Lightwave Components Division
- A Ugai, Manager
- Lightwave Components Division
The amount of data transmission goes on increasing due to the high functionalization of mobile terminals, spread of social media and cloud computing. In addition, global online population is growing, especially in emerging countries. To meet the demand of data transmission, high-speed and large-capacity are required for network equipment like optical transmission equipment and optical switched/routers. In IEEE*1, 10 Gbit/s Ethernet (10GbE) was standardized as a transmission specification in 2002. Eight years later, in 2010, 100 Gbit/s Ethernet (100GbE) was standardized as the next generation specification(1). Among the 100GbE specifications, 100GBASE-LR4 (transmission distance: 10 km) and 100GBASE-ER4 (transmission distance: 40 km) are the specifications for middle/long distance between routers/switches or between neighboring data centers when using single mode fiber. In ITU-T*2 recommendation, G.959.1 (4I1-9D1F and 4L1-9C1F respectively)(2) are determined as specifications corresponding to the IEEE’s specifications. The optical transmitter modules we have developed are one of the key components in the optical transceiver (CFP)*3 (3) which converts an electrical signal to an optical signal and vice versa in the optical transmission equipment and optical switch/router. In the optical transceiver, the 100 Gbit/s electrical signal is divided into four 25 Gbit/s electrical signal lanes so that the data rate is suppressed per a lane, and four 25 Gbit/s lanes are allocated respectively to four optical transmitter modules whose wavelengths are four different ones, called LAN-WDM*4. We have developed 25 Gbit/s optical transmitter modules employing Electro-Absorption (EA) modulator integrated DFB laser (hereinafter referred to as “EA-DFB laser”*5) for 100 Gbit/s optical transceiver. In addition, when we commercialized these products, we developed two types of optical transmitter modules, including an in-house laser-diode driver IC(4) built-in type (hereinafter referred to as “driver IC built-in type”) and a type without a laser-diode driver IC (hereinafter referred to as “non-IC built-in type”), so that a user can select a transmitter module depending on the transceiver architectonics. In this paper, we describe the configurations, characteristics and long-term reliability of 25 Gbit/s optical transmitter modules.