New type of breathers near Fermi resonance of optical oscillations in crystals

Abstract

It has been shown that in crystals, near the Fermi resonance of optical excitons, in addition to the solitons discovered before, such as multi-exciton bound complexes of cusp-, crater-, and dark-type possessing a single carrier frequency, amplitude, and envelope, there are nonlinear soliton excitations of a crucially new, breather-type. Such periodic soliton oscillations exhibit slowly pulsing amplitudes of high-frequency oscillations, with the carrier frequency being a multiple of the frequency of pulsations. In accordance with the multiplicity, the depth of pulsations defines a series of the carrier frequencies, which are condensed near the basic frequency of optical oscillations. The spatial dependence of the two envelopes of new solitons of the cusp type is determined. With the increase in multiplicity, the sharpness of the space envelope of a soliton decreases, while the localization radius increases. Some other features of the solitons of new type are listed.