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Going beyond traditional cavity-concepts, recently conceived nanolasers employ plasmonic resonances for feedback, allowing them to concentrate light into mode volumes that are no longer limited by diffraction [1]. The use of localized surface plasmon resonances as cold-cavity modes, however, is only one route to lasing on subwavelength scales. Lasing, in fact, does not require modes predefined by geometry but merely a feedback mechanism [2].
Here we demonstrate that the concept of dispersion-less stopped-light [3] allows by combination of nanoplasmonics with quantum gain materials [4] stopped-light lasing in hybrid nanoplasmonic heterostructures. Thereby, photons are trapped and amplified in space just at the point of their emission. It will be discussed that, at the stopped-light point, a stable lasing mode can form over a finite region of gain material due to the arising local (cavity-free) feedback in the form of a sub-wavelength optical vortex. We discuss the remarkable spatio-temporal dynamics of nanoplasmonic stopped-light lasing is studied on the basis of a Maxwell-Bloch Langevin approach [4]. Moreover, a new rate-equation framework is shown to grasp the particular physics of stopped-light lasing involving [4]. The observed high-β characteristics and picosecond relaxation oscillations of cavity-free stopped-light lasing can potentially allow for the design of thresholdless plasmonic laser diodes that can be modulated with THz speeds.
References
[1] O Hess and KL Tsakmakidis, Science 339, 654 (2013).
[2] J M Hamm and O Hess, Science 340, 1298 (2013).
[3] KL Tsakmakidis, TW Pickering, JM Hamm, AF Page and O Hess, Phys Rev Lett 112, 167401 (2014).
[4] T Pickering, J M Hamm, A F Page, S Wuestner and O Hess, Nature Communications 5, 4971 (2014).
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