High efficiency, high power direct diode laser systems and methods therefor

Abstract

A direct diode laser system includes N laser head assemblies (LHAs) generating N output beams, N optical fibers receiving respective N output beams and generating N received output beams, and a torch head recollimating and focusing the N received output beams onto a single spot. Preferably, each of the laser head assemblies of the direct diode laser system includes M modules generating M laser beams, wherein each of the M laser beams has a corresponding single wavelength of light. M- 1 dichroic filters, wherein each of the M- 1 dichroic filter transmits a corresponding one of the M laser beams and reflects all other wavelengths, and a fiber coupling device collecting the M laser beams to produce a respective one of the N output beams. In an exemplary case, the M- 1 dichroic filters function as band pass filters. A method of generating a high fluence, high power laser beam is also described.

1. A diode laser system, comprising:
 N laser head assemblies (LHAs) generating N output beams, wherein each of said N LHAs includes:  
 M modules generating M laser beams, wherein each of said M laser beams has a different single wavelength;  
 M-2 dichroic filters, wherein each of said M-2 dichroic filters transmits a corresponding one of said M laser beams and reflects all other of said M laser beams;  
 a fiber coupling device collecting said M laser beams to produce a respective one of said N output beams;  
 N optical fibers receiving respective ones of said N output beams and generating N received output beams; and  
 an optical assembly recollimating and focusing said N received output beams on a single spot,  
 where N and M are both integers ≧2.  
 
     
     
       2. The diode laser system as set forth in  claim 1 , further comprising N LHA controllers controlling the output power produced by respective ones of said N LHAs. 
     
     
       3. The diode laser system as set forth in  claim 1 , further comprising a LHA controller controlling the output power produced by all of said N LHAs. 
     
     
       4. The diode laser system, as set forth in  claim 1 , wherein said optical assembly comprises:
 N collimating lenses for recollimating respective ones of said N output beams; and  
 a single transform lens focusing said recollimated N output beams onto said single spot.  
 
     
     
       5. The diode laser system as set forth in  claim 4 , wherein said single spot corresponds to one end of a solid state laser rod. 
     
     
       6. The diode laser system as set forth in  claim 4 , wherein said single spot corresponds to one end of a rare earth doped optical fiber. 
     
     
       7. The diode laser system as set forth in  claim 1 , wherein each of said LHAs comprises:
 M/2 first modules generating M/2 first laser beams, wherein each of said M/2 first laser beams has a corresponding single wavelength;  
 (M/2)-1 dichroic first filters, wherein each of said (M/2)-1 dichroic first filters transmits a corresponding one of said M/2 first laser beams and reflects all other of said M/2 first laser beams;  
 M/2 second modules generating M/2 second laser beams, wherein each of said M/2 second laser beams has a corresponding single wavelength;  
 (M/2)-1 dichroic second filters, wherein each of said (M/2)-1 dichroic second filters transmits a corresponding one of said M/2 second laser beams and reflects all other of said M/2 second laser beams;  
 a polarizer coupling first and second M/2 laser beams to thereby produce M polarization coupled laser beams; and  
 a fiber coupling device collecting said M polarization coupled laser beams to produce a respective one of said N output beams.  
 
     
     
       8. The diode laser system as set forth in  claim 1 , wherein said each of said M-2 dichroic filters band pass filters said corresponding one of said M laser beams and reflects all other of said M laser beams. 
     
     
       9. A diode laser system, comprising:
 N laser head assemblies (LHAs) generating N output beams, wherein each of said N LHAs includes:  
 M first modules generating M first laser beams, wherein each of said M first laser beams has a different single wavelength;  
 M-1 first dichroic filters defining a first optical waveguide for directing all of said M first laser beams into a first optical path, wherein each of said M-1 first dichroic filters transmits a corresponding one of said M first laser beams and reflects all other said M first laser beams;  
 a fiber coupling device disposed adjacent to said first optical path collecting said M first laser beams to produce a respective one of said N output beams;  
 N optical fibers receiving respective ones of said N output beams and generating N received output beams; and  
 an optical assembly recollimating and focusing the N received output beams onto a single spot,  
 where N and M are both integers ≧2.  
 
