  Reliable generation of single photons is of key importance for fundamental
physical experiments and to demonstrate quantum technologies. Waveguide-based
photon pair sources have shown great promise in this regard due to their large
degree of spectral tunability, high generation rates and long photon coherence
times. However, for such a source to have real world applications it needs to
be efficiently integrated with fiber-optic networks. We answer this challenge
by presenting an alignment-free source of photon pairs in the
telecommunications band that maintains heralding efficiency > 50 % even after
fiber pigtailing, photon separation, and pump suppression. The source combines
this outstanding performance in heralding efficiency and brightness with a
compact, stable, and easy-to-use 'plug & play' package: one simply connects a
laser to the input and detectors to the output and the source is ready to use.
This high performance can be achieved even outside the lab without the need for
alignment which makes the source extremely useful for any experiment or
demonstration needing heralded single photons.
