Coherent light generators – Particular temperature control – Heat sink
Reexamination Certificate
1998-10-13
2001-09-25
Davie, James W. (Department: 2881)
Coherent light generators
Particular temperature control
Heat sink
Reexamination Certificate
active
06295307
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to laser diodes, particularly to a laser diode assembly which promotes accurate spacing and alignment of diode bars, cooling of diode bars and electrical conductivity through the diode bars.
2. Background Art
Laser diode arrays are in general use in a wide variety of industrial and research applications. Pluralities of diode bars are mounted upon a substrate to provide the multiplied power of numerous bars, versus the effect offered by a single bar. To optimize the efficiency of a multiple diode bar array, it is desirable not only that the diode bars be properly aligned so that their emitter surfaces face the same direction, but electrical conductivity between bars and cooling of the bars should be optimized.
Most efforts in the art have focused upon modes and means of mounting numerous diode bars quickly and inexpensively. The mounting of numerous bars into a single array historically has been a somewhat labor and/or cost intensive proposition, thus partially impeding the development of economical products and devices incorporating laser diode arrays.
U.S. Pat. Nos. 5,040,187 and 5,284,790, both to Karpinski, show a “monolithic” laser diode array. The disclosure teaches a substrate having a number of grooves therein, and into which the diode bars are inserted. The substrate ostensibly is flexed into an arc to widen the grooves; the diode bars are inserted into the temporarily widened grooves, after which the substrate is relaxed and allowed elastically to return to its normal shape, which results in an effective narrowing of the grooves thereby to help hold the inserted diodes in place. A variety of “submounts” for the array also are taught. However, the methods and configurations of the disclosures are not conducive to diode bar alignment, as the bars tend to tip and roll within the grooves during assembly.
U.S. Pat. No. 5,128,951 to Karpinski also shows a particular type of laser diode array and method of fabrication. The disclosure has to do with providing an inexpensive mode of manufacturing a diode bar array. A substrate is provided with two layers, an upper conductive layer immediately above and in flush contact with a lower non-conductive layer. The grooves for receiving the diode bars are cut into the substrate so as to completely pierce the upper layer and penetrate into the lower non-conductive layer. The disclosure purports thereby to provide a means for mounting diode bars which promotes conductivity between bars while also providing heat transfer into the lower electrically insulating layer. The diode bars do not have optimal contact with the “heat sink” lower layer, and maximized alignment of the bars in the grooves also is not taught.
U.S. Pat. No. 5,305,344 to Patel discloses a laser diode array. The disclosure teaches diversity in diode bar packing, and a configuration which possibly eases the replacement of defective individual bars, but is comparatively complex and expensive.
U.S. Pat. No. 5,311,535 to Karpinski shows a laser diode array which provides for laser emission from the minor surfaces of the diode bars. The device involves the disposition of diode bars into a grooved substrate. Diode bar alignment is not carefully optimized.
Other United States patents of interest in the field include U.S. Pat. No. 5,644,586 to Kawano et al.; U.S. Pat. No. 5,627,850 to Irwin et al.; U.S. Pat. No. 5,568,498 to Nilsson; Pat. No. 5,497,391 to Paoli; U.S. Pat. No. 5,418,799 to Tada; U.S. Pat. No. 5,440,577 to Tucker; U.S. Pat. No. 5,394,426 to Joslin; U.S. Pat. No. 5,212,707 to Heidel et al.; U.S. Pat. No. 5,105,430 to Mundinger et al.; U.S. Pat. No. 5,031,187 to Orenstein et al.; U.S. Pat. No. 5,061,974 to Onodera et al; U.S. Pat. No. 5,060,237 to Peterson; U.S. Pat. No. 4,980,893 to Thornton et al.; U.S. Pat. No. 4,947,401 to Hinata et al.; U.S. Pat. No. 4,903,274 to Taneya et al.; U.S. Pat. No. 4,881,237 to Donnelly; and U.S. Pat. No. 4,092,614 to Sakuma et al. Nevertheless, a need remains for a means and method of providing a laser diode array which at once is simple and economical, and yet optimizes proper diode bar alignment to promote emission efficiency without sacrificing efficient electrical conductivity between, and cooling of, the diode bars. Against this background, the present invention was developed.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
The invention includes a wedged array embodiment of a diode bar assembly, a stacked array embodiment, and methods and apparatus for assembling the stacked and wedged arrays.
According to the invention, there is provided a laser diode assembly comprising a base substrate comprising a major surface having at least one groove therein, the at least one groove defined by a first wall and a second wall, the walls being nonparallel and converging toward a bottom of the at least one groove; a diode bar within the at least one groove; and a conductive wedge in electrical contact with the diode bar and forcibly inserted into the groove between the diode bar and the second wall, thereby to press the diode bar against the first wall. Preferably, a plurality of diode bars are disposed within corresponding ones of a plurality of grooves, each groove defined by a first wall and a second wall, the first wall and the second wall being nonparallel and converging toward a bottom of each groove. The groove's first wall is perpendicular to the major surface of the substrate, while the second wall is inclined in relation to the major surface and intersects the bottom of the groove at an angle. Preferably, each wedge comprises a first face and a second face intersecting at an angle substantially complementary to the angle of the second wall. The grooves are disposed in adjacent rows, and the rows may be parallel rectilinear or parallel curved.
Also, the inventive assembly includes means for providing series electrical contact between a first diode bar in a first groove and a second diode bar in an adjacent second groove in the substrate. The means for providing series electrical contact may comprise a conductive coating upon the first walls of the grooves and a major surface of the substrate and a conductive coating upon the diode bars. Or, the means for providing series contact comprises a first conductive strip extending between the first diode bar and the wedge in the second groove, and a second conductive strip disposed between the wedge and second wall of the second groove, and a third conductive strip between the wedge and the diode bar in the second groove. The three conductive strips can be integrated into a single conductive strip insertable into the adjacent grooves.
In another version of the wedged array embodiment, means are supplied for providing parallel electrical contact between a first diode bar in a first groove and a second diode bar in an adjacent second groove, wherein the base substrate defines a plurality of apertures there through, and the parallel contact means comprising a conductor bar. The conductor bar has a first conductive member insertable through an aperture in the base substrate for electrical contact with the wedge in the first groove, a second conductive member insertable through another aperture in the base substrate for electrical contact with the second diode in the second groove, and a conductive bridge member connecting the two conductive members.
Also in accordance with the invention, there is provided a laser diode assembly comprising a planar, electrically non-conductive, heat spreader substrate having a first face and a second face; at least one electrically conductive layer disposed upon the first face of the substrate; at least two adjacent electrically conductive spacers physically and electrically connected to the conductive layer, each of the conductive spacers in parallel spaced relation from adjacent ones of the spacers to define a gap between each two adjacent the spacers; and at least one laser diode bar disposed in the gap between adjacent the spacers, held by and i
Hoden Brian P.
Jacob Jon B.
Baker Rod D.
Davie James W.
Decade Products, Inc.
Peacock Deborah A.
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