Patent ID: 7403551

Claim:
A device for regulating a laser diode that emits a light which correlates with the sum of a direct current (I BIAS ) and a pilot signal (I LDAC ), the direct current (I BIAS ) correlating with optical properties of the laser diode, the laser diode having a threshold current (I th ), the device comprising: a driver for regulating the direct current (I BIAS ), a monitor device that converts the light into a monitor current (I MD ) having a DC measurement signal (I MDdc ) correlating with the direct current (I BIAS ) and an AC signal (I MDac ) correlating with the pilot signal (I LDAC ), means for calculating a differential current (I diff ) defined by a difference between the direct current (I BIAS ) and the threshold current (I th ) or a variable correlating with the differential current (I diff ), and means for regulating the differential current (I diff ) or the variable correlating with the differential current (I diff ) to a constant value or a value which is only dependent on temperature, the means for regulating comprising: integration means which integrates a mixed signal comprising the AC signal and the pilot signal (I LDAC ) to form an AC measurement signal (I MDac ) correlating with the amplitude of the AC signal (I MDac ); and a regulator which multiplies the ratio of the DC measurement signal (I MDdc ) to the amplitude of the AC measurement signal (I MDac ) by the amplitude of the pilot signal (I LDAC ) to obtain a result and compares the result with a constant value of the differential current (I diff ) or a variable derived therefrom which characterizes the operating point, for the evaluation and which, in a manner dependent on this comparison, regulates or controls the direct current (I BIAS ) in such a way that the result and the constant value or the derived variable essentially correspond.