Optical system with bright light output

• US RE33,722 E
• Filed: 08/15/1990
• Issued: 10/22/1991
• Est. Priority Date: 04/28/1987
• Status: Expired due to Term

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Spectra Diode Laboratories, Inc.
• Inventors: Scifres, Donald R., Worland, D. Philip
• Primary Examiner(s): ULLAH, AKM E
• Application Number:
  US07/568,587
• Time in Patent Office: 433 Days
• Field of Search: 350/96.15, 350/96.24, 372/6, 372/22, 372/27, 372/34
• US Class Current: 385/33
• CPC Class Codes: G02B 6/2552 reshaping or reforming of light guides for coupling using thermal heating, e.g. tapering, forming of a lens on light guide ends
• CPC Class Codes: G02B 6/262 Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
• CPC Class Codes: G02B 6/2808 using a mixing element which evenly distributes an input signal over a number of outputs
• CPC Class Codes: G02B 6/2856 formed or shaped by thermal heating means, e.g. splitting, branching and/or combining elements
• CPC Class Codes: G02B 6/4203 Optical features
• CPC Class Codes: G02B 6/425 Optical features semiconductor laser arrays H01S5/40; hybrid LED arrays H01L25/0753; monolithic LED arrays H01L27/153
• CPC Class Codes: H01S 3/094053 Fibre coupled pump, e.g. delivering pump light using a fibre or a fibre bundle
• CPC Class Codes: H01S 3/094057 by tapered duct or homogenized light pipe, e.g. for concentrating pump light
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence
• CPC Class Codes: H01S 5/4031 Edge-emitting structures
• CPC Class Codes: H01S 5/4062 with an external cavity or using internal filters, e.g. Talbot filters

Abstract

An optical system producing bright light output for optical pumping, communications, illumination and the like in which one or more fiberoptic waveguides receive light from one or more diode lasers or diode laser bars and transmit the light to an output end where it is focused or collimated into a bright light image. The input end of the fiberoptic waveguide may be squashed into an elongated cross section so as to guide light emitted from an elongated light source such as a diode laser bar. The waveguides are preferably arranged at the output end into a tightly packed bundle where a lens or other optical means focuses or collimates the light. For diode laser bars much wider than 100 microns, a plurality of waveguides may be arranged in a line to receive the light, and then stacked at the output in a less elongated configuration. In this manner, light from many diode lasers or laser bars may be coupled through the bundle into the end of solid state laser medium.

Claims

1. An optical system for producing a bright light output comprising,

a plurality of light sources, each of said light sources emitting light from a given emissive area with given lateral and transverse divergences,

a plurality of fiberoptic waveguides, each of said waveguides having an oblong input end and an output end, each oblong input end positioned relative to one of said light sources for accepting light therefrom, each oblong input end having core dimensions and lateral and transverse numerical apertures corresponding respectively to said emissive area and said lateral and transverse divergences of said one of said light sources so as to guide most of said light emitted by said light source, said fiberoptic waveguides being arranged at said output ends to form a bundle.

2. The system of claim 1 wherein each of said light sources is a diode laser.

3. The system of claim 1 wherein each of said light sources is a laser diode bar, each input end of said waveguides having an oblong core with a width at least as great as that of said laser diode bar.

4. The system of claim 1 wherein each light source is a pulsed laser.

5. The system of claim 4 wherein said light sources are operated serially such that the total light intensity from all of said light sources is substantially constant in time.

6. The system of claim 1 wherein each light source is a continuous wave laser.

7. The optical system of claim 1 further comprising optical means in proximity to each output end of said bundle of waveguides for focusing said light into a bright light image.

8. The system of claim 7 wherein said optical means couples said light into an end of a solid state active medium in a resonant optical cavity.

9. The system of claim 8 wherein said optical means is a focusing lens between the output ends of said bundle of waveguides and an end of said medium, the lens matching said light to a desired mode of said resonant optical cavity.

10. The system of claim 8 wherein said optical means is butt coupling said bundle to an end of said medium.

11. The system of claim 1 wherein said waveguides are arranged in a substantially circular cylindrical bundle of hexagonal-close-packed waveguides.

12. The system of claim 1 wherein said input end of said waveguide has a curved lens surface.

13. The system of claim 1 wherein the output ends of said waveguides terminate in a bead with a curved lens surface.

14. The system of claim 1 wherein the output end of said bundle is fused to form a homogeneous mixing rod.

15. The system of claim 1 wherein the output end of said bundle is tapered to a smaller diameter than the bundle diameter.

