In this paper, we perform a comparison of three modulation formats: NRZ, duo binary and DMT in combination with the state of the art 850 and 910nm VCSELs for their application in short reach high speed optical links. The system for NRZ and DB utilizes feasible for deployment equalization including a 9-tap finite impulse response filter and raised cosine filtering in the transmitter and a 7-tap UI-spaced feed forward equalizer in the receiver. The 100 Gbit/s net link with DB modulation can be realized without applying receiver equalization. For DMT the highest gross data rate of 224 Gbit/s/lambda is achieved.
In today’s fiber-optic communication systems, the bandwidth of the photonic components, i.e. modulators and photo diodes, is way greater than that of their electrical counterparts, i.e. digital-to-analog converters (DACs) and analog-to-digital converters (ADCs). In order to increase the transmission capacity, the bandwidth limitations need to be overcome. We review the progress and the recent results in the field of high-speed DACs, which are desirable for software-defined transmitters. Furthermore, we evaluate interleaving concepts regarding their ability to overcome the above mentioned limitations and demonstrate recent experimental results for a bandwidth interleaved DAC with 40 GHz analog electrical bandwidth.