High power and high brightness diode-laser array for material processing applications

• US 20090190218A1
• Filed: 02/04/2009
• Published: 07/30/2009
• Est. Priority Date: 07/18/2006
• Status: Active Grant

• Current Assignee: Douglas William Anthon, Luis A. Spinelli, Sergei V. Govorkov, Sol Peter Dijaili
• Original Assignee: Douglas William Anthon, Luis A. Spinelli, Sergei V. Govorkov, Sol Peter Dijaili
• Inventors: Govorkov, Sergei V., Spinelli, Luis A., DiJaili, Sol Peter, Anthon, Douglas William
• Granted Patent: US 7,697,207 B2
• Time in Patent Office: Days
• US Class Current: 359/489.08
• CPC Class Codes: B23K 26/0613 having a common axis B23K26/0619 takes precedence
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/0071 for beam steering, e.g. using a mirror outside the cavity to change the beam direction
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/02326 Arrangements for relative positioning of laser diodes and optical components, e.g. grooves in the mount to fix optical fibres or lenses
• CPC Class Codes: H01S 5/0237 by soldering
• CPC Class Codes: H01S 5/02484 Sapphire or diamond heat spreaders
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4018 Lasers electrically in series
• 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 5/4043 with vertically stacked active layers
• CPC Class Codes: H01S 5/4056 emitting light in more than one direction
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength

Abstract

Arrangements for combination and fast-axis alignment of fast-axes of diode-laser beams are disclosed. Alignment arrangements include providing each diode-laser with a corresponding alignable fast-axis collimating lens, providing individually alignable mirrors for steering an re-orienting beams from each diode-laser, and providing single diode-laser slab-modules in which the diode-laser beams can be pre-aligned to a common propagation-axis direction, and in which edges and surfaces of the slabs can be used to align the fast and slow-axes of the beams. Beam combination methods include combination by dichroic elements, polarization-sensitive elements, and optical fiber bundles.

Claims

1. Optical apparatus, comprising:

a metal heat-sink; and

a plurality of diode-laser assemblies, each of the thereof including only one diode-laser and a thermally conductive electrically insulating sub-mount having first and second surfaces perpendicular to each other, the diode-laser characterized as having a fast-axis, a slow-axis perpendicular to the fast axis, and a propagation axis perpendicular to both the fast-axis and the slow axis, and being bonded to the first surface of the sub-mount; and

wherein each of the diode-laser assemblies is bonded via the second surface of the sub-mount thereof to the heat sink with the propagation axes of the diode-lasers being about parallel to each other and with fast-axes of the diode-lasers aligned in the fast-axis direction.

2. The apparatus of claim 1, wherein the insulating sub-mounts are diamond sub-mounts.

3. The apparatus of claim 1, further including a lens arranged to focus beams from the diode-lasers into a common focal spot.

4. The apparatus of claim 1, wherein the diode-lasers are electrically connected in series with each other.

5. Optical apparatus, comprising:

a plurality of pairs of diode-laser arrays, each diode-laser array including a plurality of diode-lasers, each diode-laser characterized as having a fast-axis, a slow-axis perpendicular to the fast axis, and a propagation axis perpendicular to both the fast-axis and the slow axis, with the diode-lasers in each of the arrays arranged, with propagation-axes thereof parallel to each other and with fast-axes of the diode-lasers aligned in the fast-axis direction, the diode-lasers in one array of each pair thereof having a different emitting wavelength from the diode-lasers in the other array of the pair, and the propagation axes of one diode-laser array in each pair being directed in a first direction, with the propagation axes of the other diode laser array in the pair being directed in a second direction at an angle to the first direction; and

wherein a wavelength-sensitive optical element cooperative with each pair is arranged to combine beams from the diode-lasers in each array of the pair in a common direction.

6. The apparatus of claim 5, wherein the wavelength sensitive optical element is a dichroic filter reflective for the emitting wavelength of lasers in one diode-laser array of the pair and transmissive for the emitting wavelength of diode-lasers in the other diode-laser array of the pair and the common direction is one of the first and second directions.

7. The apparatus of claim 5, wherein there are two pairs of diode-laser arrays with the combined-beam common directions of each pair being at an angle to each other.

8. The apparatus of claim 7, wherein the combined beams from each of the pairs of arrays are plane-polarized parallel to each other, wherein the apparatus further includes a polarization rotator arranged to rotate the polarization plane of one of the combined beams perpendicular to the polarization plane of the other, and wherein a polarization-sensitive optical device is arranged to combine the combined beams from the diode-lasers in each array of the pair in a common direction.

9. The apparatus of claim 8, wherein the combined beam directions of the pairs of arrays are perpendicular to each other and the polarization-selective device is a polarizing beamsplitter cube.

