Diploma thesis

that the phasematching point was shifted out of the detection range. As an additional
remark the scaling is not comparable to the first measurements. Differences in
the incoupling into the spectrometers render any quantitative comparison between
the different measurement series impossible. For the full data set please refer to
Shg power Pump power [a.u.]
8
7
6
5
4
3
2
1
Shg spectrum
Pump spectrum
Mapping pump wavelength to shg wavelength
0
700 720 740 760 780 800 820 840
Shg wavelength [nm] Pump wavelength [nm/2]
Figure 4.19: No phasematching
Shg power Pump power [a.u.]
8
7
6
5
4
3
2
1
Shg spectrum
Pump spectrum
Mapping pump wavelength to shg wavelength
0
700 720 740 760 780 800 820 840
Shg wavelength [nm] Pump wavelength [nm/2]
Figure 4.20: New peak
appendix A.4.2.
To authenticate these measurements, we scanned another waveguide in the crystal,
from 1520 to 1660 nm pump wavelength (Figures 4.21 to 4.24). The data is in full
accordance with our first experiment. The spectral distributions are clearly amplified
towards the phasematching point at 780 nm, where a huge gain increase occurs (full
data in Appendix A.4.2).
Taking everything into account, we identified one phasematching point for crystal
BCT0703-B12 at 780 nm. At this point the chip fulfills the phasematching condition
and therefore it exhibits ∆k = 0.
How does the theory match with this data? To account for errors, we introduce a
new kE-vector into our phasematching function. This error or fitting vector is used
to fit the predictions of the theory to the experimental data.
∆k = kSHG − kp1 − kp2 − kΛ − kE
(4.10)
For crystal BCT0703-B12, with a poling period of 92 µm we get a kE-vector of
-0.02410 / µm (see Table 4.2).
kSHG 14.1787 / µm
kp1 6.97257 / µm
kp2 7.29812 / µm
kΛ 0.06786 / µm
-0.02410 / µm
kE
Table 4.2: Calculated k-vectors of the observed degenerate SHG process
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