We present an experimental setup for generation of entangled-photon pairs via spontaneous parametric down-conversion,
based on the femtosecond-pulsed laser. Our entangled-photon source utilizes a 76-MHz-repetition-rate, 100-fs-pulsewidth,
mode-locked, ultrafast femtosecond laser, which can produce, on average, more photon pairs than a cw laser of an
equal pump power. The output infrared pump photons (λ = 810 nm) are first up-converted to blue light (λ = 405 nm)
and, subsequently, down-converted in a 1.5-mm-thick, type-II BBO crystal via spontaneous down-conversion. The
resulting entangled pairs are counted by a pair of high-quantum-efficiency, single-photon, silicon avalanche photodiodes.
The total down-conversion efficiency of our system, corresponding criterion of the pump power for real entangled
coincident events, has been calculated to be 0.86 × 10-9. Our apparatus is intended as an efficient source/receiver system
for the quantum communications and quantum cryptography applications.