multiplexing system is proposed and demonstrated. The device, which consists of a tapered
directional coupler and two output bend waveguides, has a 50: 50 coupling ratio around the
wavelength of 1550 nm for both fundamental and first order transverse magnetic (TM0 and
TM1) modes. Based on asymmetrical tapered structure, a short common coupling length of~
15.2 μm for both modes is realized by optimizing the width of the tapered waveguide. The …