Abstract
Single and entangled photons, in particular, have now played an important role in quantum physics. They are the most important cornerstone to realize quantum computers and quantum cryptography. It is therefore necessary to develop high-efficiency entangled photon source for studying quantum optics. Although high efficiency entangled photon pairs have been demonstrated, they are often achieved with cavity and pulsed lasers. When not using the above method, the highest reported detection rate of entangled photon pairs is about 900 (1/s/mW). We use continuous wave laser which wavelength is 532nm, focused into a nonlinear optical crystal (KTP crystal). We observed a highly efficient entangled photon pairs with a detection rate up to 26675 (1/s/mW). These entangled photon pairs are of Type II Spontaneous parametric down-conversion, with wavelengths of 1038nm and 1091.2nm. In addition, we use various methods to measure their intensity correlation and to explore their properties, including biphoton rate, anticorrelation parameter, spectrum and Franson Interference.