Abstract:
A two-dimensional surface mounted diode laser array package includes a one-piece multifunctional integral array member having a broad area heat sink, laser mounting stages, and interspersed angled deflecting mirrors, all fashioned of a common material. Diode laser bars are secured to the mounting stages between the angled deflecting mirrors. The broad area heat sink, laser mounting stages, and interspersed angled deflecting mirrors, being of the same substance, can be easily fashioned by conventional micro-machining techniques.

Description:
CROSS REFERENCES TO CO-PENDING APPLICATIONS 
     None. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the field of high power semiconductor laser array packages, and more specifically provides a two-dimensional surface mounted diode laser array package configuration for high power laser output, which is efficient in operation. 
     2. Description of the Prior Art 
     Prior art diode laser packages required assembly from several parts made from different materials. In the present invention, the whole lower region of the surface mounted array package, upon which package laser diodes are mounted, is made from the same material and can be readily micro-machined, which facilitates; industrial production of the surface mounted 2-D diode laser array packages. The prior art high power diode laser packaging techniques mounted the diode laser bars on thin heat sink sheets and then stacked them together. These bar-stack packages have shortcomings compared to the surface-mount package, such as the difficulties for replacement of the dead or malfunctioning laser bars, difficulty for automatic manufacturing methods, requirement of high-reflectivity coating for the laser diodes, and ineffective heat removal. 
     The present invention overcomes the problems found in prior art devices and is intended for use in packaging high power semiconductor lasers in order to solve the current problems encountered by most of the current construction techniques. The two-dimensional semiconductor laser array package significantly reduces the distance between the hot spots of the laser diode and the heat sink, so that the heat generated in the laser diodes can be removed more efficiently. Since the mirrors and laser mounting stages can be made from the same material as the broad area heat sink, the whole package can be simply manufactured by conventional automated micro-machining technique. The diode lasers are mounted on the open surface of the package and between the angled mirrors, so they can be accessed easily for automated manufacturing and replacement of damaged lasers. 
     SUMMARY OF THE INVENTION 
     The general purpose of the present invention is to provide a surface-mount construction for packaging high power diode laser bars. 
     According to one embodiment of the present invention, there is provided a surface mounted 2-D diode laser array package comprised of a one-piece integral member including a heat sink and a group of parallel flat mounting stages separated by V-shaped angled mirrors with flat or parabolic reflecting surfaces, and laser diodes suitably attached to the mounting stages. The mounting stages have the same width as the laser diode bars and are slightly higher than the bottoms of the angled mirrors in order to deflect the laser light efficiently. Ceramic standoffs align adjacent to the ends of the laser diodes and the angled mirrors to provide for connection to the laser diodes. High power diode laser bars are surface mounted on the stages to allow for maximum heat removal. Laser light emitted equally from opposing facets of the laser bars is deflected into free space by the angled mirrors and then collected by external optics. 
     One significant aspect and feature of the present invention is a one-piece multifunctional integral array member including laser bar mounting stages, deflection mirrors, and a broad area heat sink, all integrated and made from the same material, for example OFHC copper (Oxygen Free High Conductivity) or silicon, or other suitable thermally conductive material, significantly reducing the fabrication cost of the packages. 
     Another significant aspect and feature of the present invention is that the material could be any material that is thermally conductive and, thus, is not limited to OFHC and Si. 
     Yet another significant aspect and feature of the present invention features diode laser mounting stages which are made from the same material as the heat sink and which are integral with the heat sink, so that the heat generated in the laser can be removed very efficiently by an external heat exchanger. 
     Still another significant aspect and feature of the present invention is the provision of low profile wire-bonding in order to connect the laser diodes to a laser driver without blocking the laser emission. 
     An additional significant aspect and feature of the present invention is that any type of high power diode lasers can be mounted as a member of this invented package. 
     A further significant aspect and feature of the present invention is that the surfaces of the deflection mirrors can be flat, parabolic, or other curved or configured shapes. 
     Having thus described embodiments of the present invention, it is the principal object of the present invention to provide a surface mounted 2-D diode laser array package which provides for the dispersion of heat from and dispersion of laser energy from diode laser bars. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: 
     FIG. 1 illustrates an isometric view of a surface mounted 2-D diode laser array package; 
     FIG. 2 illustrates an exploded view of the major members of FIG. 1; 
     FIG. 3 illustrates a side view of a one piece multifunctional integral array member with laser diodes mounted thereon; 
     FIG. 4 illustrates a cross sectional view of the surface mounted 2-D diode laser array package along lines  4 — 4  of FIG. 1; and, 
     FIG. 5 illustrates the shape and relationship of the laser diodes to the one-piece multifunctional integral array member. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates an isometric view of a surface mounted 2-D diode laser array package  10 , the present invention, and FIG. 2 illustrates an exploded view of the major members of FIG.  1 . With reference to FIGS. 1 and 2, the surface mounted 2-D diode laser array package  10  is now described. The surface mounted 2-D diode laser array package  10  includes a one-piece multifunctional integral array member  12  of OFHC, silicon or other suitable material that is thermally conductive, a plurality of rectangularly shaped laser diodes  14   a - 14   n  in spaced parallel alignment mounted to the one-piece multifunctional integral array member  12 , and ceramic standoffs  16  and  18  aligned to the one-piece multifunctional integral array member  12  at right angles to the opposing ends of the laser diodes  14   a - 14   n . A plurality of gold wire groups, including wire groups  20   a - 20   r  and  22   a - 22   n , or in the alternative gold ribbon groups, are incorporated for connections between the ceramic standoffs are and  18  and the adjacent ends of the laser diodes  14   a - 14   n , as illustrated. Also illustrated as integral parts of the one-piece multifunctional integral array member  12  are a plurality of integral deflecting mirrors  24   a - 24   n  alternately located between a plurality of integral spaced parallel aligned mounting stages  26   a - 26   n . Mounting stages  26   a - 26   n  are also integral parts of the one-piece multifunctional integral array member  12 . The planar region beneath the alternately spaced integral deflecting mirrors  24   a - 24   n  and the mounting stages  26   a - 26   n  forms a broad area integral heat sink  28  to draw heat from the mounted laser diodes  14   a - 14   n , deflecting mirrors  24   a - 24   n , and mounting stages  26   a - 26   n . The integral planar regions adjacent to the integral heat sink  28  form mounting pads  30  and  32  for accommodation and mounting of the ceramic standoffs  16  and  18 , respectively. 
