Two Mach-Zehnder-type tunable dispersion compensators integrated in series to increase bandwidth and/or range while maintaining single-knob control

We previously demonstrated a colorless three-stage Mach-Zehnder-interferometer-type 10-Gb/s tunable dispersion compensator (TDC) in a silica-on-silicon planar lightwave circuit. However, the bandwidth was too narrow to tolerate typical transmitter wavelength drift. Here we demonstrate a wider bandwidth version, in which we increased the TDC free-spectral range (FSR) and put two TDCs in series onto the same chip. Key features are that a single voltage tunes the entire device, and a single half-wave plate makes the entire device polarization insensitive. This 50-GHz FSR device allows 180 km of 9.95-Gb/s transmission. We also demonstrate a 100-GHz FSR version, which compensates /spl sim//spl plusmn/200 ps/nm of 42.7-Gb/s transmission.