Coherent light generators – Particular component circuitry – Having feedback circuitry
Reexamination Certificate
1999-01-11
2001-10-09
Arroyo, Teresa M. (Department: 2881)
Coherent light generators
Particular component circuitry
Having feedback circuitry
C372S029010
Reexamination Certificate
active
06301280
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to the field of wavelength stabilized laser systems.
DESCRIPTION OF THE RELATED ART
The wavelength stabilized laser is a recently developed component of dense wavelength division multiplexed (DWDM) systems. In a DWDM system, a single semiconductor laser device may be used to provide light at several predetermined wavelengths (each corresponding to a different channel.) Commercial devices have been produced with 100 gigahertz spacing. If it becomes necessary to add further channels to an existing optical fiber, even denser wavelength spacing may be used in the future. As the wavelength spacing decreases, wavelength stabilization takes on a more important role.
U.S. Pat. No. 5,832,014 to Johnson, which is assigned to Lucent Technologies Inc., is incorporated herein by reference in its entirety for its teachings on wavelength stabilization in tunable semiconductor lasers.
It is common to include a filter in a feedback control loop for the laser device. The filter has a gain that varies with the wavelength of the laser light. A first photodetector measures the laser light before the light enters the filter, and a second photodetector measures the filtered light exiting the filter. A high gain differential amplifier provides an amplified difference signal proportional to the difference between the output of the first photodetector and the output of the second photodetector. The amplified difference signal is used to control the laser wavelength (by adjusting a temperature controller or a bias signal that is transmitted to the laser).
The differential amplifier is an active component that may exhibit temperature dependencies, aging or other disadvantages. A method for overcoming these disadvantages is desired.
SUMMARY OF THE INVENTION
The invention is a system and method for controlling, a laser. The amplitude of a laser light output by the laser is detected. The laser light is filtered and a filtered light is output. The filtered light has an amplitude that varies with the wavelength of the laser light. The amplitude of the filtered light is detected. Signals representing the amplitude of the laser light and the amplitude of the filtered light are provided to a primary of a transformer. The wavelength of the laser is controlled based on a voltage of the secondary of the transformer.
REFERENCES:
patent: 4901306 (1990-02-01), Gardner
patent: 4912526 (1990-03-01), Iwaoka et al.
patent: 4914662 (1990-04-01), Nakatani et al.
patent: 5084884 (1992-01-01), Terada
patent: 5099144 (1992-03-01), Sai
patent: 5384799 (1995-01-01), Osterwalder
patent: 5428700 (1995-06-01), Hall
patent: 5764678 (1998-06-01), Tada
patent: 5786915 (1998-07-01), Scobey
patent: 5832014 (1998-11-01), Johnson
patent: 6134253 (2000-10-01), Munks
Tidrow et al., “A high strain two-stack two-color quantum well infrared photodetector”, Appl. Phys. Lett. 70(7):859-861, Feb. 1997.
Chen et al., “Two-color corrugated quantum-well infrared photodetector for remote temperature sensing”, Appl. Phys. Lett. 72(1):7-9, Jan. 1998.
1998 Santec Component Series, pp. 1-11.
Wavelength-Selected (D2526G) Laser 2000 Direct Modulated Isolated DFB Laser Module, Lucent Technologies, Bell Labs Innovations, Aug. 1997, pp. 1-8.
Wavelength Locker Test Report, JDS Fitel, Dec. 4, 1997, pp. 1-3.
Nortel Networks: Optical Networking/Transport, Nov. 18, 1998, pp. 1-3.
Broadband: Product Portfolio—Utility Networks, Nortel, Nov. 18, 1998, pp. 1-2.
News Letter, 32ch Tunable Laser Light Source System, Nov. 18, 1998, p. 1.
New Letter, Optical Variable Attenuator, OVA-630, Nov. 18, 1998, p. 1.
Components for DWDM Systems, Santec, Laser Focus World, Oct. 1998, p. 70.
Broutin Scott L.
Plourde James Kevin
Stayt, Jr. John William
Agere Systems Optoelectronics Guardian Corp.
Arroyo Teresa M.
Duane Morris & Heckscher LLP
Inzirillo Gioacchino
Koffs Steven E.
LandOfFree
Apparatus and method for forming a laser control signal, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for forming a laser control signal, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for forming a laser control signal, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584534