The continuous-time quantum theory of self-phase modulation (SPM) in l
ossless, dispersionless, single-mode fiber requires a nonzero response
time, to capture the classical SPM limit properly, and an accompanyin
g Raman noise, to ensure commutator preservation. The continuous-wave,
four-wave mixing limit of this theory is shown to harbor a Raman-nois
e limit on fiber-based squeezed-state generation.