Graphene-Based Active Random Metamaterials for Cavity-Free Lasing.
Manipulating and controlling the optical energy flow inside random media is a research frontier of photonics and the basis of novel laser designs. Here, we show that a metamaterial consisting of randomly dispersed graphene nanoflakes embedded within an optically pumped gain medium (rhodamine 6G) can operate as a cavity-free laser thanks to its extraordinarily low threshold for saturable absorption. The emitted light is self-organized into a well-determined spatial pattern, which depends on the graphene flake density and can be externally controlled through the optical pump. We provide different examples of tunable laser operation ranging from stable single-mode to chaoticlike behavior. Our metamaterial design holds great potential for the optical control of light amplification, as well as for the development of single-mode beam-engineered cavity-free lasers.
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain.
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Marini
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain.|ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain.
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