DIFFERENCE SQUEEZING IN 4-WAVE DIFFERENCE-FREQUENCY-GENERATION

The multimode difference squeezing of the electromagnetic field in the four-wave mixing process is investigated under the short-time approxi mation based on a fully quantum mechanical approach. It is shown that for uncorrelated modes the normal squeezing in the difference-frequenc y field depends on the difference squeezing of input field modes, whic h can generate normal squeezing in the difference-frequency field mode . Various possibilities for obtaining difference squeezing iii three m odes and its dependence on squeezing of individual field modes are inv estigated. If one of the high-frequency modes is squeezed and the othe r two modes are in coherent states, difference squeezing can be genera ted when the amplitude of the low-frequency mode is large enough. Diff erence squeezing can be generated in the three modes if one of the hig h-frequency modes is in a coherent state and the other two modes are d ifference squeezed. It is also shown that when the low-frequency mode is in a coherent state and the high-frequency modes are sum squeezed, then difference squeezing can be generated for large amplitude of the low-frequency mode.