US 2004/0165622 A1Published application

Statistic parameterized control loop for compensating power and extinction ratio of a laser diode

OwnerCheng Youn Luinventor

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Abstract

An automatic closed loop power control system is described for simultaneously adjusting an output power and an extinction ratio P1/P0 of a laser diode in order to maintain a desired average output power and a desired extinction ratio. The bias current component of a laser diode drive current is adjusted to compensate for changes in the average output power caused by ambient characteristics such as temperature and aging. Simultaneously, a modulation current component of the laser diode drive current is adjusted to maintain an extinction ratio of the laser diode output signal. The bias current and modulation current adjustments are based on the second order statistics of an average output power of the laser diode and a variance in the power output of the laser diode.

Claims17

Dependent claims

An automatic power control system for simultaneously adjusting an output power and an extinction ration of a laser diode comprising:

bias current determination logic including
logic for determining an average power difference between a current
measurement of an output power of the laser diode and a reference average output power, and
a first integrator communicatively coupled to receive the determined average power difference from the logic, the first integrator summing the determined average power difference with a determined average power difference based on at least one previous measurement resulting in a bias current output signal;
and
modulation current determination logic including
a nonlinear processing block including logic for determining an absolute value of the current measurement adjusted by a nonlinear estimation reference constant,
logic, communicatively coupled to the nonlinear processing block for determining a power variance difference between the determined absolute value and a reference power output variance proportional to an extinction ratio P1/P0 for reference power levels P1 and P0 wherein P1 represents a digital one value and P0 represents a digital zero value, and
a second integrator, communicatively coupled to receive the variance difference from the logic, the second integrator summing the determined variance difference with a determined power variance difference for at least one previous measurement resulting in a modulation current output signal.

6 more elements

A method for maintaining a laser output signal about a reference average output power and about a reference extinction ratio comprising:

determining a bias current and a modulation current of a laser diode drive current for a reference P1 power level and for a reference P0 power level;
determining a reference average power and a reference power variance based upon the reference power levels P1 and P0;
and
adjusting the bias current and the modulation current simultaneously for maintaining about the reference average power and about the reference extinction ratio.

1 more element

A system for maintaining a laser output signal about a reference average output power and about a reference extinction ratio comprising:

means for determining a bias current and a modulation current of a laser diode drive current for a reference P1 power level and for a reference P0 power level;
means for determining a reference average power and a reference power variance based upon the reference power levels P1 and P0;
and
means for adjusting the bias current and the modulation current simultaneously for maintaining about the reference average power and about the reference extinction ratio.

1 more element

Dependencies are inferred from the claim text.