Photon number squeezing of spectrally filtered sub-picosecond optical solitons
Lehrstuhl für Optik, Physikalisches Institut der
Universität Erlangen Nürnberg, Staudtstr. 7/B2,
D-91058 Erlangen, Germany
Accepted: 26 March 1997
Photon number squeezing of spectrally filtered optical solitons has been observed in the sub-picosecond regime, where the Raman effect changes the internal quantum structure of each pulse. 160 fs pulses were propagated down a 10 m optical fibre of anomalous group velocity dispersion. At energies below the soliton energy subsequent spectral filtering with an optical band-pass squeezed the directly detected photocurrent fluctuations to dB (52%) below the shot-noise limit. This implies 4.5 dB (65%) of soliton photon number squeezing, if detection losses are taken into account. Using a spectral edge filter the spectral components of the pulses are shown to contribute asymmetrically to the squeezing due to stimulated Raman scattering.
PACS: 42.50.Dv – Nonclassical field states; squeezed, antibunched, and sub-Poissonian states; operational definitions of the phase of the field; phase measurements / 42.65.Tg – Optical solitons; nonlinear guided waves / 42.65.Dr – Stimulated Raman scattering; CARS
© EDP Sciences, 1997