State-of-the-art and perspectives for long-wavelength high speed VCSELs

In this work, the latest advances in 1550 nm high-speed short-cavity (SC) VCSELs are presented. The electrical, optical and thermal design of these devices is discussed with respect to their high-speed modulation behaviour. The implemented design improvements allow high output powers for ambient temperatures up to 90°C, high differential quantum efficiencies up to 45%, low thermal resistances down to 1.6 K/mW, small-signal modulation bandwidths in excess of 17 GHz, and error-free data transmission at room-temperature at data rates of 25 Gbit/s over 4.2 km of single-mode fiber and 35 Gbit/s in back to back (B2B) configuration. The latter corresponds to rather small energies per bit of only 0.23 pJ/bit. At elevated temperatures of 55°C error-free transmission is achieved at 25 Gbit/s in B2B configuration.