The nonreciprocity of the characteristics of counterpropagating waves in a ring resonator formed by totally reflecting prisms is analysed. The polarisation-inhomogeneous properties of a prism resonator and their effect on the nonreciprocity of the frequencies of counterpropagating waves are studied.
The mutual interaction of counterpropagating waves in a ring resonator containing a medium with second-order dispersive nonlinearity is studied. The theoretical treatment of nonreciprocal propagation is based upon the novel coupling of counterpropagating and mode-locked first- and second-harmonic waves. The experimentally observed transfer characteristics of a high-frequency model system reveal a directionally asymmetric bistability. This nonreciprocity can also be attributed in the time domain to the occurrence of dissipative structures, i.e., to solitons traveling within the resonator.
A nonreciprocal ring optical resonator with the simplest type of nonuniformity in the form of two interacting scatterers is considered. A boundary problem of a periodic type allowing one to write the characteristic equation for determining eigenfrequencies is formulated. Analytic expressions for eigenfrequencies and the distribution coefficient of travelling waves in the mode are derived under the assumption of relative smallness of the reflection coefficient and the nonreciprocity parameter. The peculiarities of splitting these frequencies and the structure of the eigenfrequencies (resonator modes) corresponding to them are discussed.
Narrow resonances of the intensities and oscillation frequencies of counterpropagating waves in the vicinity of the center of the quantum transition in a pure-isotope ring gas laser have been studied. It is shown that the origin of resonances is related to the presence of sources causing unequal losses and/or frequencies of the counterpropagating waves in the laser cavity. The resonance change of intensities, which is accompanied by the resonance behavior of the medium dispersion for each of the waves, is not related to resonance changes of the saturated gain coefficients of the nonlinear medium. The resonances are caused by the redistribution of energy between the waves. The character of resonance changes of frequencies and intensities depends on the nature of nonreciprocity present in the cavity.
A substantial enhancement (by orders of magnitude) of the Sagnac effect in a passive ring resonator can be attained by using a nonreciprocal feedback. This feedback is based on the nonreciprocal element controlled by the signal proportional to the difference between intensities of counterpropagating waves, and is an optoelectronic analog of nonlinear nonreciprocity proposed by us earlier. Under some critical conditions, this system can exhibit directional bistability and directional switching of the counterpropagating waves.