High-speed modulation, wavelength, and mode control in vertical-cavity surface-emitting lasers

摘要

We address demands and challenges for GaAs-based Vertical-Cavity Surface-Emitting Lasers (VCSEL) in data communication. High speed modulation (～50Gb/s) at a high reliability can be realized with a proper VCSEL design providing a high differential gain. In cases where extreme temperatures are required electrooptic modulation in duo-cavity VCSELs can be applied as the modulation speed and the differential gain are decoupled. Single mode operation of VCSELs is necessary to counteract the chromatic dispersion of glass fibers and extend distances to above 1 km while using standard multimode fibers. Oxide layer engineering or using of photonic crystals can be applied. Parallel error-free 25Gb/s transmission over OM3 and OM4 multimode fiber (～0.5 and 1 km, respectively) is realized in large aperture oxide-engineered VCSEL arrays. Passive cavity VCSELs with gain medium placed in the bottom DBR and the upper part made of dielectric materials a complete temperature insensitivity of the emission wavelength can be realized. Engineering of the oxide aperture region enables near field vertical cavity lasers. Such devices can operate in a high-order transverse mode with an effective mode angle beyond the angle of the total internal reflection at the semiconductor-air interface. Near filed coupling to optical fibers and waveguides becomes possible in this case.