Impact of the sample modal composition of 850nm VCSELs on high speed data transmission over multimode fiber applying different modulation formats

Modern high speed multimode fibers exhibit very low modal dispersion but suffer from the chromatic dispersion in glass, which is rather high at 850nm. To increase the transmission capacity on multimode fibers tested two approaches are applied and evaluated. On the transmitter side we designed and fabricated novel types of Vertical Cavity Surface Emitting Lasers (VCSELs) with spectrally ultra-narrow lasing emission both through achieving simple transverse mode operation and the negligible chirp. For increasing the transmission efficiency high-order modulation formats capable to increase the transmission capacity per single transmitter are applied. We report on development of very fast optical VCSEL and photodiodes within the European Project ADDAPT and show our recent results on high speed transmission over multi-mode fiber using 850nm VCSELs and GaAs PIN photodiodes applying different modulation formats. We show that the transmission distance and the transmission capacity of a single lane can be improved by applying high speed single mode VCSELs which are modulated with 4-PAM, 8-PAM and DMT modulation.