  In this paper, we describe an experiment which was conducted to explore the
macro-coherent amplification mechanism using a two-photon emission process from
the first vibrationally-excited state of para-hydrogen molecule. Large
coherence in the initial state was prepared by the adiabatic Raman population
transfer method, and the lowest Stokes sideband was used as a trigger field. We
observed the coherent two-photon emission consistent with the expectation of
the paired super-radiance master equation.
