In order to diminish the crosstalk and power loss of asymmetric X-junction coupler and increase the angle of asymmetric area for separating mode

an improved design of asymmetric X-junction coupler is proposed. The beam propagation method and effective index method are used to simulate and analysis the crosstalk and power loss of improved asymmetric X-junction coupler. The result shows that the crosstalk of improved X-junction has been greatly diminished and the power loss has been ameliorated.