An arrayed waveguide, a display device, and a spectacles device are disclosed. The arrayed waveguide includes a first waveguide layer and a second waveguide layer stacked. The first waveguide layer includes a first main expanding portion having a plurality of first optical medium layers configured to expand, in the first direction, the first light beam incident into the first main expanding portion and reflect it towards the second waveguide layer. The second waveguide layer includes a second main expanding portion having a plurality of second optical medium layers configured to expand, in the second direction, the second light beam incident into the second main expanding portion and reflect it to exit from a side of the second waveguide layer away from the first waveguide layer. The second main expanding portion is further configured to transmit the expanded first light beam therethrough.