| 摘要 |
An optical modulator comprises a bi-moded fibre (2) for supporting first and second different optical transmission modes, coupled between input and output single mode fibres (1, 3). The two modes in the bi-moded fibre (2) interfere and the intensity of the radiation that passes to the single mode output fibre (3) is a function of the relative phases of the first and second modes. The bi-moded fibre (2) is electrically poled and is provided with modulating electrodes (19, 20). When a modulating voltage from a modulating source (V) is applied to the electrodes, the refractive index of the waveguide for the first transmission mode is altered relative to the refractive index of the waveguide for the second mode such as to change the phase difference between the modes at the entrance to the output fibre (3) so as to control the intensity of optical radiation that passes through the output fibre (3). <IMAGE> |
