Continuous lasing for perovskites

Optically generated local phase changes in methylammonium lead iodide produce a transient quantum well structure with robust optical gain. The result is a perovskite laser that supports continuous-wave lasing under optical pumping.PostprintNon peer reviewe

Advances in small lasers

M.T.H was supported by an Australian Research council Future Fellowship research grant for this work. M.C.G. is grateful to the Scottish Funding Council (via SUPA) for financial support.Small lasers have dimensions or modes sizes close to or smaller than the wavelength of emitted light. In recent years there has been significant progress towards reducing the size and improving the characteristics of these devices. This work has been led primarily by the innovative use of new materials and cavity designs. This Review summarizes some of the latest developments, particularly in metallic and plasmonic lasers, improvements in small dielectric lasers, and the emerging area of small bio-compatible or bio-derived lasers. We examine the different approaches employed to reduce size and how they result in significant differences in the final device, particularly between metal- and dielectric-cavity lasers. We also present potential applications for the various forms of small lasers, and indicate where further developments are required.PostprintPeer reviewe

Dip-pen patterning of poly(9,9-dioctylfluorene) chain-conformation-based nano-photonic elements

Metamaterials are a promising new class of materials, in which sub-wavelength physical structures, rather than variations in chemical composition, can be used to modify the nature of their interaction with electromagnetic radiation. Here we show that a metamaterials approach, using a discrete physical geometry (conformation) of the segments of a polymer chain as the vector for a substantial refractive index change, can be used to enable visible wavelength, conjugated polymer photonic elements. In particular, we demonstrate that a novel form of dip-pen nanolithography provides an effective means to pattern the so-called β-phase conformation in poly(9,9-dioctylfluorene) thin films. This can be done on length scales ≤500 nm, as required to fabricate a variety of such elements, two of which are theoretically modelled using complex photonic dispersion calculations

Laser Emission from Self-Assembled Colloidal Crystals of Conjugated Polymer Particles in a Metal-Halide Perovskite Matrix

Here, we present a hybrid organic/inorganic photonic composite, which generates laser emission from the organic material after pumping the inorganic component. The composite consists of a methylammonium lead-halide perovskite matrix CH3NH3Pb(BrxCl(1-x))3 and monodisperse poly(fluorene-co-divinylbenzene) particles, which have excellent optical feedback and gain. Micrometer-sized conjugated polymer particles (CPPs) are deposited together with the perovskite precursor from solution using a single-step vertical deposition method. The particles self-assemble into a photonic crystal and the perovskite forms an inorganic matrix in the interstitial space. Energy transfer to the polymer particles after optically pumping the metal-halide perovskite is studied in two systems with different halide ratios in the perovskite (Br to Cl: 1/9 and 4/6) to control the overlap of the perovskite emission energy with the absorption of the particles. From time-resolved photoluminescence experiments, we observe nonradiative energy transfer from the perovskite to the particle in both coassemblies; however, increased spectral overlap of perovskite emission and particle absorption enhances energy transfer efficiency by 37%. Because of the ordered assembly of the CPPs, we observe laser emission after energy transfer from the Cl-rich perovskite matrix at fluences of 13 mJ/cm2. Our report of a hybrid material system that combines the excellent opto-electronic properties of metal-halide perovskites with the outstanding optical properties of conjugated polymers represents a new approach and progress in the pursuit of electrically pumped polymer lasers