30-km Error-Free Transmission of Directly Modulated DFB Laser Array Transmitter Optical Sub-Assembly for 100-Gb Application

We fabricated the first compact 100-gigabit Ethernet (100GbE) transmitter optical sub-assembly (TOSA) using a directly modulated DFB laser (DML) array monolithically integrated with an optical multiplexer. Specially designed InGaAlAs/InGaAlAs multiple quantum wells make it possible to obtain a large gain in the 1295-1310-nm wavelength range and to operate at a high temperature of 55 °C. The four-channel DML array chip is only 2.0 mm × 2.4 mm in size, and the fabricated TOSA is only 7.2 mm(W ) × 14.3 mm(L) × 6.5 mm(H), which fits a CFP2 or smaller 100-GbE transceiver. For all the lanes, the 3-dB bandwidths of the TOSA exceeded 17 GHz, and it could operate at 25.8 Gb/s. With 25.8-Gb/s × four-channel simultaneous operation, error-free transmissions over a 30-km single-mode fiber were demonstrated for all the lanes.