     
     
       10. The diode laser system as set forth in  claim 9 , wherein said optical assembly comprises:
 N collimating lenses for recollimating said N output beams; and  
 a single transform lens for focusing said recollimated N output beams onto said single spot.  
 
     
     
       11. The diode laser system as set forth in  claim 10 , wherein said single spot corresponds to one end of a laser amplifying medium. 
     
     
       12. The diode laser system as set forth in  claim 9 , wherein each of said LHAs further comprises:
 M second modules generating M second laser beams, wherein each of said M second laser beams has a different single wavelength;  
 M-1 second dichroic filters defining a second optical waveguide for directing all of said M second laser beams into a second optical path, wherein each of said M-1 second dichroic filters transmits a corresponding one of said M second laser beams and reflects all other said M second laser beams;  
 a rotating element for rotating the polarizations of said M second laser beams; and  
 a polarizer disposed at the intersection of said first and second optical paths coupling said M first and M second laser beams into the second optical path to thereby produce 2M polarization coupled laser beams;  
 wherein said fiber coupling device collects said 2M polarization coupled laser beams to produce a respective one of said N output beams.  
 
     
     
       13. The diode laser system as set forth in  claim 9 , wherein said fiber coupling device comprises a transform lens receiving and coupling said M first laser beams to one of said N optical fibers to thereby produce a respective one of said N output beams. 
     
     
       14. A diode laser system, comprising:
 means for generating N laser beams, wherein each of said N laser beams includes multiple wavelengths of light and wherein said generating means comprises:  
 M first means for generating M first laser beams, wherein each of said M first laser beams has a different single wavelength;  
 M-1 first filter means defining a first optical waveguide for directing all of said M first laser beams into a first optical path, wherein each of said M-1 first filter means transmits a corresponding one of said M first laser beams and reflects all other said M first laser beams;  
 fiber coupling means disposed adjacent to said first optical path for collecting said M first laser beams and for producing a respective one of said N output laser beams;  
 N optical fiber means receiving respective one of said N output laser beams for generating N received output beams; and  
 output means for recollimating and for focusing said N received output beams on a single spot,  
 where N and M are both integers ≧2.  
 
     
     
       15. The diode laser system as set forth in  claim 14 , wherein said output means comprises:
 N collimating lenses for recollimating said N×M laser beams; and  
 a single transform lens focusing said recollimated N×M laser beams onto said single spot.  
 
     
     
       16. The diode laser system as set forth in  claim 14 , wherein said single spot corresponds to one end of a solid state laser. 
     
     
       17. The diode laser system as set forth in  claim 14 , wherein said single spot corresponds to one end of a rare-earth doped optical fiber. 
     
     
       18. The diode laser system as set forth in  claim 14 , wherein said single spot corresponds to one end of a dye laser. 
     
     
       19. The diode laser system as set forth in  claim 14 , wherein said generating means further comprises:
 second means for generating M second laser beams, wherein each of said M second laser beams has a different single wavelength;  
 M-1 second filter means defining a second optical waveguide for directing all of said M second laser beams into a second optical path, wherein each of said M-1 second filter means transmits a corresponding one of said M second laser beams and reflects all other said M second laser beams;  
 rotating means for rotating the polarizations of said M second laser beams; and  
 polarization means disposed at the intersection of said first and second optical paths for coupling said M first and M second laser beams into said second optical path to thereby produce 2M polarization coupled laser beams,  
 wherein said fiber coupling means collects said 2M polarization coupled laser beams to produce a respective one of said N laser beams.  
 
