Micro-heatpipe cooled laser diode array

• US 5,309,457 A
• Filed: 12/22/1992
• Issued: 05/03/1994
• Est. Priority Date: 12/22/1992
• Status: Expired due to Fees

• Current Assignee: Richard B. Minch
• Original Assignee: Richard B. Minch
• Inventors: Minch, Richard B.
• Primary Examiner(s): Gonzalez, Frank
• Application Number:
  US07/994,651
• Time in Patent Office: 497 Days
• Field of Search: 372/18, 372/34, 372/35, 372/69, 372/75
• US Class Current: 372/34
• CPC Class Codes: F28D 15/0233 the conduits having a particular shape, e.g. non-circular cross-section, annular F28D15/0241, F28D15/0266 take precedence
• CPC Class Codes: F28D 15/04 with tubes having a capillary structure
• CPC Class Codes: F28D 2015/0225 Microheat pipes
• CPC Class Codes: H01S 5/02345 Wire-bonding
• CPC Class Codes: H01S 5/024 Arrangements for thermal management
• CPC Class Codes: H01S 5/02423 Liquid cooling, e.g. a liquid cools a mount of the laser
• CPC Class Codes: H01S 5/02469 Passive cooling, e.g. where heat is removed by the housing as a whole or by a heat pipe without any active cooling element like a TEC
• 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

Abstract

A diode laser array made from a plurality of linear laser diode array assemblies affixed and in good thermal communication with bodies containing micro-heatpipes. Assemblies are stacked in a vertical manner to form two dimensional arrays. Each assembly is connected electrically and mechanically to adjacent assemblies to form the final assembly. In one embodiment the bodies are arranged in a vertical stairstep manner such that radiation from an upper assembly stimulates emission in adjacent lower assemblies thereby achieving frequency locking. In another embodiment said micro-heatpipe containing second bodies are fabricated from materials with a coefficient of thermal expansion closely matching with a coefficient of thermal expansion closely matching that of the laser diode array subassemblies. In another embodiment the assemblies form the evaporator of a second heatpipe device cooling means.

Claims

1. A micro-heatpipe cooled laser diode array assembly comprising:

(a) a plurality of bodies each containing micro-heatpipe means for heat transfer;

(b) an assembly comprising a single laser diode array bar affixed with means providing good thermal contact to principal surfaces of said bodies;

(c) multiple said assemblies held with a mechanical means for holding said assemblies in a stair-step stacking manner and with electrical means for providing electrical energy to said assemblies, whereby a portion or all of the end of said micro-heatpipe bodies are hidden behind the said laser diode array bars thereby increasing the percentage of the surface normal to the radiation direction emitting radiation.

2. The assembly of claim 1 wherein cooling means are provided for the ends of said bodies not attached to said laser diode array bars, wherein the heat transported away from the said laser diode array bars via said micro-heatpipe bodies is subsequently removed from the said micro-heat pipe bodies.

3. The assembly of claim 1 wherein mounting means of said multiple assemblies are provided by passing said assemblies through wall of a sealed enclosure containing a dielectric fluid and capillary means for returning said fluid from all parts of said enclosure to said multiple assemblies;

whereby said fluid is evaporated at multiple said assemblies with resulting vapor phase of said fluid passing to other parts of said enclosure and condensing with released heat being passed through said enclosure walls to the exterior and the condensed liquid phase of said fluid being returned to said assemblies by capillary action for re-evaporation.

4. The assembly of claim 1 wherein mounting means of multiple assemblies are provided by passing said assemblies through wall of an enclosure with an entrance and an exit with means for passing a dielectric fluid over said multiple assemblies, wherein said assembly is cooled by convection.

5. The assembly of claim 1 wherein the said bodies are fabricated from a material with a coefficient of thermal expansion which selected to closely match the coefficient of thermal expansion of the said linear diode array bars mounted thereon.

6. A micro-heatpipe cooled laser diode array assembly comprising:

(a) a plurality of bodies each said body comprising a single or a plurality of micro-heatpipe(s) each said micro-heatpipe having an elongated closed chamber extending within said body from said first end to said second end within which said chamber is contained a specified amount of a fluid which circulates as vapor in a central vapor space portion of the cross-section of said chamber with said fluid evaporation from said first end and passing to said second end as vapor condensing at said second end and returning to said first end in its liquid phase via one or a plurality of artery chambers each of which is in fluidic communication with said vapor space portion of the cross-section of said chamber thereby forming a closed system for the transfer of the heat of evaporation of said fluid from the said first end to the said second end, micro-heatpipe cooled laser diode array further comprising;

(b) one or a plurality of laser diode bars being affixed with means providing good thermal contact to the principal surfaces of said bodies at said first end and oriented such that said micro-heatpipe(s) pass in close proximity to said laser diode bars and parallel the their principal plane;

(c) multiple said assemblies being held with a mechanical mounting means in a stacking manner such that said bodies each containing one or multiple said micro-heal pipes pass between adjacent said assemblies, whereby two-phase heat transfer is effected from the volume located between adjacent said laser diode bars;

(d) each said assembly provided with electrical means for providing electrical energy to said laser diode bars.

