| 摘要 |
A method of, and apparatus for, setting an operating (control) voltage of a voltage controllable optical component, such as a Mach-Zehnder optical modulator, having a periodic voltage/optical parameter (optical power) characteristic is described. The apparatus comprises: means (6, 7), up/down counter and D to A converter, operable to set the voltage (V) applied to the component to a predetermined initial value; means for measuring the optical parameter (P); means (5, 6) for sequentially progressively increasing and decreasing the voltage (incrementing/decrementing the counter) with respect to the predetermined value and means (5, 9, 10) for determining respective voltage values (V.infin. and V0 respectively) which produce maximum and minimum values of the optical parameter; and wherein the means (6, 7) operab le to set the voltage sets the voltage (V) to a value intermediate the maximum and minimum voltage values (V0 + V.infin.)/2). Further the apparatus compris es means (5) for determining the sense of the slope of that portion of the periodic characteristic lying between the said maximum and minimum values fo r use by a control loop during subsequent operation of the optical component.< /SDOAB>
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