  We report on a process for the fiber-coupling of electrically driven
cavity-enhanced quantum dot light emitting devices. The developed technique
allows for the direct and permanent coupling of p-i-n-doped quantum dot
micropillar cavities to single-mode optical fibers. The coupling process, fully
carried out at room temperature, involves a spatial scanning technique, where
the fiber facet is positioned relative to a device with a diameter of 2 $\mu$m
using the fiber-coupled electroluminescence of the cavity emission as a
feedback parameter. Subsequent gluing and UV curing enables a rigid and
permanent coupling between micropillar and fiber core. Comparing our
experimental results with finite element method simulations indicates a
cavity-to-fiber mode-coupling efficiency of ~46%. Furthermore, we demonstrate
pulsed current injection at a repetition rate exceeding 200 MHz as well as
low-temperature operation down to 77 K of the fiber-coupled micropillar device.
The technique presented in this work is an important step in the quest for
efficient and practical quantum light sources for applications in quantum
information.
