Abstract

Using both acoustic-optic (AO) Q-switcher and GaAs saturable absorber, a diode-pumped doubly Q-switched Nd:YVO4/KTP green laser is realized for the first time to our knowledge. This laser can generate a symmetric and shorter pulse when compared with purely AO and passive Q-switching. A rate equation model is introduced to theoretically analyze the results obtained in the experiment, in which the spatial distributions of the intracavity photon density, the pump beam and the population-inversion density are taken into account. The numerical solutions of the rate equations are in good agreement with the experimental results.

© 2005 Optical Society of America

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References

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  1. T. T. Kajava and A. L. Gaeta, “Q switching of a diode-pumped Nd:YAG laser with GaAs,” Opt. Lett. 21, 1244-1246 (1996).
    [CrossRef] [PubMed]
  2. T. T. Kajava and A. L. Gaeta, “ Intra-cavity frequency-doubling of a Nd:YAG laser passively Q-switched with GaAs,” Opt. Commun. 137, 93-97 (1997).
    [CrossRef]
  3. L. Chen, S. Zhao, and H. Zhao, “Passively Q-switching of a laser-diode-pumped inrtracavity-frequencydoubling Nd:NYW/KTP laser with GaAs saturable absorber,” Opt. & Laser Technol. 35, 35-567 (2003).
    [CrossRef]
  4. S. Zhao, X. Zhang, J. Zheng, L. Chen, Z. Cheng, and H. Cheng, “Passively Q-switched self-frequencydoubling Nd3+:GdCa4O(BO3)3 laser with GaAs saturable absorber,” Opt. Eng. 41, 559-560 (2002).
    [CrossRef]
  5. Z. Li, Z. Xiong, N. Moore, G. C. Lim, W. L. Huang, and D. X. Huang, “Pulse width reduction in AO Qswitched diode-pumped Nd: YVO4 laser with GaAs coupler,” Opt. Commun. 237, 411-416 (2004).
    [CrossRef]
  6. G. Li, S. Zhao, H. Zhao, K. Yang, and S. Ding, “Rate equations and solutions of a laser-diode end-pumped passively Q-switched intracavity doubling laser by taking into account intracavity laser spatial distribution,” Opt. Commun. 234, 321-328 (2004).
    [CrossRef]
  7. J. Zheng, S. Zhao, Q. Wang, X. Zhang, and L. Chen, “Influence of thermal effect in gain-media on optimum design of LD-end pumped solid state laser,” Acta Photonica Sinica 30, 724-729 (2001) (in Chinese).
  8. C. Pfistner, R. Weber, H. P. Weber, S. Merazzi, and R. Gruber, “Thermal beam distortions in end-pumped Nd:YAG, Nd:GSGG, and Nd:YLF rods,” IEEE J. Quantum Electron. 30, 1605-1615 (1994).
    [CrossRef]
  9. J. Harrison and R. J. Martinsen, “Thermal modeling for mode-size estimation in microlasers with application to linear arrays in Nd:YAG and Tm,Ho:YLF,” IEEE J. Quantum Electron. 30, 2628-2633 (1994).
    [CrossRef]
  10. F. Song, C. Zhang, X. Ding, J. Xu, G. Zhang, M. Leigh, and N. Peyghambarian, “Determination of thermal focal length and pumping radius in gain medium in laser-diode-pumped Nd:YVO4 lasers,” Appl. Phys. Lett. 81, 2145-2147 (2002).
    [CrossRef]
  11. J. Zheng, S. Zhao, Q. Wang, X. Zhang, and L. Chen, “Influence of thermal effect on KTP type-II phasematching second-harmonic generation,” Opt. Commun. 199, 207-214 (2001).
    [CrossRef]
  12. J. Dong, J. Lu, A. Shirakawa, and K. Ueda, “Optimization of the laser performance in Nd3+:YAG ceramic microship lasers,” Appl. Phys. B 80, 39-43 (2005).
    [CrossRef]
  13. G. Li, S. Zhao, K. Yang, and H. Zhao, “Diode-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber,” Chin. Opt. Lett. 2, 462-465 (2004).
  14. X. Zhang, J. Yang, R. Han, and J. Yao, “Acousto-optic-dye double Q-switched laser: theory and experiments,” Chin. J. Lasers 19, 241-246 (1992) (in Chinese).

