To provide a system suitable for connection of signals between an optical fiber and a device for generating or detecting the light signals.

The structure for connecting the optical fiber to the optical device has first and second surfaces intersecting nearly orthogonally with each other and has transmission and reception light propagation paths arranged between the first and second surfaces. The light propagation paths are respectively transparent optical members consisting of at least three pieces of segments. Each optical member includes of (a) first pair of input/output(I/O) ports, (b) a first pair of reflection mirrors, (c) a second pair of reflection mirrors and (d) a second pair of I/O ports. The second pair of the I/O ports described above are arranged on the second surface and have the inter-port spacing greater than the inter-port spacing of the first pair of the I/O ports.