PROPAGATION OF QUANTUM-PROPERTIES OF SUBPICOSECOND SOLITONS IN A FIBER

We present new results on photon number squeezing of spectrally filter ed solitons in fibers. The impact of frequency low-, high-, and bandpa ss filtering on noise reduction has been measured as a function of fib er length for 130-fs pulses close to the soliton energy. For short fib ers our results agree qualitatively with theoretical predictions. For longer fibers, however, the measured squeezing increases to an unexpec tedly large value. Spectral filtering of a strongly Raman-shifted, hig her energy pulse squeezed the directly detected photocurrent fluctuati ons down to 3.8+/-0.2 dB (59%) below the shot noise level. The measure d noise reductions are broadband from 5 to 90 MHz. (C) 1997 Optical So ciety of America.