Patent ID: 11916349
Assignee: SHANXI UNIVERSITY
Field: Optics (Instruments)
Classification: CPC H  G | IPC G  H

Claim 6:
7. The method for measuring a thermal load caused by ETU in a laser gain crystal according to claim 3, wherein the obtaining thermal focal lengths on the tangential plane and the sagittal plane of the laser gain crystal inside the single-frequency laser by substituting the average pump power threshold and the cavity parameters into thermal lens focal length formulas for the tangential plane and the sagittal plane specifically comprises:
obtaining the thermal focal length ft(thermal) on the tangential plane of the laser gain crystal according to the thermal lens focal length formula for the tangential plane, f
      
        t
        ⁡
        
          (
          thermal
          )
        
      
    
    =
    
      
        π
        ⁢
        
          
        
        ⁢
        
          K
          
            
            c
          
        
        ⁢
        
          ω
          p
          2
        
      
      
        ξ
        ⁢
        
          
        
        ⁢
        
          P
          P
        
        ⁢
        
          
            
              d
              ⁢
              n
            
            
              d
              ⁢
              T
            
          
          ⁡
          
            [
            
              1
              -
              
                exp
                ⁡
                
                  (
                  
                    
                      -
                      α
                    
                    ⁢
                    l
                  
                  )
                
              
            
            ]
          
        
      
    
  
  ;

 and
obtaining the thermal focal length on the sagittal plane of the laser gain crystal according to the thermal lens focal length formula for the sagittal plane, f
      
        s
        ⁡
        
          (
          thermal
          )
        
      
    
    =
    
      
        π
        ⁢
        
          
        
        ⁢
        
          K
          
            ⊥
            c
          
        
        ⁢
        
          ω
          p
          2
        
      
      
        ξ
        ⁢
        
          
            
              P
              P
            
            ⁡
            
              (
              
                
                  
                    d
                    ⁢
                    n
                  
                  
                    d
                    ⁢
                    T
                  
                
                +
                
                  
                    0
                    .
                    8
                  
                  ⁢
                  5
                  ×
                  1
                  ⁢
                  
                    0
                    
                      -
                      6
                    
                  
                
              
              )
            
          
          ⁡
          
            [
            
              1
              -
              
                exp
                ⁡
                
                  (
                  
                    
                      -
                      α
                    
                    ⁢
                    l
                  
                  )
                
              
            
            ]
          
        
      
    
  
  ,

 wherein
K| c and K⊥ c represent the thermal conductivity coefficients, which were parallel and perpendicular to the optical axis, respectively, ωP represents the spot size of the pump laser at the laser crystal, represents the thermal load, PP represents the pump threshold of the laser system,, d
    ⁢
    n
  
  
    d
    ⁢
    T
  

 represents the thermo-optic coefficient of the laser crystal, α represents the pump laser absorption coefficient of the laser crystal, l represents the effective length of a doped part of the laser gain crystal ft(thermal) represents the thermal focal length on the tangential plane of the laser gain crystal, and fs(thermal) represents the thermal focal length on the sagittal plane of the laser gain crystal.