“…In recent years, various multi-port output beam splitters have been proposed, such as even-port beam splitter [6][7][8][9], odd-port output beam splitter [10][11][12], and polarization selective beam splitter [13,14]. Among them, the three-port beam splitter has the features of simple structure and large manufacturing tolerance, so it is widely used in pulse detection [15], sensors [16][17][18][19][20][21], signal processing [22][23][24], and photonic crystal fabrication [25,26]. Therefore, it is necessary to propose an efficient three-port diffraction beam splitter.…”