Class-80 InP-based high-bandwidth coherent driver modulator with flexible printed circuit RF interface

We developed flexible printed circuit RF interface InP-based coherent driver modulators with a 3-dB bandwidth of over 80 GHz for 128-Gbaud or higher operations. Low insertion loss (<8.5 dB per polarization), low polarization-dependent loss (<0.1 dB), and high extinction ratio (>30 dB) were achieved.

Introduction

High capacity optical transport networks are required to meet the demand of increasing global IP traffic. Higher baud-rate and higher-order optical quadrature amplitude modulation (QAM) are key to enhancing the capacity of digital coherent optical systems [1],[2]. A high-bandwidth coherent driver modulator (HB-CDM) [3],[4] and high-bandwidth intradyne coherent receiver (HBICR) [5],[6] are important devices for high-speed transmission systems. In the HB-CDM configuration, a driver IC and a dual-polarization (DP) IQ modulator are assembled adjacent to each other in one package to reduce the radiofrequency (RF) loss and footprint. Standardization of the HB-CDM supporting operations at up to 128 Gbaud has been completed at the Optical Internetworking Forum (OIF) [4]. The HB-CDM for 128-Gbaud operations called class-80. The class number refers to the approximate EO 3-dB bandwidth. The highest 3dB bandwidth of HB-CDM reported so far is 66.7 GHz [7], but there are no reports of HB-CDMs with 3-dB bandwidth over 80 GHz (class-80) yet.