We experimentally investigate a double-pass parametric down-conversion scheme
for producing pulsed, polarization-entangled photon pairs with high visibility.
The amplitudes for creating photon pairs on each pass interfere to compensate
for distinguishing characteristics that normally degrade two-photon visibility.
The result is a high-flux source of polarization-entangled photon pulses that
does not require spectral filtering. We observe quantum interference visibility
of over 95% without the use of spectral filters for 200 femtosecond pulses, and
up to 98.1% with 5 nm bandwidth filters.Comment: 8 pages, 6 figure