Lumped Folded Michelson Interferometer Modulators With Broadband Technologies

Michelson interferometer modulators (MIMs) have superior modulation efficiency but shortcomings in high-frequency performance. We combine broadband technologies, the inductive and T-coil peaking technologies, with folded Michelson interferometer modulators (FMIMs) to make the device footprint more compact and improve the bandwidth of these modulators. A series of FMIMs are explored with different additional electric structures and electrode distribution with only 250-μm modulation areas. The on-chip insertion loss is about 1.22 dB for all FMIMs. Under 2 V reverse bias, the calculated Vπ-Ls of the modulators with GSG and GS electrodes are 0.933 V·cm and 1.284 V·cm. Both broadband technologies can enhance the high-frequency performances of FMIMs. The measured electro-optical (EO) bandwidths can reach 28.4 GHz for inductive peaking FMIMs at −6 V bias, which is 44 GHz for T-coil peaking at –2 V. The T-coil peaking FMIMs with the GSG lumped electrode (LE) and a 30-ohm terminal resistor can achieve a better trade-off between various performances with the clearer eye diagrams of 60 GBaud 4-level pulse amplitude Modulation (PAM4) and 60 Gbps On-Off Keying (OOK).