Low Voltage Silicon Photonic Modulators and Switches for High Radix Integrated Transmitters

In this paper, we summarize the latest results on silicon electro-optical (E/O) modulators in the framework of the European project L3MATRIX. The (E/O) devices were fabricated in a 0.350 mu m CMOS commercial production foundry (AMS AG) without recurring to CMOS-incompatible materials or processes deviating from ams AG foundry standards Our symmetric O-band modulator and C-band switch designs were based on alignment-tolerant vertical pn junctions with high doping concentrations such that a high priority is given to low voltage operation enabled by the high modulation efficiency around 3.2V.mm. First, the 1.25mm-long lumped electrode switch operates under 0.6V peak-to-peak differential voltages and approximate to 1ns rise/fall times. Beyond-1Vpp operation allows smaller switching time values due to capacitance reduction. Moreover, the 0.93mm-long travelling-wave (TW) modulators operates at 8Gbps with 1.6V peak-to-peak differential voltage as specified by the maximum output voltage of the control IC (1.8V). 10 Gbps modulation is achieved with higher swing voltages (2.3Vpp) to circumvent the bandwidth limitations likely due to the capacitive nature of the modulator as well as the electrode design. Finally, enhanced O-band slow light modulators are explored.