Acta Photonica Sinica (1)

J. Zheng, S. Zhao, Q. Wang, X. Zhang, and L. Chen, “Influence of thermal effect in gain-media on optimum design of LD-end pumped solid state laser,” Acta Photonica Sinica 30, 724-729 (2001) (in Chinese).

Appl. Phys. B (1)

J. Dong, J. Lu, A. Shirakawa, and K. Ueda, “Optimization of the laser performance in Nd3+:YAG ceramic microship lasers,” Appl. Phys. B 80, 39-43 (2005).
[CrossRef]

Appl. Phys. Lett. (1)

F. Song, C. Zhang, X. Ding, J. Xu, G. Zhang, M. Leigh, and N. Peyghambarian, “Determination of thermal focal length and pumping radius in gain medium in laser-diode-pumped Nd:YVO4 lasers,” Appl. Phys. Lett. 81, 2145-2147 (2002).
[CrossRef]

Chin. J. Lasers (1)

X. Zhang, J. Yang, R. Han, and J. Yao, “Acousto-optic-dye double Q-switched laser: theory and experiments,” Chin. J. Lasers 19, 241-246 (1992) (in Chinese).

Chin. Opt. Lett. (1)

IEEE J. Quantum Electron. (2)

C. Pfistner, R. Weber, H. P. Weber, S. Merazzi, and R. Gruber, “Thermal beam distortions in end-pumped Nd:YAG, Nd:GSGG, and Nd:YLF rods,” IEEE J. Quantum Electron. 30, 1605-1615 (1994).
[CrossRef]

J. Harrison and R. J. Martinsen, “Thermal modeling for mode-size estimation in microlasers with application to linear arrays in Nd:YAG and Tm,Ho:YLF,” IEEE J. Quantum Electron. 30, 2628-2633 (1994).
[CrossRef]

Opt. & Laser Technol. (1)

L. Chen, S. Zhao, and H. Zhao, “Passively Q-switching of a laser-diode-pumped inrtracavity-frequencydoubling Nd:NYW/KTP laser with GaAs saturable absorber,” Opt. & Laser Technol. 35, 35-567 (2003).
[CrossRef]

Opt. Commun. (4)

Z. Li, Z. Xiong, N. Moore, G. C. Lim, W. L. Huang, and D. X. Huang, “Pulse width reduction in AO Qswitched diode-pumped Nd: YVO4 laser with GaAs coupler,” Opt. Commun. 237, 411-416 (2004).
[CrossRef]

G. Li, S. Zhao, H. Zhao, K. Yang, and S. Ding, “Rate equations and solutions of a laser-diode end-pumped passively Q-switched intracavity doubling laser by taking into account intracavity laser spatial distribution,” Opt. Commun. 234, 321-328 (2004).
[CrossRef]

J. Zheng, S. Zhao, Q. Wang, X. Zhang, and L. Chen, “Influence of thermal effect on KTP type-II phasematching second-harmonic generation,” Opt. Commun. 199, 207-214 (2001).
[CrossRef]

T. T. Kajava and A. L. Gaeta, “ Intra-cavity frequency-doubling of a Nd:YAG laser passively Q-switched with GaAs,” Opt. Commun. 137, 93-97 (1997).
[CrossRef]

Opt. Eng. (1)

S. Zhao, X. Zhang, J. Zheng, L. Chen, Z. Cheng, and H. Cheng, “Passively Q-switched self-frequencydoubling Nd3+:GdCa4O(BO3)3 laser with GaAs saturable absorber,” Opt. Eng. 41, 559-560 (2002).
[CrossRef]

Opt. Lett. (1)

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Figures (6)

Fig. 1.
Fig. 1.

Schematic of the experimental setup.

Fig. 2.
Fig. 2.

Temporal profile of single pulse: (a) pure AO Q-switching; (b) double Q-switching; (c) passive Q-switching. Solid lines, oscilloscope traces; dotted lines, calculated results.

Fig. 3.
Fig. 3.

Pulse width versus pump power.

Fig. 4.
Fig. 4.

Pulse width versus repetition rate.

Fig. 5.
Fig. 5.

