A University of Tokyo research group led by Associate Professor Yuichiro Kato at the Graduate School of Engineering and Professor Yasuhiko Arakawa at the Institute of Industrial Science succeeded in achieving optical coupling efficiency of over 85% for individual carbon nanotube emitters coupled to photonic crystal structures.
Single-walled carbon nanotubes are known to be bright emitters in the telecommunication wavelength that can be grown directly on silicon, making them attractive for applications in nanoscale photonic devices. In particular, air-suspended carbon nanotubes show excellent emission properties, but efficiency of their optical coupling to photonic structures has remained low.
The research group has drastically improved the coupling efficiency by utilizing a specially designed photonic crystal structure. In contrast to conventional structures which confine light within the silicon material, the new design allows light from carbon nanotubes to fill air holes, enhancing the optical interaction with air-suspended carbon nanotubes and greatly increasing the propagation of light into the optical resonator. This technique may see applications in nanoscale photonic devices such as lasers using atomic layer materials and are an important step towards miniaturization of optical circuits and development of nanoscale photonic devices with new functionalities.
Source: University of Tokyo