We analyze amplitude squeezing from a singly resonant frequency-doubli
ng laser oscillating at a single frequency, In this laser system, the
cavity loss depends on the intensity of the oscillating fundamental fi
eld, so that conventional analyses based on a mean-field approximation
become invalid in a highly pumped regime, To avoid this inconvenience
, we consider spatial evolution of fields both in a laser medium and i
n a nonlinear crystal, It is predicted for the first time that a combi
nation of excess nonlinearity and modest laser saturation can increase
the output noise, We propose novel indices to evaluate the possible n
oise enhancement and suggest a design rule for squeezed light generati
on.