US 4,792,956 A · Laser diode intensity and wavelength control

Abstract

The actual values of intensity and wavelength of the optical signal output from a laser diode are compared to desired values thereof to generate intensity and wavelength error signals. The rates of change of the wavelength and intensity as functions of temperature and injection current about nominal operating values of the temperature and injection current are determined and used to calculate an injection current error signal and a temperature error signal for adjusting the injection current and temperature, respectively. The time response of the injection current and temperature are decoupled, which allows independent adjustment of the time constants of the exponential expressions for injection current and temperature. Providing independent adjustment of the time constants of the injection current and temperature variations permits the desired signal wavelength and intensity to be obtained in a time efficient manner.

Claims8

Dependent claims

A method for simultaneously controlling the intensity and wavelength of an optical signal output from a laser diode, comprising the steps of:

sensing the intensity of the optical signal;
comparing a desired value of the intensity to the sensed intensity to produce an intensity error signal;
sensing the wavelength of the optical signal;
comparing a desired value of the wavelength to the sensed wavelength to produce a wavelength error signal;
multiplying the wavelength error signal by a first numerical factor and a second numerical factor;
multiplying the intensity error signal by a third numerical factor and a fourth numerical factor;
adding the product of the wavelength error signal and the first numerical factor to the product of the intensity error signal and the third numerical factor to produce a temperature variation signal;
adding the product of the wavelength error signal and the second numerical factor to the product of the intensity error signal and the fourth numerical factor to produce an injection current variation signal;
adjusting the temperature of the laser diode as a function of the temperature variation signal;
and
adjusting the injection current of the laser diode as a function of the injection current variation signal.

8 more elements

A system for simultaneously controlling the intensity and wavelength of an optical signal output from a laser diode, comprising:

means for sensing the intensity of the optical signal;
means for comparing a desired value of the intensity to the sensed intensity to produce an intensity error signal;
means for sensing the wavelength of the optical signal;
means for comparing a desired value of the wavelength to the sensed wavelength to produce a wavelength error signal;
means for multiplying the wavelength error signal by a first numerical factor and a second numerical factor;
means for multiplying the intensity error signal by a third numerical factor and a fourth numerical factor;
means for adding the product of the wavelength error signal and the first numerical factor to the product of the intensity error signal and the third numerical factor to produce a temperature variation signal;
means for adding the product of the wavelength error signal and the second numerical factor to the product of the intensity error signal and the fourth numerical factor to produce an injection current variation signal;
means for adjusting the temperature of the laser diode as a function of the temperature variation signal;
and
means for adjusting the injection current of the laser diode as a function of the injection current variation signal.

8 more elements

A system for simultaneously controlling the intensity and wavelength of an optical signal output from a laser diode, comprising:

means for sensing the intensity of the optical signal;
means for sensing the wavelength of the optical signal;
means for comparing the selected value of the intensity to the sensed intensity to produce an intensity error signal determining time variations of the laser diode injection current from a value of the injection current that corresponds to a selected intensity and a selected wavelength of the optical signal output from the laser diode;
means for comparing the selected value of the wavelength to the sensed wavelength to produce a wavelength error signal;
means for determining time variations of the laser diode operating temperature from a value of the operating temperature that corresponds to a selected intensity and a selected wavelength of the optical signal output from the laser diode;
means for decoupling variations in the injection current as a function of time from variations in operating temperature as a function of time;
means for producing a temperature variation signal that is a function of the wavelength and intensity error signals;
means for producing an injection current variation signal that is a function of the wavelength and intensity error signals;
means for adjusting the temperature of the laser diode as a function of the temperature variation signal;
means for adjusting the injection current of the laser diode as a function of the injection current variation signal;
and
means for adjusting the injection current and operating temperature independently of one another to maintain the intensity and wavelength of the signal output from the laser diode within predetermined limits of selected values thereof.

9 more elements

Dependencies are inferred from the claim text.

Laser diode intensity and wavelength control

Life of this patent

Laser diode intensity and wavelength control

Life of this patent

Abstract

Claims8