1295 ISSN 1063-7826, Semiconductors, 2019, Vol. 53, No. 10, pp. 1295–1303. © Pleiades Publishing, Ltd., 2019. Russian Text © The Author(s), 2019, published in Fizika i Tekhnika Poluprovodnikov, 2019, Vol. 53, No. 10, pp. 1329–1339. Features of the Simultaneous Generation of Low-Q and High-Q Modes in Heterolasers Based on Quantum Dots with a Long Incoherent Relaxation Time of Optical Dipole Oscillations E. R. Kocharovskaya a,b, *, A. V. Mishin a,b , I. S. Ryabinin a,b , and V. V. Kocharovsky a,b a Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, 603950 Russia b Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603950 Russia *e-mail: katya@appl.sci-nnov.ru Received April 24, 2019; revised April 29, 2019; accepted April 29, 2019 Abstract—The features of the multimode steady-state generation of superradiant heterolasers, in which quan- tum dots with a long incoherent relaxation time serve as an active medium, while low-Q combined Fabry– Perot cavities with a distributed feedback of counter-propagating waves serve as cavities, are studied. It is shown that due to the quantum-coherent dynamics of optical dipole oscillations and population inversion of the working levels in a quantum-dot ensemble with strong inhomogeneous broadening of the spectral line, the simultaneous lasing of modes with various degrees of phasing and/or correlation and with qualitatively different dynamic behavior, notably, quasi-stationary, metastable, self-modulation, pulse-periodic, and quasi-chaotic is possible. Keywords: superradiant heterolaser, low-Q combined cavity DOI: 10.1134/S1063782619100099 1. INTRODUCTION According to modern notions of laser physics and the achievements of semiconductor nanotechnolo- gies, it is possible to expect the attainment of the simultaneous generation of low-Q, mid-Q, and high- Q modes with different characters of the nonstationary behavior under the conditions of continuous pumping of a series of heterostructures based on quantum dots, especially submonolayer and well dots with a com- bined cavity corresponding to the Fabry–Perot scheme in the presence of the distributed feedback of waves [1–3]. This work is devoted to the simulation of similar multimode dynamics based on spatially one-dimen- sional Maxwell–Bloch equations [3–7] in the approx- imation of a two-level active medium with strong inhomogeneous broadening of the spectral line and rather weak incoherent relaxation of optical dipole oscillations of the separate active center (quan- tum dot; T 2 is the corresponding lifetime of these oscillations). More precisely, the last condition means that the laser cavity should provide the presence of modes with a very different Q-factor—low, mid, and high, for which the field decaying rate in the absence of the population inversion of active centers is considerably larger, on the order of, or considerably smaller than the mentioned polarization rate , respectively. The goal of our work is to show the possi- bility of the simultaneous generation of all three types of modes having substantially different values of the Q-factor and, consequently, the character of the time- dependent behavior and resonant interaction with active centers. The multimode radiation formed by such heterola- sers with the efficient continuous pumping of quan- tum dots can possess unique spectral-correlation properties not characteristic of existing semiconductor heterolasers [6–12], where complex pulsed or quasi- chaotic emission is possible in the multimode regimes with the special phazing and switching of modes, but all modes usually generate in the quasi-stationary or self-modulation mode and are high Q in the sense of the ≪ inequality. As for the heterolasers that we propose, they include the generation of low-Q superemitting modes introducing new quantum- coherent features into the self-consistent dynamics of the field, polarization, and population inversion of the active medium. Herewith, although the radiation of separate low-Q and mid-Q modes is formed by spe- cific spectrally localized quantum-dot ensembles, the strong self-modulation of a considerable part of the modes and their nonlinear interaction take place. The latter can cause the involvement of numerous modes, -1 2 * T -1 2 T -1 E T -1 2 T -1 E T -1 2 T XXIII INTERNATIONAL SYMPOSIUM “NANOPHYSICS AND NANOELECTRONICS”, NIZHNY NOVGOROD, MARCH 11–14, 2019