Power and spectral monitoring in wavelength beam combining laser systems

Abstract

In various embodiments, monitoring of one or more secondary diffracted beams formed within a laser resonator provides information based at least in part on which a primary diffracted beam formed within the laser resonator is controlled.

What is claimed is: 
     
         1 .- 28 . (canceled) 
     
     
         29 . A method of operating a wavelength beam combining (WBC) laser system comprising (I) a plurality of beam emitters each configured to emit a beam, (ii) transform optics for converging chief rays of the emitted beams toward a diffraction grating, (iii) a diffraction grating for receiving the beams and producing, via diffraction of the beams incident on the diffraction grating, a primary first-order diffracted beam and a secondary first-order diffracted beam, and (iv) a partially reflective output coupler positioned to receive the primary first-order diffracted beam, transmit a first portion of the primary first-order diffracted beam as a multi-wavelength output beam, and reflect a second portion of the primary first-order diffracted beam back toward the plurality of beam emitters, the method comprising:
 detecting power and/or spectral information from the secondary first-order diffracted beam; and 
 controlling the plurality of beam emitters and/or the primary first-order diffracted beam based at least in part on the information. 
 
     
     
         30 . The method of  claim 29 , wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling power and/or current supplied to one or more of the beam emitters based at least in part on the power and/or spectral information. 
     
     
         31 . The method of  claim 29 , wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling a position and/or a tilt angle of at least one of (i) one or more of the beam emitters, (ii) the transform optics, (iii) the diffraction grating, or (iv) the output coupler based at least in part on the power and/or spectral information. 
     
     
         32 . The method of  claim 29 , wherein (i) the diffraction grating is a transmissive diffraction grating, (ii) the primary first-order diffracted beam is a first-order transmission, and (iii) the secondary first-order diffracted beam is a first-order reflection. 
     
     
         33 . The method of  claim 29 , wherein (i) the diffraction grating is a reflective diffraction grating, (ii) the primary first-order diffracted beam is a first-order reflection, and (iii) the secondary first-order diffracted beam is a first-order transmission. 
     
     
         34 . The method of  claim 29 , wherein the diffraction grating produces, via diffraction of the incident beams, a zeroth-order transmission and/or a zeroth-order reflection, and further comprising detecting power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection. 
     
     
         35 . The method of  claim 34 , further comprising controlling the plurality of beam emitters and/or the primary first-order diffracted beam based at least in part on the power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection. 
     
     
         36 . The method of  claim 35 , wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling power and/or current supplied to one or more of the beam emitters based at least in part on the power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection. 
     
     
         37 . The method of  claim 35 , wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling a position and/or a tilt angle of at least one of (i) one or more of the beam emitters, (ii) the transform optics, (iii) the diffraction grating, or (iv) the output coupler based at least in part on the power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection. 
     
     
         38 . The method of  claim 29 , wherein the diffraction grating is tilted in a WBC plane with respect to the incident beams at a non-Littrow angle, whereby an angle between the incident beams and the diffraction grating in the WBC plane is different from an angle between the secondary first-order diffracted beam and the diffraction grating in the WBC plane. 
     
     
         39 . The method of  claim 29 , wherein the diffraction grating is tilted in a WBC plane with respect to the incident beams at a Littrow angle, whereby an angle between the incident beams and the diffraction grating in the WBC plane is equal to an angle between the secondary first-order diffracted beam and the diffraction grating in the WBC plane. 
     
     
         40 . The method of  claim 39 , wherein the diffraction grating is tilted in a non-WBC plane with respect to the incident beams at a non-Littrow angle, whereby an angle between the incident beams and the diffraction grating in the non-WBC plane is different from an angle between the secondary first-order diffracted beam and the diffraction grating in the non-WBC plane. 
     
     
         41 . A method of operating a laser resonator, the method comprising:
 emitting a plurality of beams from a plurality of beam emitters;   diffracting the plurality of beams to form a primary beam and one or more secondary beams;   propagating a first portion of the primary beam back to the plurality of beam emitters;   outputting a second portion of the primary beam;   detecting power and/or spectral information from at least one said secondary beam; and   controlling the plurality of beam emitters and/or the primary beam based at least in part on the power and/or spectral information from the at least one said secondary beam.   
     
     
         42 . The method of  claim 41 , wherein the primary beam comprises a first-order diffracted transmission, and the one or more secondary beams comprise at least one of (i) a first-order diffracted reflection, (ii) a zeroth-order diffracted transmission, or (iii) a zeroth-order diffracted reflection. 
     
     
         43 . The method of  claim 41 , wherein the primary beam comprises a first-order diffracted reflection, and the one or more secondary beams comprise at least one of (i) a first-order diffracted transmission, (ii) a zeroth-order diffracted transmission, or (iii) a zeroth-order diffracted reflection. 
     
     
         44 . The method of  claim 41 , wherein controlling the plurality of beam emitters and/or the primary beam comprises controlling power and/or current supplied to one or more of the beam emitters based at least in part on the power and/or spectral information from the at least one said secondary beam. 
     
     
         45 . The method of  claim 41 , wherein (i) the plurality of beams are diffracted by a diffraction grating, and (ii) the diffraction grating is tilted in a WBC plane with respect to the incident beams at a non-Littrow angle. 
     
     
         46 . The method of  claim 41 , wherein (i) the plurality of beams are diffracted by a diffraction grating, and (ii) the diffraction grating is tilted in a WBC plane with respect to the incident beams at a Littrow angle. 
     
     
         47 . The method of  claim 46 , wherein the diffraction grating is tilted in a non-WBC plane with respect to the incident beams at a non-Littrow angle. 
     
     
         48 .- 88 . (canceled)