     
     
       20. The diode laser system as set forth in  claim 19 , wherein said first coupling device comprises a transform lens for receiving and for coupling said 2M polarization coupled laser beams to one of said N optical fiber means to thereby produce a respective one of said N output beams. 
     
     
       21. A method for generating a high energy laser beam, comprising:
 (a) generating P collimated laser beams having an Mth wavelength;  
 (b) repeating step (a) M times so as to produce M×P collimated laser beams having M different wavelengths;  
 (c) coupling said M×P collimated laser beams into an optical path;  
 (d) coupling said M×P collimated laser beams into an ith optical fiber to thereby produce a corresponding ith output laser beam, where i=1 to N;  
 (e) repeating steps (a) through (d) N times to thereby generate N output laser beams;  
 (f) recollimating said N output laser beams to produce N recollimated laser beams; and  
 (g) focusing said N recollimated laser beams onto a single spot,  
 where M, N and P are integers ≧2.  
 
     
     
       22. The method as set forth in  claim 21 , wherein step (c) comprises dichroically coupling said M×P collimated laser beams into said optical path. 
     
     
       23. The method as set forth in  claim 21 , wherein step (c) comprises dichroically and polarization coupling said M×P collimated laser beams into said optical path. 
     
     
       24. The method as set forth in  claim 21 , wherein step (c) comprises polarization coupling said M×P collimated laser beams into said optical path. 
     
     
       25. A diode laser system, comprising:
   a laser head assembly generating an output beam, the laser head assembly including:        M modules which generate M laser beams, wherein each of said M laser beams has a different wavelength; and        only M -   2  dichroic filters, wherein each of said M -   2  dichroic filters transmits a corresponding one of said M laser beams and reflects all other of said M laser beams into a predetermined optical path to produce said output beam,        where M is an integer > 2 .     
     
     
       26. A diode laser system, comprising:
   a laser head assembly which generates an output beam, the laser head assembly including:        M modules which generate M laser beams, wherein each of said M laser beams occupies a different wavelength band;        M - R dichroic filters, wherein each of said M - R dichroic filters transmits at least a respective one of said M laser beams occupying a given wavelength band and reflects all other of said M laser beams not occupying the given wavelength band; and        an optical device which combines said M laser beams to thereby produce said output beam,        wherein:        M and R are positive integers;        M - R is greater than or equal to  2 ; and        M and R are integers ≧ 2 .     
     
     
       27. The diode laser system as recited in  claim 26 , wherein the optical device comprises means for collecting said M laser beams to thereby produce said output beam. 
     
     
       28. The diode laser system as recited in  claim 26 , wherein the optical device comprises a fiber coupling device which collects said M laser beams to thereby produce said output beam. 
     
     
       29. The diode laser system as recited in  claim 26 , wherein the optical device comprises a polarization combiner which combines first selected ones of said M laser beams with second selected ones of said M laser beams to thereby produce said output beam. 
     
     
       30. The diode laser system as recited in  claim 29 , wherein the first selected ones of said M laser beams are equal in number to the second selected ones of said M laser beams. 
     
     
       31. A laser head assembly which generates an output beam including M laser beams, comprising:
   M modules generating M laser beams, wherein each of said M laser beams has a different single wavelength; and        no more than M -   2  dichroic filters, wherein each of said M -   2  dichroic filters transmits a corresponding one of said M laser beams and reflects all other of said M laser beams;        wherein M is an integer > 2 .     
     
     
       32. The laser head assembly as recited in  claim 31 , further comprising a fiber coupling device collecting said M laser beams to produce an output beam. 
     
     
       33. A method for generating a high energy laser beam, comprising:
 ( a )  generating P collimated laser beams, each of the P collimated laser beams having an wavelength within a Mth wavelength band;      ( b )  repeating step  ( a )  M times so as to produce M×P collimated laser beams grouped into M different wavelength bands; and      ( c )  coupling said M×P collimated laser beams into an optical fiber to produce a high energy beam,        wherein M and P are integers ≧ 2 .     
     
