The invention discloses a cascaded
waveguide-based end face coupler with a double-step structure. The cascaded
waveguide-based end face coupler is formed by cascading a first
waveguide and a second waveguide, introducing a
ridge waveguide on the first waveguide; the end surfaces of the
ridge waveguide and the first waveguide are flush to form an initial input end surface of the coupler, and the initial input end surface is completely matched with the size of the AWG output waveguide; the length of the
ridge waveguide is equal to that of the first waveguide, the width of the ridge waveguide is gradually reduced from the initial input end face to the output end face, and the projection of the ridge waveguide on the first waveguide is an
isosceles trapezoid; the second waveguide adopts a regular conical structure which is three-dimensionally reduced from the waveguide input end face to the waveguide output end face, the size of the second waveguide input end face is matched with that of the first waveguide output end face, the size of the output end face of the second waveguide is completely matched with that of the ridge waveguide of the photoelectric
detector, and the first waveguide, the second waveguide and the ridge waveguide are of a double-step structure. The coupler is small in size, low in loss, high in
error tolerance and capable of achieving efficient
coupling of waveguides of different sizes.