40 Gbit/s modulation of 1550 nm VCSEL

The modulation characteristics of vertical-cavity surface-emitting lasers with a buried tunnel junction emitting in the important wavelength regime around 1.55 m are presented. For the first time it was possible to demonstrate bit rates up to 40 Gbit/s also in this waveband. The 3 dB bandwidth measured under continuous-wave driving conditions was higher than 19 GHz. The present devices were found to be somehow sensitive to the bit-pattern length, especially at high temperatures or data rates resulting in some error-flooring. Error-free performance could be demonstrated up to 35 Gbit/s at room temperature and up to 25 Gbit/s at 55°C.