Performance tradeoff between lateral and interdigitated doping patterns for high speed carrier-depletion based silicon modulators

Carrier-depletion based silicon modulators with lateral and interdigitated PN junctions are compared systematically on the same fabrication platform. The interdigitated diode is shown to outperform the lateral diode in achieving a low V pi L pi of 0.62 V.cm with comparable propagation loss at the expense of a higher depletion capacitance. The low V pi L pi of the interdigitated PN junction is employed to demonstrate 10 Gbit/s modulation with 7.5 dB extinction ration from a 500 mu m long device whose static insertion loss is 2.8 dB. In addition, up to 40 Gbit/s modulation is demonstrated for a 3 mm long device comprising a lateral diode and a co-designed traveling wave electrode. (C) 2012 Optical Society of America