A N Shelaev

Optical Bistability And Hysteresis In A Solid State Ring Laser

The phenomena of optical bistability, hysteresis and memory under the interaction of oppositely directed (OD) light waves in a CW YAG:Nd3+ solid state ring laser (SRL) have been experimentally discovered. The possibilities of spontaneous or forced (with modulated SRL parameters) commutation of the radiation direction without transients at the relaxation frequency (typical for solid state lasers) have been established both in the single-mode and in the mode-locking regimes with various feedback circuits. The mode-locking band was found to be substantially broadened by more than an order of magnitude when OD light waves primarily diffracted on a standing ultrasonic wave were returned into the acousto-optical modulator. With such acousto-optical feedback the mode-locking regime has been obtained using a modulator on a running ultrasonic wave.

Utilization of competition between counterpropagating waves for modulation and stabilization of the radiation emitted from a ring laser

Theoretical and experimental investigations were made of the possibility of increasing the efficiency of intracavity modulation and stabilization of the radiation emitted from ring lasers by utilization of the competition between counterpropagating waves. It was established that in the case of solid-state ring lasers one can switch rapidly the direction of counterpropagating waves both in the case of forced mode locking and in the case of single-mode emission without spike transient processes at a relaxation frequency typical of solid-state lasers. An analysis was made of the conditions for significant reduction of the switching time and a method is suggested for achieving this by simultaneous modulation of the amplitude nonreciprocity and of the coupling between counterpropagating waves. It is shown that highly stable unidirectional single-mode operation of a solid-state ring laser can be achieved as a result of weak modulation of the resonator perimeter. Various time dependences of the intensities of counterpropagating waves and stabilization of bidirectional operation of a solid-state ring laser were achieved using a magnetooptic feedback loop.

The Effect Of Intraresonator Nonlinear Optical And Magneto-Optical Phenomena Upon The Competitive Interaction Of Oppositely Directed Light Waves

It is found experimentally that the competitive interaction of the oppositely directed (OD) light waves in YAG:Nd3+ and ruby solid-state ring lasers OIRL) can be significantly reduced due to nonlinear optical effects (second harmonic generation, stimulated Raman scattering, resonant absorption) since the nonlinear losses for the wave of lower intensity are lower. It was established that in the SRL with a resonantly absorbing medium the spatially inhomogeneous burning-out and the slowness of the relaxation of the inverted population in the solid-state active medium may result in strong phase nonreciprocity due to the frequency shift of the OD waves after their reflection from the moving lattice of the inverted population. The beat frequency strongly depends on detuning between the gain and absorption lines and may be more than two orders of magnitude less in comparison with the resonator frequency difference in the rotating SRL. The possibility has been shown of active stabilization of the bidirectional generation in the beat regime using the nonreciprocal amplitude Faraday element controlled by the external feedback circuit via the difference of the OD waves intensities.