An ultralow-cost fabrication method uses an inkjet printer to produce “lasing capsules” for external-cavity vertically emitting thin-film organic lasers, a development that could enable disposable laser chips. One obstacle that has limited widespread adoption of organic lasers is the fact that they degrade relatively quickly, which could be overcome if the lasers are inexpensive enough to dispose upon failure. Inkjet-printed lasing capsules serve as the core of an organic laser. Figure (a) shows a schematic of the laser setup; (b) shows actual lasing capsules, which would cost only a few cents to produce. OC = output coupler and FP = Fabry-Perot etalon. Courtesy of Sébastien Sanaur et al./Journal of Applied Physics. Researchers from the Ecole Nationale Supérieure des Mines de Saint-Étienne, the Université Paris and Semilab Semiconductor Physics Laboratory Co. Ltd. in Budapest, Hungary, used a piezoelectric inkjet printing technique to create a gain medium. The commercial ink EMD6415 served as the optical host matrix, exhibiting a refractive index of 1.5 and an absorption coefficient of 0.66 cm-1 at 550 to 680 nm. The ink was mixed with dyes such as Pyrromethene 597 and Rhodamine 640, and then printed in small square shapes onto a quartz slide. These large, 50-mm2 “printed pixels” presented uniform and flat surfaces, with roughness measuring as low as 1.5 nm in different locations of a 50 × 50-μm atomic force microscope scan. This printed, disposable component is referred to as the lasing capsule, and the researchers estimated it could be produced for a few cents. The team used two different types of dyes to produce laser emission ranging from yellow to deep red. Other dyes could cover the blue and green part of the spectrum, they said. The organic laser produced a diffraction-limited output beam with output energy as high as 33.6 μJ with a slope efficiency of 34 percent. Laser emission was shown to be continuously tunable from 570 to 670 nm using an intracavity polymer-based Fabry-Perot etalon. With further development, the researchers said the inkjet-printed laser could send data over short plastic fibers, and serve as a tool for analyzing chemical or biological samples. The research was published in the Journal of Applied Physics (doi: 10.1063/1.49468260).