Erratum: Spontaneous parametric down-conversion of photons at 660 nm to the terahertz and sub-terahertz frequency range

In this erratum, we correct two typing errors from our previously published manuscript [Opt. Express 27, 7458 (2019)]. In the original manuscript, the two errors were limited to the theoretical derivation and did not touch the numerical calculations such that the results and conclusions remain unchanged.