High-quality factor, biological microsphere and microhemisphere lasers fabricated by a single solution process

Whispering gallery mode (WGM) biological microlasers are attractive building blocks for developing biodegradable and implantable optical devices. To date, various biomaterials, laser configurations, and fabrication techniques have been investigated for WGM biolasers. However, the current technology is time-consuming and generally is not possible for fabricating various laser configurations in a single process. In this work, we demonstrate a unique technique that can produce micrometer-sized biolasers with two different geometries, microspheres and microhemispheres, in a short time of about 10 min. Using this technique, spheres and hemispheres with diameter from 20-100μm can be fabricated easily from a dye-doped bovine serin albumin solution. The fabricated spheres and hemispheres can act as excellent lasers under optical pumping. The lasing threshold of the microsphere lasers is about 10 μJ/mm2 and their quality (Q) factor varies with size which can reach 3000 for a 90μm-diameter sphere. The hemisphere lasers exhibit a slightly higher lasing threshold and lower Q factor. © 2020 Elsevier B.V.