Cavity Enhanced Light Emission from Electrically Driven Carbon Nanotubes

Nanoscale photonic emitters are essential elements for on-chip networks and optical interconnects. Carbon nanotubes (CNTs) can be envisioned as electrically driven waveguide-integrated light sources for future on-chip data... [ view full abstract ]

Nanoscale photonic emitters are essential elements for on-chip networks and optical interconnects. Carbon nanotubes (CNTs) can be envisioned as electrically driven waveguide-integrated light sources for future on-chip data communication due to their unique structural, electrical and optical properties. The challenge thereby is to integrate and electrically contact solution processed CNTs across CMOS compatible waveguide structures and to enforce efficient coupling of light from the CNT into the waveguide. Recently, we realized wafer scale, broadband CNT-based emitters integrated with nanophotonic circuits allowing for propagation of light over centimeter distances [1]. Moreover, we have shown that semiconducting CNTs can act as electroluminescent single photon sources, embedded in fully electrically triggered quantum photonic circuits [2]. Here we demonstrate ultrafast light emitters with exceptionally narrow linewidths based on cavity-coupled CNTs [3].

Hundreds of nanophotonic circuits with integrated CNTs were fabricated using a number of large scale nanostructuring techniques. Electrodes, waveguides and photonic crystal nanobeam cavities were defined by means of electron beam lithography and subsequently formed using metal evaporation, reactive ion and wet etching, respectively. Finally, dielectrophoresis allowed for scalable and site-selective placement of individual CNTs from pre-sorted suspensions into photonic cavities between metal electrodes (Fig. 1).

In combination with a nanobeam cavity CNTs transform into exceptionally narrowline light sources emitting at arbitrary designed wavelength (Fig. 2a). Enhanced emission couples into the underlying photonic network with high reproducibility for both dc and ac biased CNTs. Waveguide-integrated CNTs emerged as high-speed transducers for light pulse generation in the GHz range (Fig. 2b). Our approach holds promise for active photonic networks and localized sensing applications in a chip-scale framework.

[1] S. Khasminskaya, F. Pyatkov et. al., Adv. Mater. 26, 3465–3472 (2014).
[2] S. Khasminskaya, F. Pyatkov et. al., Nat. Photon. 10, 727-732 (2016).
[3] F. Pyatkov, V. Fütterling et. al., Nat. Photon. 10, 420-427 (2016).