It has been established both experimentally and theoretically that in YAG:Nd$^{3+}$ solid-state ring lasers (SRLs) with strong competition and nonlinear coupling of counter-running waves (CRW) there exists, due to CRW self-diffraction on induced inverted-population gratings, an unusual (for laser physics) effect of ultralow-frequency instability in both uni- and bidirectional lasing when the radiation-direction commutation frequency is lower than the lowest-frequency SRL parameter, the rate of inverted-population relaxation $1/T_1$, by a factor of $10^5$ or more (commutation period Tc longer than $T_k>10^2$ s).
Research Institute of Nuclear Physics, Department of Solid-State Physics, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
Science News of the Faculty of Physics, Lomonosov Moscow State University
This new information publication, which is intended to convey to the staff, students and graduate students, faculty colleagues and partners of the main achievements of scientists and scientific information on the events in the life of university physicists.