Laser diode control method and circuit
AssigneeU.S. Philips Corporation
InventorPaul Bathe
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Abstract
The operation of laser diodes requires a preset operating point. Owing to the spread in the characteristic curves of laser diodes, a costly adjustment is required for accurately determining this operating point, more specifically after each exchange of a laser diode. By using a control circuit, the operating point is positioned in the portion of the characteristic curve in which the ratio of the slope of the characteristic curve to the slope of the characteristic curve in the linear portion of the characteristic curve is equal to a predetermined value. This ratio is obtained by measuring the change in the bias current, which compensates for a power change caused by a change of the modulation current.
Claims16
A control method for a laser diode which comprises the steps of:
- providing a bias current for the laser diode;
- and
- directly determining a presettable operating point for the laser diode having a characteristic curve with a linear portion by evaluating the slope of the characteristic curve and setting the operating point at that point of the characteristic curve at which the slope is smaller than the slope in the linear portion of the characteristic curve.
Dependencies are inferred from the claim text.