Contents I. Introduction
Highly compact and cost-effective optical transceivers are needed to deal with the exponential growth in data traffic generated in telecommunication networks. 100-Gbit/s Ethernet (100GbE), standardized as IEEE 802.3ba [1], has a long reach specifications as regards its use with single-mode fiber (SMF), namely 100GBASE-LR4 for 10-km and 100GBASE-ER4 for 40-km. The specifications employ a multi-lane configuration that has four 25.78125 Gbit/s lanes with local area network wavelength division multiplexing (LAN-WDM), which is assigned a wavelength channel spacing of 800 GHz in the 1.3- wavelength band. To further reduce both the size and power consumption of the 100GbE transceiver, a CFP4 transceiver has been under discussion in relation to the centum form-factor pluggable (CFP) multi-source agreement (MSA) [2]. To obtain a multi-lane transmitter optical sub-assembly (TOSA) for a CFP4 transceiver that satisfies 100GBASE-ER4, it is important to pursue TOSA miniaturization while realizing an average optical output power ( of over −1.5 dBm at a minimum dynamic extinction ratio (DER) of 8 dB to keep an optical modulation amplitude (OMA) of over 0.1 dBm.
