Global data traffic is growing rapidly, and the demand for optoelectronic transceivers applied in data centers (DCs) is also increasing correspondingly. In this review, we first briefly introduce the development of optoelectronics transceivers in DCs, as well as the advantages of silicon photonic chips fabricated by complementary metal oxide semiconductor process. We also summarize the research on the main components in silicon photonic transceivers. In particular, quantum dot lasers have shown great potential as light sources for silicon photonic integration—whether to adopt bonding method or monolithic integration—thanks to their unique advantages over the conventional quantum-well counterparts. Some of the solutions for high-speed optical interconnection in DCs are then discussed. Among them, wavelength division multiplexing and four-level pulse-amplitude modulation have been widely studied and applied. At present, the application of coherent optical communication technology has moved from the backbone network, to the metro network, and then to DCs.

We report 25 Gb/s high-speed directly modulated ground-state operation of 1.3 μm InAs/GaAs quantum dot (QD) lasers grown by molecular beam epitaxy. The active region of the lasers consists of eight layers of p-doped InAs QDs with high uniformity and density. Ridge-waveguide lasers with a 3-μm-wide and 300-μm-long cavity show a low threshold current of 14.4 mA at 20°C and high temperature stability with a high characteristic temperature of 1208 K between 20°C and 70°C. Dynamic response measurements demonstrate that the laser has a 3 dB bandwidth of 7.7 GHz at 20°C and clearly opened eye diagrams even at high temperatures up to 75°C under a 25 Gb/s direct modulation rate.