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U.S. Department of Energy
Office of Scientific and Technical Information

Laser driver circuit with dynamic bias

Patent ·
OSTI ID:6475492
This patent describes a laser driver circuit for modulating the light output power of a laser between a desired predetermined low output power level and a high output power level in response to the zeroes and ones, respectively, of an input digital signal comprising: a photodetector for producing a feedback signal proportional to the light output of the laser, means for deriving a reference signal from the input digital signal, means for combining the photodetector feedback signal, the reference signal and a level setting input signal having a value determined by the desired predetermined low output power level of the laser, to produce an error signal proportional to the difference between the desired predetermined low output power level of the laser and the low output power level detected by the photodetector, and an integrating low frequency error amplifier responsive to the error signal for generating a bias current to the laser to maintain the low output power level at the desired predetermined value, characterized in that the laser driver circuit further comprises a variable gain amplifier connected between eth combining means and the error amplifier, the variable gain amplifier having a gain controlled by the input digital signal, the gain of the variable gain amplifier being a first value when the input digital signal is one and a second value when the input digital signal is zero.
Assignee:
Bell Communications Research, Inc., Livingston, NJ
Patent Number(s):
US 4796266
OSTI ID:
6475492
Country of Publication:
United States
Language:
English