| 摘要 |
A bidirectional optical coupler has a single optical fibre link between two transceivers. Each transceiver includes a holographic optical element (HOE), equivalent to a combination of lenses and a beam splitter; a source of monochromatic radiation; and a photodetector responsive to the radiation. Within a transceiver in the transmit mode, a divergent beam of radiation from the source is incident upon the HOE, and is diffracted, to form a pattern of interference fringes. Radiation is apparently focussed on the adjacent end of the optical fibre, and is transmitted by the fibre. At the other end of the optical fibre, the transceiver is in the receive mode, and the transmitted radiation is emitted as a divergent beam from the fibre, to be incident upon the HOE. The radiation is diffracted, and forms two angularly separated patterns of interference fringes. Thus, the radiation is apparently focussed upon the photodetector, (and upon the angularly separated, inoperable source). |
