Non-classical photon statistics for two-mode optical fields

The non-classical feature of sub-Poissonian photon statistics is extended from one- to two-mode electromagnetic fields, incorporating the physically motivated property of invariance under passive unitary transformations. Applications to squeezed coherent states, squeezed thermal states, and superposition of coherent states are given. Dependences of extent of non-classical behaviour on the independent squeezing parameters are graphically displayed