Silicon dual ring modulator driven by differential signal.
A silicon dual ring modulator consisting of two serially cascaded rings with embedded PN junctions is driven by a differential signal pair. We show by simulation and experiment that the device has advantages over the single ring modulator in terms of optical bandwidth, 3 dB modulation bandwidth and bit rate, at the expense of a 1.7 dB increase in the transmission penalty and a twofold increase of the RF power consumption. Driven by differential pseudo random binary sequence (PRBS) signals of 0.5 V peak to peak voltage (Vpp) the dual ring modulator exhibits optical bandwidths of 66 pm and 40 pm at 12.5 Gb/s and 20 Gb/s, respectively. In contrast, the single ring modulator has an optical bandwidth of 26 pm under a single end PRBS signal of 0.5 Vpp at 12.5 Gb/s, and its eye diagram closes if the bit rate rises to 20 Gb/s.
Optics letters