| 摘要 |
An optical signal with optical frequency fc is applied to an electro- optic device (3) having drive electronics (2) employing sinusoidal electrical signals of frequency f0 and 2f0. The output of the device (3) is frequency upshifted to (fc + fo) or downshifted to (fc - fo) in dependence on electrical phases. The electro-optic device (3) includes three waveguide arms (6, 9, 12; 6, 10, 12; 7) of substantially identical optical length; EA and EB include sinusoidal signals of frequency f0, substantially in quadrature, whereas EC includes a sinusoidal signal of frequency 2f0. The basic device comprises an optical single sideband modulator, and it can be employed in a frequency division multiplexing optical communication system (Figs. 13 and 14). By adding a fourth (reference) waveguide arm (Fig. 6 or 7) it can be employed in an optical phase shifter (Fig. 10) or an optical phase or frequency modulator communication system (Fig. 11 or Fig. 12). <IMAGE>
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