7. The assembly of claim 6 additionally comprising a convective or boiling cooling means for removing heat from the said second end of the plurality of micro-heatpipes, wherein said second end extends into an enclosure, said enclosure having a first and second opening through which a coolant flows.

8. A micro-heatpipe cooled laser diode array assembly wherein said micro-he atpipes pass between said laser diodes for cooling, said assembly comprising:

(a) plurality of bodies each containing single or multiple micro-heatpipe means for heat transfer;

(b) assemblies each of which comprises one or more linear laser diode array bars affixed with means providing good thermal contact to the principal surfaces of said bodies;

(c) multiple said assemblies held with a mechanical mounting means in a stacking manner by passing said assemblies through the wall of a sealed enclosure containing a specified amount of fluid and a capillary means for returning said fluid from all parts of said enclosure to said multiple assemblies;

whereby said fluid is evaporated at multiple said assemblies with resulting vapor phase of said fluid passing to other parts of said enclosure and condensing with released heat being passed through said enclosure walls to the exterior and the condensed liquid phase of said fluid being returned to said assemblies by capillary action for re-evaporation.

(d) multiple said assemblies provided with electrical means for providing electrical energy to said assemblies.

9. A micro-heatpipe cooled laser diode array assembly wherein said micro-heatpipes pass between said laser diodes for cooling, said assembly comprising:

(a) plurality of bodies each containing single or multiple micro-heatpipe means for heat transfer;

(b) assemblies each of which comprises one or more linear laser diode array bars affixed with means providing good thermal contact to the principal surfaces of said bodies;

(c) mechanical mounting means of said multiple assemblies are provided by passing said assemblies through the wall of an enclosure with an entrance and an exit with means for passing a dielectric fluid through said enclosure and over said multiple assemblies, wherein said assemblies are cooled by convection or boiling;

(d) multiple said assemblies provided with electrical means for providing electrical energy to said assemblies.

10. The assembly of claim 9 wherein the said bodies are fabricated from a material with a coefficient of thermal expansion which is selected to closely match the coefficient of thermal expansion of the said linear laser diode bars mounted thereon.

11. A micro-heatpipe cooled laser diode array comprising:

(a) a plurality of assemblies each said assembly comprising a body with a first end and a second end with each said assembly further comprising single or multiple laser diode bars attached to said first end of said body with a mechanical means having good thermal conductivity;

(b) each said body further comprising a single or a plurality of micro-heatpipe(s) each said micro-heatpipe having an elongated closed chamber extending within said body from said first end to said second end within which said chamber is contained a specified amount of a fluid which circulates as vapor in a central vapor space portion of the cross-section of said chamber with said fluid evaporation from said first end and passing to said second end as vapor condensing at said second end and returning to said first end in its liquid phase via one or a plurality of artery chambers each of which is in fluidic communication with said vapor space portion of the cross-section of said chamber thereby forming a closed system for the transfer of the heat of evaporation of said fluid from the said first end to the said second end;

(c) multiple said assemblies being held in a two dimensional close packed arrangement with the principal axis of each said assembly parallel with the principal axis of every other said assembly and with all said first ends grouped together and all said second ends grouped together;

(d) each said assembly being provided with electrical means for providing electrical energy to said assemblies.

12. The micro-heatpipe cooled laser diode array of claim 11 additionally comprising a cooling means for removing hat from the said second end of the said plurality of assemblies.

13. The micro-heatpipe cooled laser diode array of claim 11 wherein mechanical mounting means of said multiple assemblies are provided by passing said assemblies through the wall of a sealed enclosure containing a dielectric fluid and capillary means for returning said fluid from all parts of said enclosure to said multiple assemblies whereby said fluid is evaporated at said multiple assemblies with resulting vapor phase of said fluid passing to other parts of said enclosure and condensing with release heat of condensation of said fluid being passes through said enclosure walls to the exterior and condensed liquid phase of said fluid being returned to said multiple assemblies by said capillary means for re-evaporation.

14. The micro-heatpipe cooled laser diode array of claim 11, wherein mechanical mounting means of multiple assemblies are provided by passing said assemblies through the wall of an enclosure with said enclosure further comprising an entrance opening and an exit opening with means for passing a dielectric fluid into said enclosure through said entrance opening said dielectric fluid passing over said second ends of said assemblies and exiting enclosure through said exit opening, whereby said multiple assemblies are cooled by convection or boiling.

15. The micro-heatpipe cooled laser diode array of claim 11 wherein a portion of the radiation from the upper said assemblies stimulates radiative emission from one or more said assemblies located in a lower vertical relationship, whereby frequency locking of the micro-heatpipe cooled laser diode array is obtained.

16. The micro-heatpipe cooled laser diode array of claim 11 wherein the said bodies are fabricated from a material with a coefficient of thermal expansion which is selected to closely match the coefficient of thermal expansion of the said laser diode array bars mounted thereon.