An optical connector comprises a ring-shaped waveguide and a straight waveguide for introducing a light beam into the waveguide. These waveguides are arranged on a substrate in a manner such that the gap between their nearest positions is not longer than the wavelength of the light beam. The radius, width, thickness, and refractive index distribution of the ring-shaped waveguide are set so that a light beam with a wavelength .lambda.=2.pi.r/n (r and n are the radius of the ring-shaped waveguide and a certain natural number, respectively) continues to circulate therein. A grating having a cycle of 2.pi.r.lambda./(2.pi.r+.lambda.) or 2.pi.r.lambda./(2.pi.r-.lambda.] is formed on the surface of the ring-shaped waveguide.