As an interdisciplinary research frontier of photonics and nano technology, nanolasers with device size on (sub)wavelength scale show great potential in a variety of scientific and technological areas. With the growing demand for information density and accuracy in highly integrated photonic devices, the nanoscale coherent light source capable of achieving broadband output and good spectral purity is urgently needed.

Until now, multicolor laser usually operated in multimode due to the lack of mode selection effect that is simultaneously applicable to multiple wavebands. The multimode competing would lead to temporal fluctuations and false signaling, which has severely limited their practical implementation in various photonic devices.

Recently, a research group led by Prof. ZHAO Yongsheng at Institute of Chemistry of Chinese Academy of Sciences reported that the dual-color single-mode laser can be realized in axially coupled heterogeneous nanowire resonators. This work was published on Science Advances.

Researchers first fabricated two organic nanowires from different gain materials through liquid self-assembled, and then constructed axially coupled heterogeneous resonators through integrating the two pre-prepared organic nanowires by micromanipulation. In the composite resonator system, each nanowire acts as the laser source and the mode filter simultaneously, mutual mode selection effect can be demonstrated experimentally and theoretically, which enabled the dual-color single-mode laser.

As the gain amplification at different wavelengths are spatially separated from each other, the coupled heterogeneous structure provided three nanoscale output ports for delivering coherent signals with different wavelengths, which could greatly increase the integration level of the functional photonic devices.

The study gave a comprehensive understanding of the connection between photonic functions and nanoarchitectonics, and provided unique insights on the optimal design of organic composite nanomaterials for the desired functionalities.

This work was financially supported by Chinese Academy of Sciences, National Natural Science Foundation of China, and Ministry of Science and Technology of China.