Periodically-pumped organic microlasers

• Applicant: Professor Dr. Karl Leo
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 236150641

• Final Report Year: 2017

Final Report Abstract

Within the framework of this project, we have shown, that the in-plane potential can be engineered in all-optical way via minimal perturbation of optical properties of organic cavity layer using structured optical pump fields. This causes adjacent individual microlasers to couple in phase, which in turn leads to a multimode laser emission in energy and space domain. The induced in-plane wave vector components lift off an inherent and fundamental limit of a lasing mode volume and brings about lateral coherence over the whole cavity layer virtually without any limits. As a consequence, the oblique modes evolve faster in time and tend to show enhanced internal quantum efficiency as well as lower lasing thresholds with respect to the conventional OVCSEL mode. In order to overcome limitations of interferometric optical structuring and get to the micrometer and sub-micrometer periodicities, we produced our conventional organic microcavities on prestructured substrates. In these samples, formation of mode structure is due to an in-plane modulation of effective refractive index but is still based on diffraction phenomenon of light on the underlying index grating. In a very extreme case, the in-plane index grating operates as a second-order DFB structure, which is energetically matched to the organic VCSEL. Such a cross-coupled composite-cavity organic microresonator possess very unusual and specific features, which are not present in conventional microresonators, and provide a promising platform for photonic circuits based on organic microlasers. It is getting increasingly recognized that the photonic confinement is a key process in the systems, where photons form a quasiparticles, for example, exciton-polaritons, where the excitons and cavity photons are strongly coupled and their lifetimes are well matched. It is hard to achieve this in the Alq3 :DCM based cavities and, therefore, they operate as a pure photonic system. We note, however, a striking similarity in the far-field emission patterns of strongly-coupled exciton-polariton systems and those which were obtained in this work in a pure photonic regime. This confirms the importance of photonic confinement and allows to apply our findings, obtained within the framework of this project, to the confined strongly-coupled exciton-polariton systems.

Publications

• “Photonic confinement in laterally structured metal-organic microcavities,” Appl. Phys. Lett., vol. 105, no. 5, p. 051108, 2014
  A. Mischok, R. Brückner, M. Sudzius, C. Reinhardt, V. G. Lyssenko, H. Fröb, and K. Leo
  
• “Zero- and π-states in a periodic array of deep photonic wires,” Adv. Optical Mater., vol. 2, pp. 746–750, 2014
  A. Mischok, V. G. Lyssenko, R. Brückner, F. Löchner, R. Scholz, A. A. Zakhidov, H. Fröb, and K. Leo
  
• “Control of lasing from Bloch states in microcavity photonic wires via selective excitation and gain,” Phys. Rev. Applied, vol. 3, no. 6, p. 064016, 2015
  A. Mischok, R. Brückner, H. Fröb, V. G. Lyssenko, K. Leo, and A. A. Zakhidov
  
• “Photonic lattices in organic microcavities: Bloch states and control of lasing,” Proc. SPIE, vol. 9566, Organic Light Emitting Materials and Devices XIX, 95660T, 2015
  A. Mischok, R. Brückner, H. Fröb, V. G. Lyssenko, and K. Leo
  
• “Cross-coupled composite-cavity organic microresonators,” Appl. Phys. Lett., vol. 109, p. 043302, 2016
  T. Wagner, M. Sudzius, A. Mischok, H. Fröb, and K. Leo
  
• “Lasing and macroscopic coherence of hybridized modes in coupled 2D waveguide-VCSEL resonators,” Adv. Optical Mater., vol. 4, no. 8, pp. 1215–1221, 2016
  A. Mischok, T. Wagner, R. Brückner, M. Sudzius, H. Fröb, V. G. Lyssenko, and K. Leo
  
• “Lasing and macroscopic coherence of periodic 2D and 3D microstructures in organic microcavities,” Proc. SPIE, vol. 9941, Organic Light Emitting Materials and Devices XX, 99411H, 2016
  A. Mischok, T. Wagner, R. Bückner, M. Sudzius, H. Fröb, V. G. Lyssenko, and K. Leo
  
• “Net gain in small mode volume organic microcavities,” Appl. Phys. Lett., vol. 108, p. 023304, 2016
  C. Tzschaschel, M. Sudzius, A. Mischok, H. Fröb, and K. Leo