Dielectric waveguide-based multi-mode interference coupler and interferometer

A dielectric waveguide-based MMI coupler, comprising:

• a multi-mode waveguide, one end of the multi-mode waveguide is connected to M input channels and another end is connected to N output channels, wherein both M and N are positive integers;
• and
• a light absorber, comprising a waveguide cladding, an optical waveguide core and an absorbing material layer;
• the optical waveguide core and the absorbing material layer are surrounded by the waveguide cladding;
• wherein the optical waveguide core and the absorbing material layer are not directly connected with each other, the optical waveguide core comprises a first end and a second end, while a radial dimension of the optical waveguide core decreases gradually from the first end to the second end;
• wherein at least one end of the multi-mode waveguide has the light absorber arranged, and the first end of the optical waveguide core of the light absorber is connected to the end of the multi-mode waveguide where the light absorber is located;
• and
• a material of both the multi-mode waveguide and the optical waveguide core of the light absorber is a dielectric.