Extremely Low-Noise High-Speed VCSELs for Optical Interconnects

When looking into high-speed data transmission using data rates greater than the noise behavior of the transmitter becomes more and more important. Vertical-cavity surface-emitting lasers (VCSELs) emitting at wavelength are characterised for this purpose. Relative intensity noise (RIN) and small signal modulation measurements have been performed and re-sulting spectra are fitted to theoretical curves in order to obtain internal device parameters. Different operation regimes, where transverse single- or multi-mode emission occurs, are in-vestigated. At low temperatures the quantum efficiency of the VCSEL is increased, leading to photon-number fluctuations below the shot noise limit. A special electrical probing is used to minimize parasitics and to inhibit RF-interference. 1