Ultralow-threshold neodymium-doped microsphere lasers on a silicon chip

We demonstrate ultralow-threshold neodymium-doped silica microsphere lasers on a silicon chip with lasing wavelengths of similar to 900 nm and similar to 1060 nm. Neodymium-doped microsphere cavities are fabricated with a series of doping concentrations using silica sol-gel films. Experimentally, we observe single-mode lasing emissions from the high-Q microsphere cavities with a threshold of as low as 1.2 mu W. (C) 2016 Elsevier B.V. All rights reserved.