With Matteo, we worked on the red probe last week

before replacing the linear stage with the longer one, we checked what's the maximum signal we could get in this condition
we moved the linear stage to find the max of the AC/DC signal. As usual, everytime we moved the linear stage, we maximize the DC

- Pump laser current= 0.78, power= 30mW

- Reference sample surface

- DC max=3.15V

- AC/DC max =0.061

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Pump laser polarization

With Kuroki, we put a cube PBS right after the output fiber and measured the p and s polarization powers with the high-power power-meter
laser current 0.8A
420mW total power
325mW s-polarization
6-10mW p-polarization (power meter not very sensitive at this low power)

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Input Power Control

we put the half wave plate in front of the output fiber to rotate the polarization into p. Then we adjusted the angle of the first plate PBS to minimize the reflected beam.
Result: minimum of reflected (p-polarized) = 19mW  (transmitted400mW)
The strange thing is that the angle is about 64deg, much larger than 56deg