  Bragg-reflection waveguides emitting broadband parametric down-conversion
(PDC) have been proven to be well suited for the on-chip generation of
polarization entanglement in a straightforward fashion [R. T. Horn et al., Sci.
Rep. 3, 2314 (2013)]. Here, we investigate how the properties of the created
states can be modified by controlling the relative temporal delay between the
pair of photons created via PDC. Our results offer an easily accessible
approach for changing the coherence of the polarization entanglement, in other
words, to tune the phase of the off-diagonal elements of the density matrix.
Furthermore, we provide valuable insight in the engineering of these states
directly at the source.
