Abstract

We report a novel pump-probe switching phenomenon exhibited by gain-switched vibronic lasers under dual pulse excitation. A spatio-temporal rate equation model reveals the mechanism responsible, and predicts observations of pump-probe switching in a Cr:forsterite laser under pulsed 1064nm excitation. The sensitivity of this energy storage-extraction process to the pump and probe fluences and their temporal separation is investigated for switching in the nanosecond and microsecond excitation regimes.

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  1. J. C. Walling, H. P. Jenssen, R. C. Morris, E. W. O Dell, and O. G. Petersen, "Tunable laser performance in BeAl2O4:Cr 3+ ," Opt. Lett. 4, 182-183 (1979).
    [CrossRef] [PubMed]
  2. P. F. Moulton, "Spectroscopic and laser characteristics of Ti:Al2O3," J. Opt. Soc. Am. B 3, 125-132 (1986).
    [CrossRef]
  3. V. Petricevic, S. K. Gayen, R. R. Alfano, K. Yamagishi, H. Anzai, and Y. Yamaguchi, "Laser action in chromium doped forsterite," Appl. Phys. Lett. 52, 1040-1042 (1988).
    [CrossRef]
  4. N. B. Angert, N. I. Borodin, V. M. Garmash, V. A. Zhitnyuk, A. G. Okhrimchuk, O. G. Siyuchenko, and A. V. Shestakov, "Lasing due to impurity colour centres in yttrium aluminium garnet crystals at wavelengths in the range 1.35-1.45um," Sov. J. Quantum Electron. 18, 73-74 (1988).
    [CrossRef]
  5. P. F. Moulton, "Tunable solid-state lasers," Proceedings of the IEEE 80, 348-364 (1992).
    [CrossRef]
  6. Z. X. Jiang, I. T. M c Kinnie, L. A. W. Gloster, and T. A. King, "Temporal and kinetic studies of chromium forsterite oscillators with 1064nm laser excitation," Pure Appl. Opt. 5, 77-88 (1997).
    [CrossRef]
  7. R. T. White, I. T. M c Kinnie, and N. L. Moise, "Pump-probe switching in Cr:forsterite lasers," in Quantum Electronics and Laser Science Conference, 1997 OSA Technical Digest Series (Optical Society of America, Washington D.C., 1997), 147-148.
  8. W. Jia, H. Liu, S. Jaffe, and W. M. Yen, "Spectroscopy of Cr 3+ and Cr 4+ ions in forsterite," Phys. Rev. B 43, 5234-5242 (1991).
    [CrossRef]
  9. T. S. Rose, R. A. Fields, M. H. Whitmore, and D. J. Singel, "Optical Zeeman spectroscopy of the near-infrared lasing center in chromium:for-sterite," J. Opt. Soc. Am. B 11, 428-435 (1994).
    [CrossRef]
  10. H. R. Verdun, and L. Merkle, "Evidence of excited-state absorption of pump radiation in the Cr:forsterite laser," OSA Proceedings on Advanced Solid-State Lasers, George Dube and Lloyd Chase, eds. (Optical Society of America, Washington D.C., 1991) 10, 35-40.
  11. R. T. White, I. T. Mc Kinnie, and N. L. Moise, "Dynamics of gain-switched Cr 4+ lasers," in preparation.

Other (11)

J. C. Walling, H. P. Jenssen, R. C. Morris, E. W. O Dell, and O. G. Petersen, "Tunable laser performance in BeAl2O4:Cr 3+ ," Opt. Lett. 4, 182-183 (1979).
[CrossRef] [PubMed]

P. F. Moulton, "Spectroscopic and laser characteristics of Ti:Al2O3," J. Opt. Soc. Am. B 3, 125-132 (1986).
[CrossRef]

V. Petricevic, S. K. Gayen, R. R. Alfano, K. Yamagishi, H. Anzai, and Y. Yamaguchi, "Laser action in chromium doped forsterite," Appl. Phys. Lett. 52, 1040-1042 (1988).
[CrossRef]

N. B. Angert, N. I. Borodin, V. M. Garmash, V. A. Zhitnyuk, A. G. Okhrimchuk, O. G. Siyuchenko, and A. V. Shestakov, "Lasing due to impurity colour centres in yttrium aluminium garnet crystals at wavelengths in the range 1.35-1.45um," Sov. J. Quantum Electron. 18, 73-74 (1988).
[CrossRef]

P. F. Moulton, "Tunable solid-state lasers," Proceedings of the IEEE 80, 348-364 (1992).
[CrossRef]

Z. X. Jiang, I. T. M c Kinnie, L. A. W. Gloster, and T. A. King, "Temporal and kinetic studies of chromium forsterite oscillators with 1064nm laser excitation," Pure Appl. Opt. 5, 77-88 (1997).
[CrossRef]

R. T. White, I. T. M c Kinnie, and N. L. Moise, "Pump-probe switching in Cr:forsterite lasers," in Quantum Electronics and Laser Science Conference, 1997 OSA Technical Digest Series (Optical Society of America, Washington D.C., 1997), 147-148.