     
       34. The method as recited in  claim 33 , wherein the step ( c )  comprises dichroically coupling said M×P collimated laser beams into said optical fiber.   
     
     
       35. The method as recited in  claim 33 , wherein the step ( c )  comprises dichroically and polarization coupling said M×P collimated laser beams into said optical fiber.   
     
     
       36. A diode laser system, comprising:
   laser head assembly  ( LHA )  which generates an output beam, the LHA including:        M first modules generating M first laser beams, wherein each of said M first laser beams has a different single wavelength;        M -   1  first dichroic filters defining a first optical waveguide for directing all of said M first laser beams into a first optical path, wherein each of said M -   1  first dichroic filters transmits a corresponding one of said M first laser beams and reflects all other said M first laser beams;        M second modules generating M second laser beams, wherein each of said M second laser beams has a different single wavelength;        M -   1  second dichroic filters defining a second optical waveguide for directing all of said M second laser beams into a second optical path, wherein each of said M -   1  second dichroic filters transmits a corresponding one of said M second laser beams and reflects all other said M second laser beams;        a polarization combiner disposed at the intersection of said first and second optical paths which couples said M first and M second laser beams into the second optical path to thereby produce  2 M polarization coupled laser beams; and        a fiber coupling device disposed adjacent to said first and second optical paths for coupling said  2 M polarization coupled laser beams to thereby produce the output beam,        wherein M is an integer ≧ 2 .     
     
     
       37. A laser head assembly ( LHA )  which generates an output beam, comprising:      M modules generating M laser beams, wherein each of said M laser beams has a different single wavelength;        M - R dichroic filters defining a first optical waveguide for directing all of said M laser beams into a first optical path, wherein each of said M - R dichroic filters transmits at least one of said M laser beams;        S second modules generating S laser beams, wherein each of said S laser beams has a different single wavelength;        S - T dichroic filters defining a second optical waveguide for directing all of said S laser beams into a second optical path, wherein each of said S - T dichroic filters transmits at least one of said S laser beams;        a polarization combiner disposed at the intersection of said first and second optical paths which couple said M and said S laser beams into a common optical path to thereby produce M+S polarization coupled laser beams; and        a fiber coupling device disposed adjacent to said first and second optical paths for coupling said M+S polarization coupled laser beams to thereby produce the output beam,        wherein:        M, R, S and T are positive integers; and        at least one of M and S is ≧ 2 .     
     
     
       38. A diode laser system, comprising:
   means for generating M laser beams, each of said M laser beams having a different wavelength;        M - R filter means defining a first optical waveguide for directing all of said M first laser beams into an optical path, wherein each of said M - R filter means transmits at least one of said M first laser beams; and        fiber coupling means disposed adjacent to said optical path for collecting said M laser beams to thereby produce an output laser beam,        wherein M and R are both positive integers;        wherein M - R is greater than or equal to  2 ; and        wherein M and R ≧ 2 .     
     
     
       39. A diode laser system, comprising:
   first means for generating M first laser beams, wherein each of said M first laser beams has a different single wavelength;        M -   1  first filter means defining a first optical waveguide for directing all of said M first laser beams into a first optical path, wherein each of said M -   1  filter means transmits a corresponding one of said M first laser beams and reflects all other said M first laser beams;        second means for generating M second laser beams, wherein each of said M second laser beams has a different single wavelength;        M -   1  second filter means defining a second optical waveguide for directing all of said M second laser beams into a second optical path, wherein each of said M -   1  second filter means transmits a corresponding one of said M second laser beams and reflects all other said M second laser beams;        polarization combining means disposed at the intersection of said first and second optical paths for coupling said M first and said M second laser beams into said second optical path to thereby produce  2 M polarization coupled laser beams; and        fiber coupling means disposed adjacent to said second optical path for collecting said  2 M polarization coupled laser beams to thereby produce an output laser beam,        wherein M is a integer ≧ 2 .