The generation of enhanced three-mode continuously variable(CV)entanglement via difference-frequency amplification in an optical cavity above the threshold is investigated.The quantum entanglement characteristics among the pump,signal,and idler beams are demonstrated by applying a sufficient inseparability criterion for CV entanglement proposed by van Loock and Furusawa.Bright three-mode CV entanglement with different frequencies can be generated in this simple system when the optical cavity operates above its threshold,and the best three-mode CV entanglement can be obtained when the pump threshold parameter is modulated at aboutσ=1.3.
