Photonic Crystal Silicon Optical Modulators: Carrier-Injection and Depletion at 10 Gb/s

We demonstrate 10 Gb/s modulation in a 200 μm photonic crystal silicon optical modulator, in both carrier-injection and depletion modes. In particular, this is the first demonstration of 10 Gb/s modulation in depletion mode and without pre-emphasis, in a Mach-Zehnder type modulator of this length, although moderate pre-emphasis can improve the signal quality. This is made possible by utilizing the slow-light of the photonic crystal waveguide, where the group index
ng
is ~ 30 and gives ~ 7 times enhancement in the modulation efficiency compared to rib-waveguide devices. We observe 10 Gb/s modulation at drive voltages as low as 1.6 V and 3.6 V peak-to-peak, in injection- and depletion-modes, respectively.