We study the quantum-noise properties of spectrally filtered solitons in optical fibers. Perturbation theory, including a quantum description of the continuum, is used to derive a complete analytical expression for the second-order correlator of the amplitude quadrature. This correlator is subsequently used to optimize the frequency response of the filter numerically in order to achieve the minimum photon-number noise. For propagation distances up to three soliton periods, the length at which the best noise reduction occurs, a square filter is found to be approximately optimum. For longer distances, more-complicated filter shapes are predicted for the best noise reduction.
© 1999 Optical Society of America
Dmitry Levandovsky, Michael Vasilyev, and Prem Kumar, "Perturbation theory of quantum solitons: continuum evolution and optimum squeezing by spectral filtering," Opt. Lett. 24, 43-45 (1999)