Demidovich, A. A.

Lisinetskii, V. A.

Loiko, Yu. V.

Voitovich, A. P.

English

Электронная библиотека БГУ

ANALYTICAL SOLUTION FOR PULSE EVOLUTION IN Q-SWITCHED 
LASERS WITH INTRACAVITY RAMAN CONVERSION 
Yu. V. Loiko, A. A. Demidovich, V. A. Lisinetskii, A. P. Voitovich 
Institute of Molecular and Atomic Physics, NASB, Minsk 
Q-switched operation of lasers with intracavity Raman conversion has 
been considered analytically on the basis of the rate equation model. We con-
sider the stationary intracavity stimulated Raman scattering (SRS). The ana-
lytical expressions which describe the shapes of pulses at fundamental laser 
(FL) and Stokes-shifted frequencies have been derived. These expressions de-
scribe the dependence of the FL and Stokes photon number densities on the 
population inversion but they can be transformed to obtain the time evolution 
of the pulses. It has been found that the analytical expressions for the Q-
swicthed lasers with intracavity SRS can be obtained if the similar expres-
sions are known for the identical lasers without the intracavity SRS. Good 
agreement with the numerical integration of the rate equation model has been 
found not close to the Stokes pulse generation threshold. The obtained analyt-
ical expressions have been applied for the Cr4+:YAG Q-switched Nd:LSB mi-
crochip solid state lasers (SSLs) with the Ba(NO3)2 Raman medium. The ana-
lytical results correlate with the experimental data. 
The analytical expressions and results of this investigations are applicable 
(under the used approximations) for any Q-switched laser with intracavity 
Raman conversion. They will be valid until the analytical solution for identi-
cal laser without the intracavity Raman conversion persists to be valid. The 
validity of the analytical results should be revisited when the Stokes pulse du-
ration will be on the time scale of the transverse relaxation time of the vibra-
tional modes in the Raman medium. In solid state Raman media this relaxa-
tion time is in the range from few to tens pisoseconds, hence for the microchip 
SSLs this gives the validity of the analytical results up to the subnanosecond 
time scale. 
Derived analytical expressions can be applied either when the stimulated 
emission of the FL photons and their Raman conversion occurs in single me-
dium (self-Raman conversion) or when the gain and Raman active media are 
different. They can be used to find and optimize the peak power, output ener-
gy, and time durations of the FL and Stokes pulses. 
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Analytical solution for pulse evolution in Q-switched lasers with intracavity Raman conversion

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Analytical solution for pulse evolution in Q-switched lasers with intracavity Raman conversion

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