W. Jia, H. Liu, S. Jaffe, and W. M. Yen, "Spectroscopy of Cr 3+ and Cr 4+ ions in forsterite," Phys. Rev. B 43, 5234-5242 (1991).
[CrossRef]

T. S. Rose, R. A. Fields, M. H. Whitmore, and D. J. Singel, "Optical Zeeman spectroscopy of the near-infrared lasing center in chromium:for-sterite," J. Opt. Soc. Am. B 11, 428-435 (1994).
[CrossRef]

H. R. Verdun, and L. Merkle, "Evidence of excited-state absorption of pump radiation in the Cr:forsterite laser," OSA Proceedings on Advanced Solid-State Lasers, George Dube and Lloyd Chase, eds. (Optical Society of America, Washington D.C., 1991) 10, 35-40.

R. T. White, I. T. Mc Kinnie, and N. L. Moise, "Dynamics of gain-switched Cr 4+ lasers," in preparation.

Supplementary Material (1)

» Media 1: MOV (28 KB)     

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Figures (7)

Fig. 1.
Fig. 1.

Energy level diagram of the Cr4+ ion in forsterite indicating the important transitions. N 2 and τf are the Cr4+ population density and the fluorescence lifetime of the 3T2 state, respectively.

Fig. 2.
Fig. 2.

Computer simulation of gain-switching in a Cr:forsterite laser. Surfaces show the spatio-temporal evolution of (a) the pump rate P, (b) the 3T2 state population density N 2, and (c) the total (left and right travelling) laser intensity I, inside the laser rod.

Fig. 3.
Fig. 3.

Experimental Configuration.

Fig. 4.
Fig. 4.

Observations of dual long pulse (420ns) gain-switching in a Cr:forsterite laser. The strong-weak pump pulse pair (upper trace) can produce either (a) a strong-weak, or (b) a weak-strong Cr:forsterite laser pulse pair (lower trace). The latter is an example of pump-probe switching.

Fig. 5.
Fig. 5.

Computer simulations of dual long (420ns) pulse excitation of a Cr:forsterite laser. The strong-weak pump pulse pair (upper trace) can produce either a (a) strong-weak or (b) weak-strong laser pulse pair (lower trace), depending on the intensity and duration of the two pump pulses.

Fig. 6.
Fig. 6.

(a) Computer simulation of single pulse gain-switching of a Cr:forsterite laser showing the 7mJ, b-axis polarised pump pulse (upper), 3T2 state population (center), and Cr:forsterite laser emission (lower). In the case shown, 43% of the initial 3T2 population remains after the Cr:forsterite laser pulse. (b) Predicted dependence of the residual 3T2 population (normalised to the total number of Cr4+ ions) on pump pulse energy for excitation with 50ns, b-axis polarised pump pulses.

Fig. 7.
Fig. 7.

Animation showing the dependence of PPS on the pump-probe temporal separation. The separation of the 15ns, b-axis polarised pump and 40ns, a-axis polarised probe ranges from 640ns to 2.6μs. [Media 1]

Equations (4)

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1 v g P ( z , t ) t + P ( z , t ) z = σ a ( N t N 2 ( z , t ) ) P ( z , t ) ,
N 2 ( z , t ) t = σ st h ν 1 I ( z , t ) N 2 ( z , t ) + P ( z , t ) ( N t N 2 ( z , t ) ) 1 τ f N 2 ( z , t ) ,
1 v g I + ( z , t ) t + I + ( z , t ) z = σ st I + ( z , t ) N 2 ( z , t ) β I + ( z , t ) + h ν l τ s N 2 ( z , t ) ,
1 v g I ( z , t ) t I ( z , t ) z = σ st I ( z , t ) N 2 ( z , t ) β I ( z , t ) + h ν l τ s N 2 ( z , t ) .

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