Study On Multi Frequency Shift Synchronous Oscillator Intracavity Sum-frequency Pulsed Raman Laser

The yellow-green laser in the range of 560～600 nm has a wide range of applications in biomedicine,military detection,information storage,astronomy,etc.,and has a strong practicability.The sum-frequency Raman laser is an effective method to obtain the yellow-green laser,and the laser-rate-equations are an effective theoretical tool to analyze the operation of the laser.In this paper,by use of laser diode pumping,we use a c-cut Nd:Gd VO₄or Nd:YVO₄as self-Raman medium,a YVO₄or Gd VO₄crystal as Raman medium,and an LBO crystal as sum-frequency medium in active or passive Q-switching laser configuration,which corresponds to the three-frequency-shift Stokes optical synchronous oscillation of two kinds of Raman crystal main frequency shift(882cm^-1→YVO₄/890 cm^-1→Gd VO₄)and the common 259 cm^-1secondary frequency shift.In this paper,the primary frequency-shifted first-order Stokes laser and the secondary frequency-shifted first-order Stokes sum-frequency hybrid pulse Raman laser are theoretically studied,and the passive laser is experimentally studied.In terms of theoretical research,a theoretical model of three-Raman-shift synchronous oscillating pulse intracavity sum-frequency pulsed Raman laser based on the laser rate equations is constructed.In this theoretical model,the inversion population distribution is Top-Hat distribution,and the intracavity lasers is a TEM₀₀fundamental mode in Gaussian distribution.The generation of cascaded Stokes light with secondary Raman-shift in the two crystals is considered,and the effect of thermal effect on the laser operation and the stability of the cavity shape are considered.The output characteristics of 568 nm sum-frequency light under active or passive Q-switching are simulated.With a compact line cavity structure,the passively Q-switched c-cut LBO sum-frequency-mixed Nd:Gd VO₄/YVO₄multiple Raman-shift laser in experimentally investigated.At a T₀of83%,at 5.09 W of the incident pump power,a 67 m W yellow-green laser at 568 nm is obtained,with an optical-to-optical conversion efficiency of 1.3%and a pulse width of 5.8ns.