Abstract: In coupling a control station 11 transmitting a radio signal to a plurality of base stations each transmitting the radio signal to a terminal station by an optical fiber, and dependently connecting the plurality of base stations to the optical fiber, the control station 11 includes a radio signal transmitter 16 and an electrical-to-optical converter 17, each of the base stations 12 includes an SOA-EAM 18 comprises a semiconductor optical amplifier (SOA) and an electro-absorption modulator (EAM), a down link radio signal amplifier 19, and a down link antenna 20, the SOA-EAM 18 receiving an optical signal from the control station 11. It is possible to provide an optical transmission system which can prevent optical power from lowering even if the number of base stations increases and which can facilitate adding a base station since an optical coupler is not used.

Abstract: A self-locking nut mechanism is operable to be mounted on a bolt element to secure structural members together and includes a nut body having a cylindrical portion and a flange portion. A through hole in the nut body has a first hole portion with one diameter and a second hole portion with another larger diameter, the nut body having a transition section between the first and second hole portions with such transition section having a first tapered part. A split nut is disposed in the second hole portion, the split nut being split into at least two split-nut sections. The split nut has a longitudinal end having a second tapered part. A spring in the nut body biases the split-nut toward the first tapered part such that the first and second tapered parts are biasingly engaged. The bolt element has external fastenings, and the split-nut has internal fastenings.