Method for regulating the working point of a modulator and associated drive unit
AssigneeSiemens Aktiengesellschaft
InventorsHarald Geiger, Georg Mohs, Christoph Glingener
Life of this patent
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Abstract
A method and drive unit for controlling a modulator (128) in which the working point of the modulator (128) is regulated using a regulating circuit (124) in such a way that the working point is stable in relation to the transmission characteristic curve of the modulator (128) for a long time and under different operating conditions.
Claims19
A method for regulating the working point of a modulator which generates a modulated output radiation from an input radiation as a function of a control signal, the method comprising the steps of:
- sensing an average radiant power from the output radiation in at least one predefined frequency range;
- forcing a periodic deflection of the working point with a working point deflection frequency;
- generating a working point regulating signal as a function of the deflection of the working point;
- changing an average value of the control signal as a function of the regulating signal;
- and
- regulating a derivative of the function of the deflection of the working point and a sensed capacity as a regulated variable, reference being made to a point of the function at which the derivative has a value zero.
A drive unit for regulating the working point of a modulator, comprising:
- a transducer unit which generates, as a function of an output radiation of a modulator, an output signal whose signal value is a measure of an average radiant power;
- a working point deflection unit which periodically deflects the working point in accordance with a deflection frequency;
- a working point regulating unit which generates a regulating signal for regulating the working point as a function of the output signal of the transducer unit and as a function of the deflection of the working point;
- and
- a setting unit which changes as a function of the regulating signal one of an average value of a modulator control signal and a signal value of an auxiliary signal which influences the average value of the control signal;
- wherein the regulating unit comprises:
- a low-frequency signal generator which generates an alternating signal;
- a multiplication unit connected downstream of the signal generator and downstream of one of a power meter and a photo-element which is connected downstream of the bandpass filter;
- a low-pass filter unit connected downstream of the multiplication unit and which transmits only signals with a frequency lying below a limiting frequency;
- an integrator unit connected downstream of the low-pass filter unit and which generates at its output a signal which is proportional to a time integral of a signal at its input;
- and
- an adder unit connected downstream of the integrator unit and the signal generator which adds signal values present at its inputs.
Dependencies are inferred from the claim text.