Optical Generation of Single- or Two-Mode Excited Entangled Coherent States

With nonlinear Mach--Zehnder interferometer (NLMZI) and a type-I beta-barium borate (BBO) crystal, we optically generate single-mode excited entangled coherent states. This scheme can be easily generalized to generate two-mode excited entangled coherent states. We simply analyse different influences of single- and two-mode photon excitations on entangled coherent states