Arrangement for controlling or regulating an emission wavelength and emitted power of a semiconductor laser

• US 4,815,081 A
• Filed: 03/23/1988
• Issued: 03/21/1989
• Est. Priority Date: 03/30/1987
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Schienle, Meinrad, Maerz, Reinhard, Mahlein, Hans
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US07/172,234
• Time in Patent Office: 363 Days
• Field of Search: 372/32, 372/19, 372/43, 372/20, 372/31, 372/29, 358/60
• US Class Current: 372/32
• CPC Class Codes: H01S 5/0264 for monitoring the laser-output
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser

Abstract

An arrangement for controlling or regulating the emission wavelength and emitted optical power of a semiconductor laser is provided in optically integrated fashion. The optical power of the laser is at least partially supplied to an optical detector device and to a wavelength selective optical filter device. That part of the supplied power which passes through the filter device is conducted to another opto-electrical detector device. As a result of the two diodes, the optical power and the emission wavelength of the laser are simultaneously measured, whereby two control signals for the injection current of the laser are obtained.

Claims

1. An arrangement for controlling or regulating an emission wavelength and emitted optical power of a semiconductor laser, comprising:

first and second opto-electrical detector devices;

a wavelength selective optical filter device;

means for conducting at least part of said optical power of said semiconductor laser to said first opto-electrical detector device and said wavelength-selective optical filter device; and

means for supplying a part of said emitted optical power to said second opto-electrical detector device, said part of said emitted optical power being reflected from or permitted to pass by said wavelength selective optical filter device.

2. An arrangement as claimed in claim 1, wherein said wavelength selective optical filter device has a transmission curve having a change over a defined wavelength region into which said emission wavelength falls.

3. An arrangement as claimed in claim 2, wherein said transmission curve of said wavelength selective optical filter device has a peak in said defined wavelength region.

4. An arrangement as claimed in claim 3, wherein said peak of said transmission curve of said wavelength selective optical filter device corresponds to at least a relative transmission maximum.

5. An arrangement as claimed in claim 1, wherein said wavelength selective optical filter device is composed of at least one optical filter element.

6. An arrangement as claimed in claim 5, wherein said at least one optical filter element is a plurality of individual optical filter elements disposed successively in a propagation direction of said optical power.

7. An arrangement as claimed in claim 6, wherein said plurality of individual optical filter elements are Bragg gratings.

9. An arrangement as claimed in claim 5 wherein said at least one optical filter element is a Bragg grating.

10. An arrangement as claimed in claim 7, wherein said Bragg grating has a varying grating constant. constant.

11. An arrangement as claimed in claim 5, wherein said at least one optical filter element of said wavelength selective optical filter device comprises first and second Bragg gratings disposed successively in a propagation direction of said optical power, said first and second Bragg gratings being spaced from one another by a distance substantially equaling a whole multiple of half an optical wavelength of said optical power.

12. An arrangement as claimed in claim 1, wherein said wavelength selective optical filter device is a directional coupler.

13. An arrangement as claimed in claim 12, wherein said directional coupler is a co-directional directional coupler.

14. An arrangement as claimed in claim 12, wherein said directional coupler is a contra-directional directional coupler.

15. An arrangement as claimed in claim 1, wherein said wavelength selective optical filter device is an interference filter.

16. An arrangement as claimed in claim 1, wherein said wavelength selective optical filter device is a first optical filter device, and further comprising:

at least a second optical filter device disposed side-by-side with said first optical filter device;

means for supplying portions of said optical power in parallel to said first and said at least second optical filter devices;

a different one of said opto-electrical detector devices allocated to each of said first and said at least second optical filter devices; and

means for conducting parts of said supplied portions of said optical power to said different ones of said opto-electrical detector devices, said parts of said supplied portions being reflected from or permitted to pass by allocated ones of said first and said at least second optical filter devices.

17. An arrangement as claimed in claim 16, wherein said first and said at least second optical filter devices have different transmission curves having changes in different wavelength regions that follow one another in a direction of increasing wavelength.

18. An arrangement as claimed in claim 17, wherein said different wavelength regions of said optical filter devices are at least adjacent one another.

19. An arrangement as claimed in claim 18, wherein said different wavelength regions of said optical filter devices overlap one another.

20. An arrangement as claimed in claim 1, wherein said first opto-electrical detector device is partially transmissive so that a transmitted part of said part of said optical power conducted to said first detector device by said means for conducting is passed through said first detector device;

and

second means for conducting said transmitted part to said wavelength selective optical filter device.

21. An arrangement as claimed in claim 20, wherein said semiconductor laser emits optical power to two sides, part of said optical power from one of said two sides being taken as output power, and said arrangement being connected to receive part of said optical power from a second of said two sides.

23. An arrangement as claimed in claim 20, wherein at least said second detector device is transmissive, and

means for taking out power from said transmissive second detector device.

24. An arrangement as claimed in claim 1, wherein said semiconductor laser emits optical power to two sides, part of said optical power from one of said two sides being taken as output power, and said arrangement being connected to receive part of said optical power from a second of said two sides.

25. An arrangement as claimed in claim 1, further comprising:

at least one optical waveguide conducting said optical power to said filter device and said detector devices.

26. An arrangement as claimed in claim 25, wherein said detector devices are photodiodes, said at least one optical waveguide is a strip waveguide, and

said semiconductor laser and said filter device and said detector devices and said strip waveguide are integrated on a common substrate.

27. An arrangement as claimed in claim 25 wherein said at least one waveguide is a branched waveguide, and further comprising:

a first waveguide branch of said branched waveguide connected to receive said output power from said semiconductor laser;

a second waveguide branch of said branched waveguide conducting a second wavelength to one of said detector devices, said second wavelength differs from said emission wavelength; and

a second filter device preceding said one detector device, said second filter device blocking said emission wavelength and passing said second wavelength.

28. An arrangement as claimed in claim 27, wherein said branched waveguide is a forked strip waveguide.

29. An arrangement as claimed in claim 1, wherein said first detector device produces a first output signal which is connected to control or regulate said emitted power of said semiconductor laser;

said second detector device producing a second output signal; and

further comprising;

a amplifier connected to receive said first and second output signals, said amplifier providing an amplifier output signal which is proportional to a quotient of said first and second output signals, said amplifier output signal connected to control said emission wavelength of said semiconductor laser.

30. An arrangement as claimed in claim 29, further

a variable voltage divider device connected between one of said first and second detector devices and said amplifier.

31. An arrangement as claimed in claim 30, further comprising:

an inverter connectable between another one of said first and second detector devices and said amplifier.

32. An arrangement as claimed in claim 29, further comprising:

an inverter connectable between one of said first and second detector devices and said amplifier.

8. An arrangement as claimed in claim 8, wherein at least one of said Bragg gratings have a varying grating constant.

22. An arrangement as claimed in claim 22, wherein said partially transmissive detector device absorbs more than 95% of optical power conducted to it.