Equalizer-Free Transmission of 100-Gb/s 4-PAM Signal Generated by Flip-Chip Interconnection EADFB Laser Module

We fabricated a flip-chip interconnection lumped-electrode EADFB laser module and an optical receiver that includes a broadband electrical amplifier. Both have a 3-dB bandwidth of more than 50 GHz. Under 53.2-Gbaud 4-PAM (107 Gb/s) operation, clear eye openings were obtained without an equalizer even after a 2-km SMF transmission, and we obtained a BER of less than 2 × 10^-4 under error-free conditions using KP4 FEC without an equalizer also after a 2-km SMF transmission.

I. Introduction

Inter-data-center traffic is increasing exponentially thanks to the rapid spread of cloud computing and mobile services. And the Ethernet data rate has been increasing to handle this huge amount of traffic. 400-gigabit Ethernet (400 GbE) is now in the process of being standardized by an IEEE task force [1] . For long-reach applications, such as 2- and 10-km single-mode-fiber (SMF) transmission, there is the potential to employ a multi-lane interface with a data rate of 8 × 50-Gb/s/λ. And the wavelength band will be 1.3 μm. To meet these requirements, a lumped-electrode electroabsorption modulator integrated with DFB lasers (LE-EADFB lasers) [2]–[5] and directly modulated DFB lasers [6]– [9] have been reported.