  Two schemes of projection measurement are realized experimentally to
demonstrate the de Broglie wavelength of three photons without the need for a
maximally entangled three-photon state (the NOON state). The first scheme is
based on the proposal by Wang and Kobayashi (Phys. Rev. A {\bf 71}, 021802)
that utilizes a couple of asymmetric beam splitters while the second one
applies the general method of NOON state projection measurement to three-photon
case. Quantum interference of three photons is responsible for projecting out
the unwanted states, leaving only the NOON state contribution in these schemes
of projection measurement.
