  Silicon waveguides are promising $\chi^3$-based photon pair sources.
Demonstrations so far have been based on picosecond pulsed lasers. Here, we
present the first investigation of photon pair generation in silicon waveguides
in a continuous regime. The source is characterized by coincidence
measurements. We uncover the presence of unexpected noise which had not been
noticed in earlier experiments. Subsequently, we present advances towards
integration of the photon pair source with other components on the chip. This
is demonstrated by photon pair generation in a Sagnac loop interferometer and
inside a micro-ring cavity. Comparison with the straight waveguide shows that
these are promising avenues for improving the source. In particular photon pair
generation in the micro-ring cavity yields a source with a spectral width of
approximately 150 pm resulting in a spectral brightness increased by more than
2 orders of magnitude.
