  Field-orthogonal temporal mode analysis of optical fields is recently
developed for a new framework of quantum information science. But so far, the
exact profiles of the temporal modes are not known, which makes it difficult to
achieve mode selection and de-multiplexing. Here, we report a novel method that
measures directly the exact form of the temporal modes. This in turn enables us
to make mode-orthogonal homodyne detection with mode-matched local oscillators.
We apply the method to a pulse-pumped, specially engineered fiber parametric
amplifier and demonstrate temporally multiplexed multi-dimensional quantum
entanglement of continuous variables in telecom wavelength. The temporal mode
characterization technique can be generalized to other pulse-excited systems to
find their eigen modes for multiplexing in temporal domain.
