Zero-Chirp and Low Power PAM-4 Modulation Based on SOI Cascaded Multimode Interference Structures

Abstract

We present a new architecture for generation of multilevel pulse amplitude modulation (PAM-4) signal generation based on cascaded 4x4 multimode interference (MMI) structure used for optical interconnects and data centre network. The proposed device can generate two ring resonator structures with capability of critical coupling control. The push-pull configuration then is used at two ring resonators for PAM-4 level generation, so a zero chirp can be achieved. In this structure an M-shape transmission can be created for the first time. We use this property for an extreme reduction of power consumption with a lower level than 4-28 times compared with the PAM-4 generation based on the Mach Zehnder Modulator (MZM), respectively. Based on this structure, an extreme high bandwidth and compact footprint are also achieved. The whole device is designed and analyzed using the existing VLSI silicon photonics.