  We present a pulsed and integrated, highly non-degenerate parametric
downconversion (PDC) source of heralded single photons at telecom wavelengths,
paired with heralding photons around 800 nm. The active PDC section is combined
with a passive, integrated wavelength division demultiplexer on-chip, which
allows for the spatial separation of signal and idler photons with efficiencies
of more than 96.5 %, as well as with multi-band reflection and anti-reflection
coatings which facilitate low incoupling losses and a pump suppression at the
output of the device of more than 99 %. Our device is capable of preparing
single photons with efficiencies of 60 % with a coincidences-to-accidentals
ratio exceeding 7400. Likewise it shows practically no significant background
noise compared to continuous wave realizations. For low pump powers, we measure
a conditioned second-order correlation function of g^(2)(0)=0.0038, which
proves almost pure single photon generation. In addition, our source can
feature a high brightness of <n_pulse>=0.24 generated photon pairs per pump
pulse at pump power levels below 100 uW. The high quality of the pulsed PDC
process in conjunction with the integration of highly efficient passive
elements makes our device a promising candidate for future quantum networking
applications, where an efficient miniaturization plays a crucial role.
