Resonant processes of periodic mode alternation in stimulated microwave phonons emission spectra

Mode Competition and Anomalous Cooling in a Multimode Phonon Laser

“…Following the observation of phonon amplification in microwave-pumped ruby [1] in 1964, the possibility of "phonon lasing" was suggested. Subsequent work in ruby studied the emission spectrum of phonon generation [2] and multimode processes [3]. With the advent of optical pumping, detailed studies of the coherence of phonon emission were enabled [4], culminating in a ruby "saser" [5].…”

A nonlinear dynamics of stimulated phonon emission in a nonautonomous acoustic quantum generator under superlow-frequency-modulated pumping conditions

“…It should be emphasized that the above-described self- detunings in the phonon spectra of a nonautonomous phaser, as well as the recently observed nonlinear phenomena in electromagnetic masers [18] and autonomous acoustic quantum generators [16,19], possess an essentially nonthermal nature. Although the lower characteristic frequencies of the motions observed in this study fall within a millihertz frequency range, all these motions are related to the microwave field self-action through a spin system of a paramagnet in the absence of the socalled phonon bottleneck effect [20] (and of the resulting phonon avalanche [21]).…”

“…This resonance leads to a manifold narrowing of the microwave spectrum of stimulated phonon emission and to the appearance of very slow, highly organized self-detunings of phaser generation at still lower frequencies depending on the parameter ∆ L ≡ ω m − ω L . Some preliminary results on superlow-frequency resonance were reported in [12], and short version of this study was published in [13] and repoted in [14]. …”

“…Moreover, in the entire region of |∆ H | < 10 Oe, even the ω L value remains virtually the same (close to 9.8 Hz). Only for a still greater detuning of the spin system with respect to the magnetic field (under these conditions, even an autonomous phonon laser may exhibit some insufficiently studied generation features [16]), the resonance frequency ω L begins to drop significantly (approximately by half for |∆ H | < 60 Oe). Here the stimulated phonon emission intensity drops by more than one order of magnitude because of a decrease in the level of pumping (which passes now via a wing of the paramagnetic resonance line).…”

“…Several features of observed cooperative alternation of resonant LA modes in phonon laser may be described by simple balance model of active medium with spatial hole burning [10], but detailed theory of the selforganization in phaser must include into consideration the electron-nuclear magnetic interactions [23]. These interactions dramatically modify the processes of nearresonant energy transfer in ruby phaser [7,24] due to nuclear spin polarization under conditions of electron spinsystem saturation.…”