High-speed Modulator for Next-generation Large-capacity Coherent Optical Networks

Abstract

Modulators with very high speeds are necessary to achieve the next-generation of 1-T/λ coherent optical networks.In this article, we describe our recently developed InP (indium phosphide)-based in-phase and quadrature (IQ) modulators with ultrahigh bandwidth and low half-wavelength voltage (V π ).We utilize a structure with extremely low electrical loss and obtain a 3-dB electro-optic bandwidth of over 67 GHz without degrading other characteristics such as driving voltage and optical loss.The IQ modulator performs IQ modulation at up to 120 Gbaud without optical and electrical pre-equalization.Furthermore, we developed an ultralow power modulator driver employing 65-nm CMOS (complementary metal-oxide semiconductor) technology and fabricated an IQ modulator co-assembled with this driver IC (integrated circuit), and successfully demonstrated 64-Gbaud/16QAM (quadrature amplitude modulation) operation.