A high-speed widely tunable Šolc-type flat-top filter based on the dual transverse Pockels effect

A high-speed widely tunable Solc-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 Solc-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 Solc-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).