16. The system of claim 1 wherein a homogeneous mixing rod is butted to the output end of said bundle of waveguides.

17. The system of claim 16 wherein a partially reflecting mirror is disposed on an end of the mixing rod.

24. The system of claim 1 wherein said oblong input end of each of said fiberoptic waveguides is rectangular. .Iaddend. .Iadd.25. The system of claim 18 wherein said oblong input end of each of said fiberoptic waveguides is rectangular. .Iaddend. .Iadd.26. The system of claim 22 wherein said oblong input end of each of said fiberoptic waveguides is rectangular. .Iaddend. .Iadd.27. An optical system for producing a bright light output comprising:

a plurality of light sources, each of said light sources emitting light from a given emissive area with given lateral and transverse divergences,

a plurality of fiberoptic waveguides, each of said waveguides having an oblong input end and an output end, each oblong input end positioned relative to one of said light sources for accepting light therefrom, each oblong input end having core dimensions corresponding to said emissive area and a numerical aperture capable of guiding most of said light emitted by said light source, said fiberoptic waveguides being arranged at said output ends to form a bundle. .Iaddend. .Iadd.28. The system of claim 27 wherein said oblong input end of each of said fiberoptic waveguides is rectangular. .Iaddend. .Iadd.29. The system of claim 27 wherein said numerical aperture of each input end corresponds to the larger of said lateral and transverse divergences of said one of said light sources.

18. An optical system comprising,

a laser diode bar emitting a plurality of light elements from an oblong emissive area having a width and a height, the light elements radiating with characteristic lateral and transverse divergences, the emissive area being divided into a plurality of segments, each segment having at least one light element,

a plurality of fiberoptic waveguides, each of said waveguides having an oblong input end and an output end, the oblong input end of each waveguide being positioned relative to said laser diode bar for guiding light elements from one of said segments, the elongated input end of each waveguide having core dimensions and lateral and transverse numerical apertures corresponding respectively to a segment and said characteristic lateral and transverse divergences so as to guide most of said light emitted from said segment, said waveguides being arranged at said output end to form a bundle.

19. The optical system of claim 18 further comprising,

optical means in proximity to said output ends of said bundle of waveguides for coupling said light elements into an end of a solid state active medium in a resonant optical cavity.

20. The system of claim 19 wherein said optical means is a focusing lens between said output ends and said medium.

21. The system of claim 19 wherein said bundle is butt coupled to an end of said medium.

22. An optical system for producing a bright light output comprising,

a plurality of light sources, each of said light sources emitting light from a given emissive area with given lateral and transverse divergences,

a plurality of fiberoptic waveguides, each of said waveguides having an oblong input end and an output end, each oblong input end positioned relative to one of said light sources for accepting light therefrom, each oblong input end having core dimensions and lateral and transverse numerical apertures corresponding respectively to said emissive area and said lateral and transverse divergences of said one of said light sources so as to guide most of said light emitted by said light source, said fiberoptic waveguides being arranged at said output ends to form a bundle, and

optical means in proximity to each output end of partially reflecting a portion of said light emerging from said waveguides back into said waveguides thereby coupling said portion of said light into said light sources to induce coherent emission of said light sources.

23. The optical system of claim 22 wherein said waveguides are single mode waveguides. .Iadd.

25. Iaddend. .Iadd.30. An optical system comprising:

a laser diode emitting a plurality of light elements from an oblong emissive area having a width and a height, the light elements radiating wih characteristic lateral and transverse divergences, the emissive area being divided into a plurality of segments, each segment having at least one light element,

a plurality of fiberoptic waveguides, each of said waveguides having an oblong input end and an output end, the oblong input end of each waveguide being positioned relative to said laser diode bar for accepting light elements from one of said segments, the oblong input end of each waveguide having core dimensions corresponding to a segment and a numerical aperture capable of guiding most of said light emitted from said segment, said waveguides being arranged at said output ends to form a bundle. .Iaddend. .Iadd.31. The system of claim 30 wherein said oblong input end of each fiberoptic waveguide is rectangular. .Iaddend. .Iadd.32. The system of claim 30 wherein said numerical aperture of each waveguide corresponds to the larger of said lateral and transverse divergences of said light elements. .Iaddend. .Iadd.33. The system of claim 30 wherein said bundle has width and height dimensions such that the ratio of width to height of said bundle is less than the ratio of width to height of said emissive area of said laser diode bar. .Iaddend. .Iadd.34. The system of claim 30 further comprising optical means in proximity to said output ends of said bundle of waveguides for coupling said light elements into a solid state laser medium. .Iaddend.