  Entangled state of light is one of the essential quantum resources in quantum
information science and technology. Especially, when the fundamental principle
experiments have been achieved in labs and the applications of continuous
variable quantum information in the real world are considered, it is crucial to
design and construct the generation devices of entangled states with high
entanglement and compact configuration. We have designed and built an efficient
and compact light source of entangled state, which is a non-degenerate optical
parametric amplifier (NOPA) with the triple resonance of the pump and two
subharmonic modes. A wedged type-II KTP crystal inside the NOPA is used for
implementing frequency-down-conversion of the pump field to generate the
optical entangled state and achieving the dispersion compensation between the
pump and the subharmonic waves. The EPR entangled state of light with quantum
correlations of 8.4 dB for both amplitude and phase quadratures are
experimentally produced by a single NOPA under the pump power of 75 mW.
