Previous investigations of stimulated Raman scattering in a multipass
cell have considered the amplification of a Stokes input pulse. They f
ound that a simple plane-wave transient theory, appropriately scaled t
o include the multiple passes and focusing, matched experimental data
well. In this paper, we investigate growth from spontaneous emission i
n a H-2 Raman multipass cell. We find that a fully-quantum-mechanical
scaled plane-wave theory describes the growth from spontaneous emissio
n well in the high-gain limit. However, in the low-gain regime there i
s a significant increase in the Stokes output which is not predicted b
y the scaled plane-wave theory.