Optical waveguide module and method for coupling optical signal

The invention provides an optical waveguide module and a method for coupling an optical signal, which can be applied to the field of optical display. The optical waveguide module comprises a first coupling-in grating, a waveguide and a second coupling-in grating, the sum of the width of the first coupling-in grating and the width of the second coupling-in grating is a first preset value, and the incident light signals comprise a first incident light signal and a second incident light signal. Wherein the first coupling-in grating is positioned on the upper surface of the waveguide and is used for coupling a first incident light signal into the waveguide; the second coupling-in grating is located on the lower surface of the waveguide and used for coupling a second incident light signal into the waveguide; the waveguide is used for reflecting the first incident light signal to obtain a first reflected light signal, transmitting the first reflected light signal, reflecting the second incident light signal to obta