[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Superradiance as a Way to the Steady-State Multimode and Ultrashort Pulsed Lasing in CW Quantum-Dot Heterolasers

摘要： On the basis of the Maxwell-Bloch equations, we demonstrate theoretically and numerically that the pulsed superradiant lasing is possible in the quantum-dot heterostructures under continuous-wave (CW) optical pumping if the quantum-dot coherence lifetime exceeds the photon lifetime in a laser cavity [1, 2]. We analyze/compare in detail and select the most promising multilayered well-dot and sub-monolayer quantum-dot heterostructures which could be used as the active media, and design for them the proper low-Q combined Fabry-Perot cavities with distributed feedback which will select the superradiant modes. We investigate various operational regimes of the superradiant lasing and the intriguing quantum-coherent features of both cooperative and individual dynamics of quantum dots under the action of a self-consistent intracavity field preserving the long-term and wide-spectral coherence. Among the remarkably diverse operational regimes of the laser, we find the quasi-stationary, self-modulated, regular or irregular pulsed, self-locked, and stochastic regimes. In particular, we show that one or several superadiant modes may emit the quasiperiodic sequences of ultrashort subpicosecond pulses with comparable periods of the order of picoseconds and at the same time give rise to many steady-state modes with quasi-equidistant spectrum (see a fig. 1). The letter used to be self-locked due to the superradiant coherent dynamics of quantum dots, so that an additional sequence of ultrashort subpicosecond pulses with a round-trip period are emitted in the absence of any active or passive mode-locking elements. We indicate the ways how (i) to overcome an additional relaxation of the quantum-dot coherence in the presence of incoherent pumping and suppression of the superradiant gain within an inhomogeneously broadened spectral line of quantum dots continuously, i.e., during the entire time of laser operation, and (ii) to ensure a fully cycling pump-emission scheme of the quantum dots’ dynamics including a fast depletion of the lower-energy states under a CW pumping of the upper-energy states and to minimize extra heating which accompanies this cycling process and increases the relaxation of coherence. The suggested pulsed multimode superradiant heterolaser will offer a number of applications in the information optics, data processing, fiber network systems, wideband dynamic spectroscopy and diagnostics of various materials since it will be the first compact source of coherent radiation with a wide variety of controllable quantum-correlation and spectral-temporal properties. Also, such a heterolaser is a unique object for the studies of complex coherent processes in the semiconductor heterostructures.