YuefanGuo - 22:54, Friday 17 February 2017 (385)
Check the phase matching temperature
I found the green beam power as a function of the cavity temperature while scanning the cavity with 28Hz triangle wave. And the result shows in the first figure. Compared to the figure we got without the miniscope, it looks different.
Since directly we cannot see the temperature, the peak of the figure has the resistance of 3.265 kiloohm.
And in the following three pictures, the beam shape changes while the temperature change.
The second and the third pictures show that the beam start to get strange, inside this range, the beam basically is a spot, but as the temperature goes away from the maximum, there are more things around the spot.
We did some test today find out the reason why there is asymmetric of the resonance peak.
1.Set the temperature back to near room temperature, when there is no green light produced. In this way, we get rid of the effect of the green beam. But the asymmetric does not change much.
2. Change the laser crystal temperature, still nothing change.
We did not find the reason for the asymmetric, and also from the error signal, it seems there is some offset, but did not very clear where it comes from. I will change the PD to the one more sensitive to the infrared and with the 15MHz tuned.
Since directly we cannot see the temperature, the peak of the figure has the resistance of 3.265 kiloohm.
And in the following three pictures, the beam shape changes while the temperature change.
The second and the third pictures show that the beam start to get strange, inside this range, the beam basically is a spot, but as the temperature goes away from the maximum, there are more things around the spot.
We did some test today find out the reason why there is asymmetric of the resonance peak.
1.Set the temperature back to near room temperature, when there is no green light produced. In this way, we get rid of the effect of the green beam. But the asymmetric does not change much.
2. Change the laser crystal temperature, still nothing change.
We did not find the reason for the asymmetric, and also from the error signal, it seems there is some offset, but did not very clear where it comes from. I will change the PD to the one more sensitive to the infrared and with the 15MHz tuned.
Images attached to this report
Comments related to this report
- Indeed the Pound-Drever signal looked strange.
Out of the resonance is very close to zero as it should. So there is no large electronic offset.
On one side of the resonance the signal is positive and looks relatively normal.
But on the other side of the resonance it's only slightly negative and when the cavity is at
resonance the signal is positive. A picture would have helped this explanation.
- When the cavity is at resonance we measured about 65 mW on the green beam coming
from the SHG and transmitted through the dichroich mirror. It would be nice to see how much
IR power we are injecting into the SHG cavity. It would also be interesting to see how much
green light is not transmitted by the dichroic mirror to have a full picture.
Out of the resonance is very close to zero as it should. So there is no large electronic offset.
On one side of the resonance the signal is positive and looks relatively normal.
But on the other side of the resonance it's only slightly negative and when the cavity is at
resonance the signal is positive. A picture would have helped this explanation.
- When the cavity is at resonance we measured about 65 mW on the green beam coming
from the SHG and transmitted through the dichroich mirror. It would be nice to see how much
IR power we are injecting into the SHG cavity. It would also be interesting to see how much
green light is not transmitted by the dichroic mirror to have a full picture.