Theoretical simulation on the Mechanism of Laser Gain Competition in Multi-Order Solid-State Raman Lasers

To reveal the dynamic characteristics and energy transfer mechanisms of multi-order Raman lasers, we established a set of rate equation groups for first-order, second-order, up to third-order Stokes and first-order Stokes frequency doubling Raman lasers by introducing the rate term of Raman photon number density variation, the spontaneous/stimulated Raman scattering term into the traditional rate equation. Using numerical simulations, we systematically analyzed the dynamic evolution of the intra-cavity population inversion density, as well as the photon number densities of the fundamental frequency laser, each-order Stokes laser, and second-harmonic laser. To address the problem of Raman gain competition caused by multiple orders of Stokes laser sharing the same Raman gain medium and resonator, we proposed a cascaded coupling cavity scheme to suppress this phenomenon, which can provide theoretical basis for achieving high-power and high-spectral-purity Raman laser output.