2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/226298New critical surfaces have been analytically found for a 3D vectorial model of bistable pumping system of an optical-wavelength acoustic laser (phaser). The Lyapunov instability is possible for this pumping system at the upper branch for a high quality factor Qc of a pump resonator: Qc/Qm >> 1, where Qm is the magnetic quality factor. This instability is of great interest for interpretaion of some experimental data on the optical-wavelength ruby phaser (see our previous papers arXiv:cond-mat/0303188, arXiv:cond-mat/0402640, arXiv:0704.0123, arXiv:0901.0449).10 pages, no figures. Ver.2: references to masers with high-quality (whispering-gallery) resonators addedOther Condensed MatterExactly Solvable and Integrable SystemsOpticstext