Teng-Man Method

Teng-Mann Method for Measuring Electro-optic coefficient

Teng-Man Testing configuration

We use the Teng - Man method to measure R₃₃. R₃₃ is an elipsometric measurement. You apply a poling voltage to the film while making the elipsometric measurements and looking for changes in the signal. The stage can be heated until the film reaches its melting point T_g. These measurements are made with the materials in a device configuration. The formula for R₃₃

<math>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

\,\!</math> where

<math>I_m\,\!</math> is the amplitude of modulation

<math>V_{poly}\,\!</math> is the modulation voltage across EO polymer

<math>I_c\,\!</math> is the half intensity point

<math>n\,\!</math> is the refractive index of the polymer

and

<math>V_{poly}= V_{ACtot} \frac {d_{poly}} {d_{poly} + d_{clad}} \cdot \sqrt {\frac {\epsilon_{clad}} {\epsilon _{poly}}}\,\!</math>

Data from Teng-Mann measurement

The measured quanitities are:

<math>I= 2I_M\,\!</math> Modulated Intensity

<math>I_0 = 2I_C\,\!</math> Output intensity

<math>V_m = V_0 sin\omega t\,\!</math> Modulation Voltage

Real time optimization of r₃₃

Teng_Mann 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

See STC-MDITR research project 1.1

Technique

video to come