64 Gbps Si photonic crystal slow light modulator by electro-optic phase matching

We demonstrate 64 Gbps operation in a compact Si photonic crystal optical modulator that employs meander line electrodes and compensate for the phase mismatch between slow light and RF signals. Although low dispersion slow light increases the modulation efficiency, maintaining a sufficiently wide working spectrum the phase mismatch becomes a limiting factor on the operation speed even when the phase shifter length is as short as 200 mu m. Meander line electrodes broke this limit and enhanced the cutoff frequency by up to 31 and 38 GHz using 50 Omega and 20 Omega termination resistors. respectively. This allowed to use a group index of slow light higher than 20 and greatly improved the quality of the modulation characteristics at 25 and 32 Gbps. Clear open eye was observed even at 40-64 Gbps. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement