Patent ID: 7212745

Claim:
An optical transmission system comprising: a transmitter for transmitting an optical signal toward a multi-mode fiber having an input plane with a core diameter, said transmitter including: a light emission element for generating an optical signal; and at least one lens having an optical axis and a vertex for converging the optical signal generated by said light emission element, wherein the optical signal converged by said at least one lens enters the input plane of the multi-mode fiber to propagate through the multi-mode fiber, the optical axis is aligned with a fiber axis of the multi-mode fiber, the vertex is located at a predetermined distance from the input plane of the multi-mode fiber, the predetermined distance is greater or less than a distance from the vertex to a focal point of said at least one lens, an incident light propagation cross-section of the optical signal is defined in a plane perpendicular to the optical axis at the predetermined distance from the vertex, and a distance between the focal point and the input plane is such that the incident light propagation cross-section is greater than a core cross-section defined by the core diameter at the input plane; and a receiver including a light receiving element for receiving the optical signal outputted from the multi-mode fiber.