# Teng-Man Method

### Teng-Man Method for Measuring Electro-optic coefficient

Teng-Man Testing configuration

The Teng - Man method can measure R33 as the sample is being poled. R33 is an elipsometric measurement[1][2] . A poling voltage is applied to the film while making the elipsometric measurements and looking for changes in the AC signal generated by incident light. The stage can be heated until the film reaches its melting point Tg. These measurements are made with the materials in a device configuration. The formula for R33

$r_{33}= \frac {3\lambda I_m } {4 \pi V_{poly}I_c n^2 } \frac {(n^2 - sin^2 \theta) ^{1/2}}{sin^2 \theta} \approx I_m/ I_c \,\!$ where

$I_m\,\!$ is the amplitude of modulation
$V_{poly}\,\!$ is the modulation voltage across EO polymer
$I_c\,\!$ is the half intensity point
$n\,\!$ is the refractive index of the polymer

and

$V_{poly}= V_{ACtot} \frac {d_{poly}} {d_{poly} + d_{clad}} \cdot \sqrt {\frac {\epsilon_{clad}} {\epsilon _{poly}}}\,\!$

Data from Teng-Mann measurement

The measured quanitities are:

$I= 2I_M\,\!$ Modulated Intensity
$I_0 = 2I_C\,\!$ Output intensity
$V_m = V_0 sin\omega t\,\!$ Modulation Voltage

Real time optimization of r33

Teng-Man techniques allows real-time optimization of processing conditions because you can evaluate r33 during the poling process. It is used to confirm that a sample has been poled. The R33 measurement is best used as a relative measure because it can be inaccurate. Use attenuated total reflection ATR to get an accurate absolute measure.

See Khanarian 1996 [3]

See STC-MDITR research project 1.1 [4]

### References

1. http://en.wikipedia.org/wiki/Ellipsometry
2. SIMPLE REFLECTION TECHNIQUE FOR MEASURING THE ELECTRO-OPTIC COEFFICIENT OF POLED POLYMERS Teng CC, Man, HT APPLIED PHYSICS LETTERS Volume: 56 Issue: 18 Pages: 1734-1736 DOI: 10.1063/1.103107
3. Khanarian, et. al., JOSA B13, 1927 (1996)
4. http://stc-mditr.org/research/oeoaomd/projects/1.111.cfm Measuring R33 with Interferometry