     FIG. 3 illustrates a side view of the one-piece multifunctional integral array member  12  with laser diodes  14   a - 14   n  mounted thereon, where all numerals correspond to those elements previously described. Illustrated in particular is the alignment of the laser diodes  14   a - 14   n  on the mounting stages  26   a - 26   n  in alternate spacing with the deflecting mirrors  24   a - 24   n . Deflecting mirrors  24   a - 24   n  include polished mirror surfaces  50  and  52 . The polished mirror surfaces  50  and  52  are depicted as flat surfaces, but they could be parabolic or other curved shapes. 
     FIG. 4 illustrates a cross sectional view of the surface mounted 2-D diode laser array package  10  along line  4 — 4  of FIG. 1, where all numerals correspond to those elements previously described. Illustrated in particular are the layers of material comprising the heat sink  28 , the laser diode  14   a , and the ceramic standoff  16 . The laser diodes  14   a - 14   n , such as the illustrated diode  14   a , include conductive top and bottom layers of gold foil  34  and  36 , or other suitable conductive material. A layer of solder  38  or other suitable bonding medium, such as indium, secures and bonds the lower gold film layer  36  of the laser diode  14   a  to the upper surface  40  of the mounting stage  26   a . The ceramic standoff  16  includes conductive top and bottom layers of gold film  42  and  44  or other suitable conductive material. A layer of solder  46  or other suitable bonding medium, such as indium, secures and bonds the lower gold film layer  44  of the ceramic standoff  16  to the upper surface  48  of the mounting pad  30 . Wire group  20   a  is suitably welded between the gold film conductor  34  of the laser diode  14   a  and the gold film conductor  42  of the ceramic standoff  16  to provide for transfer of electrical energy from the ceramic standoff  16  to the laser diode  14   a . The location of the wire groups  20   a - 20   n  and  22   a - 22   n  in low profile between the ceramic standoffs  16  and  18  and the adjacent ends of the laser diodes  14   a - 14   n , as viewed in previous FIGS. and in FIG. 5, provides for laser transmission which is not interfered with by the wire group members  20   a - 20   n  and  22   a - 22   n.    
     FIG. 5 illustrates the shape and relationship of the laser diodes  14   a  and  14   b  to the one-piece multifunctional integral array member  12 , where all numerals correspond to those elements previously described. Deflecting mirror  24   b , being similar in construction to the accompanying deflecting mirrors  24   a  and  24   c - 24   n , and located between laser diodes  14   a  and  14   b , includes highly polished mirror surfaces  50  and  52  each opposingly aligned at an angle of 45° Cwith respect to the heat sink  28  and at  900  to each other. Laser beam  53 , emitted from the laser diodes  14   a  and  14   b , and shown as arrows, is reflected in a normal direction by the highly polished mirror surfaces  50  and  52 . The laser radiation emitted from both ends of the laser diodes  14   a  and  14   b  is deflected by the mirrors  24   a - 24   n  toward external collecting optics, so as to provide more operating efficiency. The upper surfaces  40  of the mounting stages, such as mounting stages  26   a  and  26   b , are mounted in a position slightly higher than the bottom portions of the adjacent polished mirror surfaces  50  and  52  to prevent blocking the highly divergent light emitted from the laser diodes  14   a  and  14   b  and to allow a greater field of polished mirror exposure to be utilized. As previously described, it can be seen that the wire groups, such as wire groups  20   a  and  20   b , are located in a position which does not interfere with the reflected laser energy  53 . The surface mounted 2-D diode laser array package  10  can be mounted on a water cooled or an air cooled heat exchanger  54  for effective heat removal. Heat  56  is transferred, as illustrated, from the laser diodes  14   a  and  14   b , and from mounting stages such as mounting stages  26   a  and  26   b , through the broad base heat sink  28  and to the heat exchanger  54  to effect cooling of the surface mounted 2-D diode laser array package  10 . Preferably the thickness of the broad base heat sink  28  is as thin as to facilitate heat dissipation from the laser diodes  4   a - 14   n  and other members. 
     Various modifications can be made to the present invention without departing from the apparent scope hereof. 
     SURFACE MOUNTED 2-D DIODE LASER ARRAY PACKAGE 
     Parts List 
       10  surface mounted 2-Diode laser array package 
       12  one-piece multifunctional integral array member 
       14   a-n  laser diodes 
       16  ceramic standoff 
       18  ceramic standoff 
       20   a-n  wire groups 
       22   a-n  wire groups 
       24   a-n  deflecting mirrors 
       26   a-n  mounting stages 
       28  heat sink 
       30  mounting pad 
       32  mounting pad 
       34  gold film layer or conductor 
       36  gold film layer or conductor 
       38  solder 
       40  upper surface 
       42  gold film layer or conductor 
       44  gold film layer of conductor 
       46  solder 
       48  upper surface 
       50  mirror surface 
       52  mirror surface 
       53  laser beam 
       54  heat exchanger 
       56  heat