  Quantum optics experiments frequently involve interfering single photons and
coherent states. In the case of multi-photon experiments this requires that all
photons are frequency degenerate. We report a simple and practical approach to
generate coherent states that can be readily tuned to any wavelength required,
for example by non-degenerate photon pair creation. We demonstrate this by
performing a two-photon (Hong-Ou-Mandel) interference experiment between a
coherent state and a pure heralded single photon source. No spectral filtering
is required on either source, the coherent state constrained by the pump and
seed lasers and the heralded photon exploits non-local filtering. We expect
that such an approach can find a wide range of applications in photonic based
quantum information science.
