Riccardo Sapienza – from Imperial’s Physics Department will be talking about some of his recent experiments on:
Title: Nanophotonic lasers on a graph
Abstract: Random lasing – for which disorder is exploited to enhance stimulated emission has emerged as a paradigmatic phenomenon of complex lasers[1]. In this talk I will discuss our recent efforts to control laser light emission in unconventional laser architectures, where light flows and get amplified on a random graph, supported by a material nanostructured sub-wavelength networks[2]. The network is composed of interconnected polymer nanofibers that are doped with a laser dye. Network lasers offer the advantage of strong modal competition for the gain, a property that can be exploited for control and tuning. In particular networks can be modelled with a graph description of Maxwell’s equations, and the lasing action by a steady-state ab initio laser theory(netSALT)[3].
We demonstrate lasing from the network, over a wide range of frequencies corresponding to many Anderson localised network modes, which can be analysed using the results of random matrix theory. I will also discuss how unbalancing the mode competition is an effective strategy for spectral control and signal processing. The complexity of the photonic network lasers brings the opportunity to single-out a lasing frequency out of the spectral haystack by selectively illuminating a very small subset of the network links.
[1]Determining random lasing action, R. Sapienza Nature Review Physics,1, 690 (2019)
[2]A nanophotonic laser on a graph, M.Gaio, D. Saxena, J. Bertolotti, D. Pisignano, A. Camposeo, R. Sapienza, Nature Comm. 10, 226 (2019)
[3] Steady-state ab initio laser theory on a graph, A. Arnaudon, D. Saxena, S. Yaliraki, M.Barahona, R. Sapienza, in preparation.