Quantum statistics of fundamental and higher-order coherent quantum solitons in Raman-active waveguides

Abstract

The quantum dynamics of coherent optical pulses are studied using a nondiagonal coherent-state generalized $P$ representation including photon-phonon interactions. Photon-number squeezing of coherent quantum solitons using spectral filtering is theoretically predicted. It is shown that Raman noise does not significantly reduce photon-number squeezing produced by spectral filtering of 1-ps fundamental coherent quantum solitons in optical fibers. Coherent $Nsech$ pulses with $N>\mathrm{}1\mathrm{}$ can show a larger reduction in photon-number fluctuations even at room temperature. The reduction in quantum noise for $N>\mathrm{}1\mathrm{}$ is not restricted to photon number and an improvement of more than 3 dB is also found for the quadrature-phase squeezed soliton experiments using a fiber Sagnac interferometer at 77 K.