A Wide Temperature 112-Gbaud PAM4 Operation of Lumped-EML Submodule Using Resistance-Optimized LC Resonance Effect

We present a high-speed (>70 GHz) lumped-EML submodule whose modulation bandwidth is enhanced by a resistance-optimized LC resonance effect. We perform an equivalent circuit analysis to determine the optimal value of a matching load resistance for 112-Gbaud PAM4 operation over wide temperature range of 25∼70 °C. By fabricating the lumped-EML submodule, we experimentally show that a 3-dB bandwidth of over 70 GHz can be obtained up to 70 °C by optimizing the matching load resistance as well as lengths of bondwires, even with a lumped-EML featuring a moderate EAM length of 120 μm. Consequently, the fabricated lumped-EML submodule revealed clear optical eye patterns under 112-Gbaud PAM4 modulation after 2-km SMF transmissions.