Abstract
Modelocked lasers constitute the fundamental source of optically-coherent ultrashort-pulsed radiation, with huge impact in science and technology. Their modeling largely rests on the master equation (ME) approach introduced in 1975 by Hermann A. Haus. However, that description fails when the medium dynamics is fast and, ultimately, when light-matter quantum coherence is relevant. Here we set a rigorous and general ME framework, the coherent ME (CME), that overcomes both limitations. The CME predicts strong deviations from Haus ME, which we substantiate through an amplitude-modulated semiconductor laser experiment. Accounting for coherent effects, like the Risken-Nummedal-Graham-Haken multimode instability, we envisage the usefulness of the CME for describing self-modelocking and spontaneous frequency comb formation in quantum-cascade and quantum-dot lasers. Furthermore, the CME paves the way for exploiting the rich phenomenology of coherent effects in laser design, which has been hampered so far by the lack of a coherent ME formalism.
Highlights
Modelocked lasers constitute the fundamental source of optically-coherent ultrashort-pulsed radiation, with huge impact in science and technology
We refer to superfluorescence and other coherent effects in modelocking which give rise to coherent ringing and hyperbolic-secant-shaped pulses shorter than predicted by the standard Siegman-Haus theory[10,11,12,13,14], self-induced transparency modelocking which exploits coherent dynamics of the atomic gain medium and saturable absorber[15,16,17], Rabi flopping in quantum-cascade lasers[18], spontaneous modelocking via the Risken-Nummedal
The rich and interesting phenomenology arising from coherent effects in lasers currently lacks a master equation (ME) formalism, and this situation has probably hindered the deployment of such effects in laser design
Summary
Modelocked lasers constitute the fundamental source of optically-coherent ultrashort-pulsed radiation, with huge impact in science and technology. We refer to superfluorescence and other coherent effects in modelocking which give rise to coherent ringing and hyperbolic-secant-shaped pulses shorter than predicted by the standard Siegman-Haus theory[10,11,12,13,14], self-induced transparency modelocking which exploits coherent dynamics of the atomic gain medium and saturable absorber[15,16,17], Rabi flopping in quantum-cascade lasers[18], spontaneous modelocking via the Risken-Nummedal-. Graham-Haken (RNGH) instability[19,20] and superfluorescent and superradiant effects in semiconductor lasers[21], and heterostructures[22], giving rise to superluminal pulse propagation All those coherent and cooperative effects in lasers have been modeled using the full set of Maxwell–Bloch equations[5,19,23,24], which hinders analytical treatments and results in heavy simulation processes. A coherent ME (CME) theory would allow simple but rigorous description of laser operation in the presence of coherent effects, potentially paving the way to the development of new classes of laser systems that exploit light-matter coherence
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