Carrier depletion type PIN phase shifter in silicon MZM for 200 Gbps operation

Abstract

Silicon-based photonic modulators are a primary choice for on-chip optical devices with CMOS fabrication compatibility. The phase shifter in a silicon photonics modulator plays a significant role in determining the efficiency of the modulator to meet the optical data communication's future demands. Obtaining high extinction ratio (ER) and with acceptable bit error rate (BER) at low voltage and low loss was kept as the primary objective for the proposed PIN phase shifter in an unbalanced silicon Mach-Zehnder modulator. The phase shifter length was kept at 2 mm, and the carrier doping region was reduced to decrease the carrier absorption loss. The concentration of P and N in the phase shifter was set to 7 × 1017 cm−3 and 5 × 1017 cm−3, and the intrinsic gap was varied (50, 100, 150, 200, 250, 300, 350 and 450 nm) for the study to obtain the optimum gap to meet the objective. For 200 Gbps, the proposed modulator with intrinsic gap 150 nm obtained 18.68 dB ER having VπL = 0.8 V.cm. Insertion loss obtained for the phase shifter was 3.421 dB/cm. The proposed design is expected to enhance the performance of silicon optical modulators for commercial applications, and also other applications such as optical switches, delay lines, and optical interconnect.