Analysis of generation mechanism of photon-number squeezed light using ultrashort pulse and asymmetric fiber loop mirror

We analyze numerically the generation of photon-number squeezed light using an asymmetric fiber loop mirror. For photon-number squeezed light generati on, the maximum squeezing can be obtained using this method. The evolution of the quantum noise for the optical pulse spectra is calculated using the quantized nonlinear Schrodinger equation and linearization approximation. I t is shown that the squeezed light is generated by removing the increased q uantum noise part of the spectrum and enhancing the decreased quantum noise part of the spectrum, by the interference of two pulses at the beam splitt er. Although the mechanism of squeezing is similar to that of a spectral fi lter, the maximum squeezing is as large as -13 dB due to the interference.