10. The apparatus of claim 7, wherein the combined beams from each of the pairs of arrays are plane-polarized perpendicular to each other, wherein the apparatus further includes a polarization-sensitive optical device arranged to combine the combined beams from the diode-lasers in each array of the pair in a common direction.

11. The apparatus of claim 10, wherein the combined beam directions of the pairs of arrays are perpendicular to each other and the polarization-selective device is a polarizing beamsplitter cube.

12. Optical apparatus, comprising:

a plurality of diode-laser array packages;

each of the diode-laser array packages including a plurality of laser diode-arrays;

each of the diode-laser arrays including a heat sink and a plurality of diode-laser assemblies, each of the thereof including only one diode-laser and a thermally conductive electrically insulating sub-mount having first and second surfaces perpendicular to each other, the diode-lasers characterized as having a fast-axis, a slow-axis perpendicular to the fast axis, and a propagation axis perpendicular to both the fast-axis and the slow axis, and being bonded to the first surface of the sub-mount, with each of the diode-laser assemblies being bonded via the second surface of the sub-mount to the heat sink, with the propagation axes of the diode-lasers being parallel to each other and with fast-axes of the diode-lasers aligned in the fast-axis direction;

each of the diode-laser array packages including an optical arrangement for combining beams from the diode-laser arrays such that the combined beams propagate parallel to each other and aligned in the diode-laser fast axis direction; and

each diode-laser package having an optical focusing element and an optical fiber associated therewith, with the focusing element arranged to focus the combined beams from the package into a proximal end of the optical fiber, with distal ends of all of the optical fibers are formed into a bundle.

13. The apparatus of claim 12, wherein there are seven diode-laser array packages and the bundle into which the distal ends of the optical fibers are formed is a hexagonal close-packed bundle.

14. Optical apparatus, comprising:

a thermally conductive metal base-plate having a mounting surface;

a plurality of individual diode-laser packages each thereof including only one diode-laser mounted on a heat sink, the packages being mounted on the mounting surface of the base via a thermally conductive but electrically insulating layer, each diode-laser having an emitting aperture from which a beam of laser radiation is emitted;

the packages being arranged in pairs thereof with diode-lasers thereof arranged face-to-face and spaced apart with the fast-axes of the diode-lasers parallel to the mounting surface of the heat sink, the packages being further arranged with propagation-axes of the diode-lasers parallel to each other, with the propagation-axes in one pair of packages opposed to the propagation-axes in the other, and interleaved such that beams emitted by the diode-lasers propagate about parallel to each other with adjacent ones thereof propagating in opposite directions with spacing between adjacent beams being less than the spacing between the diode-lasers in a pair of the packages;

a plurality of cylindrical lenses one thereof associated with each diode-laser, each cylindrical leans being arranged to collimate the beam emitted by the diode-laser in the fast-axis;

a plurality of mirrors mounted on the mounting surface of the base-plate each thereof associated with a corresponding one of the diode laser packages, the mirrors being arranged to reflect fast-axis collimated beams from the diode-lasers parallel to each other in the same direction perpendicular to the mounting surface of the base-plate with the fast-axes of the individual beams aligned in the fast-axis direction.

15. The apparatus of claim 14, wherein there are four diode-laser packages arranged in two pairs, with the diode-lasers in each pair about equally spaced part, wherein there are four mirrors, and wherein the spacing between the collimated, fast-axis-aligned beams reflected from the four mirrors, is about one-half of the spacing between diode-lasers in the pairs thereof.

16. Optical apparatus, comprising:

a thermally conductive metal base-plate having a mounting surface;

a plurality of individual diode-laser packages each thereof including only one diode-laser mounted on a heat sink, the sub-packages being mounted on the mounting surface of the base via a thermally conductive but electrically insulating layer, each diode-laser having an emitting aperture from which a beam of laser radiation is emitted;

the packages being arranged in first and second groups thereof with the fast-axes of the diode-lasers parallel to the mounting surface of the heat sink;

first and second pluralities of mirrors mounted on the mounting surface of the base-plate, the first and second pluralities of mirrors being associated with respectively the first and second groups of diode laser packages, the packages and mirrors in each group being arranged such that beams emitted from the diode-lasers and reflected from the mirrors propagate about parallel to each other and parallel to the mounting surface of the base-plate, with the beams in from the first and second groups of diode-laser packages propagating in opposite directions, and with any beam from the first group being adjacent a beam from the second group; and

a second plurality of mirrors arranged to intercept the opposite-direction-propagating beams and reflect the beams such that the beams propagate in the same direction with the fast-axes of the beams aligned in the fast-axis direction.

17. The apparatus of claim 16, wherein there are eight diode-laser packages arranged in two groups of four diode-laser packages.

18. The apparatus of claim 16, wherein each diode-laser package includes a cylindrical lens arranged to collimate the beam emitted by the diode-laser before the beam is reflected from a mirror in the first plurality thereof.