Low-loss high-speed silicon Mach-Zehnder modulator for optical-fiber telecommunications

Abstract

Low-loss high-speed traveling-wave silicon Mach-Zehnder modulator with reduced series resistance is studied in microwave and optical measurements. Microwave impedance and propagation loss under reverse bias are characterized by S-parameter measurements. Resonant loss due to series inductance-resistance-capacitance coupling limits microwave performances of the traveling-wave modulator. High-speed optical performances are characterized, based on eyediagram measurements in on-off keying at 10-32 Gb/s and constellation and eye-diagram measurements in differential phase-shift keying at 20 Gb/s. Dispersion tolerance in error-free transmission in 10-Gb/s on-off keying and 20-Gb/s differential phase-shift keying is obtained as +/-950 ps/nm and +/-220 ps/nm, respectively by path-penalty measurements. Transmission performance in 10-Gbps on-off keying is comparable with lithium niobate Mach-Zehnder modulator.

Silicon-based phase shifters for high figure of merit in optical modulation

“…The dimensions were determined to achieve high modulation speed and low optical loss. 13,14 Higher slab provides lower series resistance and faster phase modulation, whereas optical loss is higher due to weaker mode confinement in the center rib area with the slab height higher than 95 nm. The Si MZMs were fabricated on 8-inch SOI wafers of 220-nm SOI thickness and 2-μm buried-oxide (BOX) thickness using 130-nm node CMOS processes.…”