A sinc function / temperature measurement from the single pass (spare) SHG is shown. The basic idea of the experiment was to see if the crystal is intact (it is). For this purpose, the crystal was pumped with 1064 nm and after one pass (single pass) it was checked how much green light was generated. The temperature was adjusted to find the best possible phase matching temperature.

No similarity to Mount Saint Helens, as described in 76239, was observed. Conclusion, the crystal is intact. (What seems strange is the asymmetry in the side maxima.)

• Pump power 20 mW
• Dark noise 0.9 µW
• Transmitted power 16.8 mW --> just 84 % power is transmitted (probably because the focus was too large, resulting in clipping somewhere inside the housing)
• Fit equation: A*(np.sinc((T-T0)/width))**2 
• Plot is dark noise corrected

Setup:

•  NTC (71-01T1002FF)
•  TEC (Laird)
•  controller (Thorlabs)