iXBlue ModBox VNA, Руководство пользователя

Страница: 36 / 36

ModBox VNA – User’s Manual
Ref. Ed. B – 12/05/2020 34
Figure 20: RC equivalent circuit model of the MZM with vertical and horizontal components
Thermal or humidity drift stands for optical output power fluctuations induced
by thermal or humidity variations. Local temperature variations induce
pyroelectric charge growth inside the LiNbO3 crystal. These charges migrate to
the outermost surfaces of the crystal and between the electrodes, thus leading
to a charge growth across the arms of the interferometer. This results on a
modified electric field seen by the crystal. This then shifts the sinusoidal transfer
curve as seen on fig.15, this thermal drift is then very similar in terms of the
physics consequences to the drift seen when applying a DC voltage on the DC
electrodes. One direction to mitigate this charge accumulation on the crystal
surfaces is to use elements meant at dissipating those charges.