A high-speed widely tunable Šolc-type flat-top filter based on the dual
transverse Pockels effect is presented. The filter employs single-domain
LiNbO3
(LN) with two pairs of transverse electrodes, where the one along the
y-axis is periodic and the
other one along the z-axis is continual. The periodic electrode provides periodic electro-optic modulation along
the light propagation direction, which results in a folded Šolc-type filter. The continual
electrode giving a uniform electric field is in charge of tuning the transmitted central
wavelength of the filter. Compared to a conventional PPLN Šolc-type filter, our
setup has double electro-optic tuning efficiency and a much broader operating
range of intensity of the control electric field. In a safe region of electric field
intensity, the transmitted central wavelength can extend from 1488 to 1562 nm.
Since the tuning is via the Pockels effect, it has very fast response time (tens of
nanoseconds).