Simultaneous ultraviolet, visible, and near-infrared continuous-wave lasing in a rare-earth-doped microcavity

Bo Jiang; Song Zhu; Linhao Ren; Lei Shi; Xinliang Zhang

doi:10.1117/1.AP.4.4.046003

Abstract

Microlaser with multiple lasing bands is critical in various applications, such as full-color display, optical communications, and computing. Here, we propose a simple and efficient method for homogeneously doping rare earth elements into a silica whispering-gallery microcavity. By this method, an Er-Yb co-doped silica microsphere cavity with the highest quality (Q) factor (exceeding 10⁸) among the rare-earth-doped microcavities is fabricated to demonstrate simultaneous and stable lasing covering ultraviolet, visible, and near-infrared bands under room temperature and a continuous-wave pump. The thresholds of all the lasing bands are estimated to be at the submilliwatt level, where both the ultraviolet and violet continuous wave upconversion lasing from rare earth elements has not been separately demonstrated under room temperature until this work. This ultrahigh-Q doped microcavity is an excellent platform for high-performance multiband microlasers, ultrahigh-precision sensors, optical memories, and cavity-enhanced light–matter interaction studies.

Multiband lasers are attractive for their potential applications in color display, lighting, wavelength-division multiplexing, optical communications, and computing.1^–4 Rare earth (RE) elements with abundant long-lived intermediate energy levels and intraconfigurational transitions can emit light from the deep-ultraviolet to mid-infrared by pumping high-energy or low-energy photons, i.e., downshifting or upconversion, respectively, and thus can be applied in data storage,5^,6 three-dimensional display,7^,8 luminescent biomarkers,9^–11 and lasers.12^,13 Whispering-gallery-mode (WGM) optical microcavities with an ultrahigh quality ( $Q$ ) factor and small mode volume exhibiting ultrahigh energy density and strong light–matter interaction can be applied in sensing,14^–16 nonlinear optics,17^–22 cavity optomechanics,23^,24 and lasers.25^–33 Therefore, doping RE elements into an ultrahigh- $Q$ microcavity without degrading its intrinsic $Q$ factor is an effective way to construct a low-threshold and narrow-linewidth multiband microlaser.