Average output power versus pump power.

Fig. 6.
Fig. 6.

Beam size versus pump power.

Tables (2)

Tables Icon

Table 1. The parameters of II-type phase-matching KTP crystal.

Tables Icon

Table 2. The parameters of the theoretical calculation.

Equations (32)

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ϕ ( r , t ) = ϕ ( 0 , t ) exp ( 2 r 2 w l 2 ) ,
ϕ i ( r , t ) = w l 2 w i 2 ϕ ( 0 , t ) exp ( 2 r 2 w i 2 ) , ( i = g , a , s , k )
f T = 2 π K c d n d T + α T n 1 w p 2 ξ P in η ,
w p ( z ) = w p 0 + θ p z z 0 ,
E ( ω , r , z , t ) = E ( ω , r ) cos ( K z ω t ) ,
E i ( ω , r ) = E i o exp ( r 2 ω k 2 ) . ( i = o , e )
d E ( 2 ω , r ) d z = i 2 ω d eff n e 2 ω c E 0 o E 0 e exp ( 2 r 2 ω k 2 ) ,
E ( 2 ω , r ) = i 2 ω d eff l k n e 2 ω c E 0 o E 0 e exp ( 2 r 2 ω k 2 ) ,
I = 1 2 n c ε 0 E 2 ,
P i = π ω k 2 4 n c ε 0 E i 2 , ( i = o , e )
I ( 2 ω , r ) = 32 ω 2 d eff 2 l k 2 c 3 ε 0 n e 2 ω n o ω n e ω P 0 o P 0 e ( π ω k 2 ) 2 exp ( 4 r 2 ω k 2 ) ,
I ( ω , r ) = I o ( ω , r ) + I e ( ω , r )
= 2 π ω k 2 exp ( 2 r 2 ω k 2 ) ( P 0 o + P 0 e ) .
P 0 o = P 0 e = ( 1 2 ) P ( ω , 0 ) ,
δ N = P ( 2 ω , r ) P ( ω , r ) = I ( 2 ω , r ) I ( ω , r )
= K N ω c l k 2 exp ( 2 r 2 ω k 2 ) ϕ k ( 0 , t )
= δ k ϕ k ( r , t ) ,
K N = ω 2 d eff 2 c 3 ε 0 n e 2 ω n 0 ω n e ω ,
δ k = K N ω c l k 2 .
r p ( r , z ) = 2 α π w p 2 ( z ) η exp ( 2 r 2 w p 2 ( z ) ) exp ( α z ) .
0 d ϕ ( r , t ) d t 2 π r d r = 0 1 t r { 2 σ ( 0 l n ( r , z , t ) d z ) ϕ g ( r , t ) 2 σ + n + ( r , t ) l s ϕ s ( r , t )
2 σ 0 n 0 n + ( r , t ) l s ϕ s ( r , t ) B l s ϕ s 2 ( r , t )
δ a ( t ) ϕ a ( r , t ) δ k ϕ k 2 ( r , t ) L ϕ ( r , t ) } 2 π r d r ,
d n ( r , z , t ) d t = W p r p ( r , z ) σ c n ( r , z , t ) ϕ g ( r , t ) n ( r , z , t ) τ ,
d n + ( r , t ) d t = c ϕ s ( r , t ) { σ 0 [ n 0 n + ( r , t ) ] σ + n + ( r , t ) } ,
δ a ( t ) = δ a exp [ ( t t s ) 2 ] ,
n ( r , z , 0 ) = n ( 0 , 0 , 0 ) exp ( 2 r 2 w p 2 ( z ) ) exp ( α z ) ,
n + ( r , 0 ) = n + ,
n ( 0 , 0 , 0 ) = 2 α W p π w p 2 ( 0 ) η f p ,
0 d ϕ ( r , t ) d t 2 π r d r
= 0 1 t r { 2 σ ( 0 l n ( r , z , t ) d z ) ϕ g ( r , t ) δ a ( t ) ϕ a ( r , t ) δ k ϕ k 2 ( r , t ) L ϕ ( r , t ) } 2 π r d r ,
d n ( r , z , t ) d t = W p r p ( r , z ) σ c n ( r , z , t ) ϕ g ( r , t ) n ( r , z , t ) τ .

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