KAGRA MIR (Absorption)
ManuelMarchio - 00:17, Saturday 17 October 2015 (193)
GaAs absorption measurement at Spectrophotometer

I measured 3 samples of GaAs wafer from LMA.

Reflection measurement is taken at 12°.

Light is not polarized.

Plots show the spectrum of Transmission, Reflection and Absorption ( A = 100% - T - R ).

At 1064nm the absorption is about 4%. After 1300nm absorption becomes negative, down to -2%.

Images attached to this report
193_20151016171144_screenshotfrom20151016232044.png 193_20151016171200_screenshotfrom20151016232001.png 193_20151016171211_screenshotfrom20151016231917.png
Comments related to this report
ManuelMarchio - 18:27, Tuesday 20 October 2015 (196)

I used the Fresnel laws to determine wether or not the angle 12° would affect the Reflection measurement.

If the light was polarized the difference between 12° and 0° would be 2.5%

But the spectrophotometer SolidSpec-3700 have unpolarized light, and the difference between 12° and 0° is a factor of 1.5e-5 (0.0015%).

Not enough to affect the measurement, unless the light was polarized for some reason.