Tuneable red, green, and blue single-mode lasing in heterogeneously coupled organic spherical microcavities

Tuneable microlasers that span the full visible spectrum, particularly red, green, and blue (RGB) colors, are of crucial importance for various optical devices. However, RGB microlasers usually operate in multimode because the mode selection strategy cannot be applied to the entire visible spectrum simultaneously, which has severely restricted their applications in on-chip optical processing and communication. Here, an approach for the generation of tuneable multicolor single-mode lasers in heterogeneously coupled microresonators composed of distinct spherical microcavities is proposed. With each microcavity serving as both a whispering-gallery-mode (WGM) resonator and a modulator for the other microcavities, a single-mode laser has been achieved. The colors of the single-mode lasers can be freely designed by changing the optical gain in coupled cavities owing to the flexibility of the organic materials. Benefiting from the excellent compatibility, distinct color-emissive microspheres can be integrated to form a heterogeneously coupled system, where tuneable RGB single-mode lasing is realized owing to the capability for optical coupling between multiple resonators. Our findings provide a comprehensive understanding of the lasing modulation that might lead to innovation in structure designs for photonic integration.
Lasers: Generating all colors in a better mode A system for improved control over laser light emission generates any frequency in the visible spectrum, creating what is termed a red, green and blue (RGB) laser, in the advantageous form known as ‘single-mode’ lasing. Most RGB lasers deliver ‘multimode’ signals, in which the light is distributed among several wavelengths around the central most intense and desired wavelength. The preferable single-mode RGB lasing has been developed by researchers in China, led by Yong Sheng Zhao at the Institute of Chemistry of the Chinese Academy of Sciences in Beijing. It uses closely coupled organic (carbon compound-based) microcavities as the regions in which the light is generated and amplified, delivering single frequencies of tunable laser light. This innovation will open new possibilities for using RGB lasing in optical processing and communications systems.