Diploma thesis

Pump Power [a.u.]
25000
20000
15000
10000
5000
Figure 4.27: Measurement setup to simoultaneously detect SHG spectrum,
pump spectrum, SHG intensity and Pump intensity
λ p = 765 nm
λ p = 775 nm
λ p = 768 nm
Pump spectrum
0
740 750 760 770
λp [nm]
780 790 800
Figure 4.28: Applied pump spectra [nm/2]
SHG Power [µW]
7
6
5
4
3
2
1
λ p = 765 nm
λ p = 775 nm
λ p = 768 nm
SHG Gain
0
0 5 10 15 20 25 30 35
Input Power [µW]
Figure 4.29: Observed gain increase
Pump power levels below 5 µW are difficult to handle. Incoming SHG light remains
barely detectable and ambient light introduces additional noise. In this experiment
we detected a stronger SHG light at 765 nm than at 775 nm, at equal pump intensities.
This increase in conversion efficiency already predicts that the phasematching
point will be located below 1550 nm pump wavelength.
Comparison between different approaches
Before we switched to the alternate approach, we tested the equivalence of monitoring
the mapping between SHG and Pump spectrum and a measurement of the SHG
power. For this purpose we used the same setup as for the gain measurement 4.27.
The mappings plotted in Figures 4.30 to 4.33 show a phasematching around 760
nm SHG wavelength or at about 1520 nm pump wavelength. The full data is again
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