To relax the accuracy with respect to a positional deviation, and thus to reduce costs.
An optical waveguide and a light path adjuster are included, the optical waveguide performing propagation only in a reference mode at a first wavelength, the light path adjuster adjusting a light path such that input light is guided to a core of the optical waveguide. Communication is performed using light of a second wavelength that enables the optical waveguide to perform propagation in at least a first order mode in addition to the reference mode. When there is a positional deviation, input light that is not headed for the core of the optical waveguide is guided to the core due to the light path adjuster adjusting a path of the light. This results in a reduction in a loss of coupling of optical power. Further, propagation is performed by the optical waveguide in at least the first order mode in addition to the reference mode, the at least the first order mode being generated due to the light path adjuster adjusting a path of the input light. This results in a reduction in a loss of coupling of optical power. This makes it possible to relax the accuracy with respect to a positional deviation, and thus to reduce costs.