Contents lists available at ScienceDirect Optical Materials journal homepage: www.elsevier.com/locate/optmat Rare earth doped PDMS elastomeric random lasers A.R. Hlil a,b,e,* , B.C. Lima c , J. Thomas a , J.-S. Boisvert a , H. Iden e , Y. Garcia-Puente a , L.J.Q. Maia f , Y. Ledemi e , Y. Messaddeq e , A.S.L. Gomes c , R. Kashyap a,d a Fabulas Laboratory, Department of Physics Engineering, École Polytechnique Montréal, P.O Box 6079, Station Centre-ville, Montreal, QC, H3T 1J4, Canada b Département de chimie, Faculté des sciences et de génie Pavillon Alexandre-Vachon, 1045, avenue de la Médecine, Université Laval, Québec, G1V 0A6, Canada c Departamento de Física, Universidade Federal de Pernambuco, Recife-PE, Brazil d Fabulas Laboratory, Department of Electrical Engineering, École Polytechnique Montréal, P.O Box 6079, Station Centre-ville, Montreal, QC, H3T 1J4, Canada e Centre d’Optique, Photonique et Laser, 2375 Rue de la Terrasse, Université Laval, Québec, QC, G1V 0A6, Canada f Grupo Física de Materiais, Instituto de Física, Universidade Federal de Goiás-UFG, Campus II, Av.Esperança 1533, 74690-900, Goiânia, GO, Brazil ARTICLE INFO Keywords: Elastomeric random laser PDMS Nd YAB nanoparticles Levy-like statistics ABSTRACT We report a very stable elastomeric random laser (SERL) system composed of two stable materials: inorganic Nd: YAB nanoparticles and polydimethylsiloxane (PDMS). Lasing at a wavelength of 1064.5 nm is observed when the samples are exposed to pulsed nanosecond excitation at 808 nm or 532 nm, with long term (days) operation without degradation. Contrary to other RLs based on polymers, this very stable RL is the first elastomeric system, hence tunable, which allows the systematic investigation of its dynamics over a long time, without the com- plication of gain reduction or deterioration of the polymer. The RL threshold is estimated to be around 1.0 mJ at 808 nm. The measured linewidth decreases from 3.2 nm to 0.5 nm. The spectral peak position as well as the intensity is conveniently tuned by stretching the elastomer polymer composite. As an application which requires long term operation, Levy-like statistics and replica symmetry breaking in this open cavity random laser were also demonstrated. These lasers have been used over several months without noticeable degradation. 1. Introduction Lasing in random nanostructures based on the different feedback and gain mechanism has been extensively investigated during the past decades in various materials such as dye-doped liquid crystals, semi- conductor nanostructures, polymers etc. [1–3]. Random lasers work on the principle of multiple scattering with incorporated gain or separated gain in a dense media [4]. One of the challenges related with the random lasers is the tunability of the lasing emission owing to the ab- sence of a well-defined cavity. The utilization of a stretchable substrate is a feasible method to generate tunable random lasers, and we recently reported our initial findings of an elastomeric RL system [5]. Another flexible materials system has also been reported on but with dyes, which are intrinsically short lived [2,3,6]. Stimulated emission has been demonstrated in different semiconducting polymer films such as func- tionalized polyphenylenevinylene (PPV), p-polyphenylene (PPP), and polyfluorene (PF) derivatives representing a wide variety of molecular structures with emission wavelengths covering almost the entire visible range [7]. The mechanical, electronic and optical properties of poly- mers can be easily modified by chemical substitutions or by doping techniques. These advantages along with the stability of the matrix can lead to tunability of random lasers emission originating from the stretching of polymers [5,6]. We have been able to explore the tun- ability aspects of the RL system under different pumping regimes by stretching the PDMS composite, as well as explore the multi-direc- tionality and multi-wavelength emission, using the same sample re- peatably, something that has not been possible before. The random laser properties of Nd: YAB (Nd x Y 1-x Al 3 (BO 3 ) 4 , with 0.05 ≤ x ≤ 1.00, nanocrystals (powder form) excited by a pulsed laser operating at 808 nm were previously investigated [8–11] showing several emission lines in the ultraviolet - near infrared range (340–1062 nm), depending on the excitation wavelength (700–900 nm), with the nanoparticles acting also as self-scattering media. Our recent work demonstrated a new material system using Nd: YAB (NdxY 1-x Al 3 (BO 3 ) 4 ) nanoparticles with different concentrations of Neodymium and Rhodamine 6G incorporated in Polydimethylsiloxane (PDMS) polymer to evaluate their influence on random lasing [5]. In this work we report on a detailed study of random laser (RL) emission from elastomer polymeric composite films which contains Nd: YAB (Nd 0.8 Y 0.2 Al 3 B 4 O 12 ) nanoparticles when pumped with pulsed https://doi.org/10.1016/j.optmat.2019.109387 Received 11 July 2019; Received in revised form 15 August 2019; Accepted 14 September 2019 * Corresponding author. Fabulas Laboratory, Department of Physics Engineering, École Polytechnique Montréal, P.O Box 6079, Station Centre-ville, Montreal, QC, H3T 1J4, Canada. E-mail address: antsar.hlil@polymtl.ca (A.R. Hlil). Optical Materials 97 (2019) 109387 0925-3467/ © 2019 Elsevier B.V. All rights reserved. T