generate the dark outline
(typically 200 V) is much smaller than
the domain-reversal potential.
This work was done by Makan Mohageg,
Dmitry Strekalov, Anatoliy Savchenkov,
Adrey Matsko, Lute Maleki, and Vladimir
Iltchenko of Caltech for NASA’s Jet Propul-
sion Laboratory. 
In accordance with Public Law 96-517, the
contractor has elected to retain title to this in-
vention. Inquiries concerning rights for its
commercial use should be addressed to:
Innovative Technology Assets Management
JPL
Mail Stop 202-233
4800 Oak Grove Drive
Pasadena, CA 91109-8099
(818) 354-2240
E-mail: iaoffice@jpl.nasa.gov
Refer to NPO-41566, volume and number
of this NASA Tech Briefs issue, and the
page number. 
Blackbody Cavity for Calibrations at 200 to 273 K
Care must be taken to ensure high emissivity to minimize error.
Stennis Space Center, Mississippi
A laboratory blackbody cavity has been
designed and built for calibrating infrared
radiometers used to measure radiant tem-
peratures in the range from about 200 to
about 273 K. In this below-room-tempera-
ture range, scattering of background in-
frared radiation from room-temperature
surfaces could, potentially, contribute sig-
nificantly to the spectral radiance of the
blackbody cavity, thereby contributing a sig-
nificant error to the radiant temperature
used as the calibration value. The spectral
radiance error at wavelength λ is given by
[l – ε(λ)][B(Tc,λ) + B(Ta,λ)],
where ε(λ) is the effective spectral emissiv-
ity of the cavity, B(T,λ) is the ideal spectral
radiance of a body at absolute temperature
T according to Planck’s radiation law, Tc is
the temperature in the cavity, and Ta is the
ambient temperature. Examining the
above expression shows that by making
ε(λ) as close as possible to unity, one can
minimize the spectral-radiance error and
the associated radiant-temperature error.
For example, it has been calculated that to
obtain a radiant-temperature error of 1 K
or less at a cavity temperature of 200 K, am-
bient temperature of 300 K, and wave-
length of 6 μm, one has ε(λ)>0.999 (see
Figure 1). A 1 K radiant-temperature error
is more than sufficient for atmospheric
and cloud studies, which is a common ap-
plication of infrared radiometers.
The present blackbody cavity is of an es-
tablished type in
which multiple
reflections from a combination of conical
and cylindrical black-coated walls (see Fig-
ure 2) are exploited to obtain an effective
emissivity greater than the emissivity value
of the coating material on a flat exposed
surface. The coating material in this case is
a flat black paint that has an emissivity of
approximately 0.91 in the thermal spectral
range and was selected over other, higher-
emissivity materials because of its ability to
withstand thermal cycling. We found many
black coatings cracked and flaked after
thermal cycling due to differences in the
coefficient of expansion. On the basis of
theoretical calculations, the effective emis-
sivity is expected to approach 0.999.
2 
10–2 
10–1 
100 
101 
102 
4 6 8 
Wavelength, Microns 
Te
m
p
er
at
u
re
 E
rr
o
r, 
K
el
vi
n
 
10 12 14 
Emissivity = 0.99 
Emissivity = 0.999 
Emissivity = 0.9999 
 
300 K Ambient, 200 K Blackbody 
Figure 2. The Blackbody Cavity has a shape and size chosen as a compromise
among maximizing the number of internal reflections, maximizing effective
emissivity out to an acceptably large radius, and keeping the cone short
enough to fit in a Dewar flask, as shown.
Swing Cover for Hole Radiometer 
Positioned 
Here 
Air  
Hose 
Conical  
Blackbody  
With 2-in.  
Aperture 
Dry-Ice/ 
Isopropanol 
Slush 
14 in. 
Temperature  
Probe 
Feild of View = 2.5 in. 
@ 6.5 in. away  
target dia = 0.28 in. 
5.75 in. 
Figure 1. The Error in the Radiant Temperature as a function of wave-
length was calculated for three different emissivity values for a cavity
temperature of 200 K and ambient temperature of 300 K.


Calligraphic Poling of Ferroelectric Material

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