Patent ID: 7469089

Claim:
A light receiving apparatus comprising: a tube waveguide having an optical waveguiding region arranged to propagate light entering an incident end and exiting an emission end of the tube waveguide through mirror reflection or total reflection; a light receiving device connected to the emission end of the tube waveguide to receive the light from the tube waveguide; and a multimode optical fiber arranged to transmit light into the optical waveguiding region of the tube waveguide from one end of the multimode optical fiber connected to the incident end of the tube waveguide; wherein an area of a cross sectional shape of the optical waveguiding region of the tube waveguide vertical to the propagating direction of light decreases gradually from the incident end to the emission end; a cross sectional shape of the optical waveguiding region vertical to a propagating direction of light is polygonal; and a size of the optical waveguiding region at a plane of the emission end of the tube waveguide is larger than a size of a light receiving plane of the light receiving device.