214-Gb/s 4-PAM Operation of Flip-Chip Interconnection EADFB Laser Module

We fabricated a Hi-FIT LE-EADFB laser module. Hi-FIT, which is a wire-free interconnection technique, provides a higher modulation bandwidth and a flatter frequency response than a conventional wire interconnection technique. The fabricated module has a 3-dB bandwidth of about 59 GHz and a sufficiently flat frequency response of less than 45 GHz. Using this module, we demonstrated a single-wavelength single-polarization direct-detection 4-PAM transmission with a record net data rate of 200 Gb/s. And with 4-PAM operation at 214 Gb/s, we obtained a BER of less than 3.8 × 10^-3, which is an error-free condition using a 7%-OH HD-FEC code, even after a 10-km SMF transmission.

I. Introduction

Internet traffic is increasing rapidly thanks to the expansion of cloud services. And there is now particular need for high-speed optical communication standards for inter- and intra-data centers. In response to this need, the Ethernet data rate has been increasing continuingly, and 400-gigabit Ethernet (400GbE) is being standardized [1]. It will employ an 4-intensity-level pulse amplitude modulation (PAM) scheme for long reach applications (2- and 10-km single-mode-fiber (SMF) transmissions). And the wavelength band will be 1.3 μm (1270–1310 nm). Optical transmitters have been reported that meet this requirement [2]–[6] . However, a decrease in the number of lanes is desirable to reduce both transceiver size and power consumption.