Optical waveguide beam splitters based on hybrid metal–dielectric–semiconductor nanostructures

• A hybrid metal–dielectric–semiconductor nanostructure correlating the metal nanodisks and semiconductor nanoribbon is proposed.
• The nanostructure is fabricated through CVD and EBL technique.
• The measurement is realized by combing AFM with the defocused imaging technique which is realized in a normal wide-field fluorescence microscope.
• The beam splitting mechanism of this nanostructure is investigated by numerical simulation.
• The beam splitting mechanism reveals that this hybrid metal–dielectric–semiconductor nanostructure can be applied as optical waveguide beam splitter.

Miniature integration is desirable for the future photonics circuit. Low-dimensional semiconductor and metal nanostructures is the potential building blocks in compact photonic circuits for their unique electronic and optical properties. In this work, a hybrid metal–dielectric–semiconductor nanostructure is designed and fabricated to realizing a nano-scale optical waveguide beam splitter, which is constructed with the sandwiched structure of a single CdS nanoribbon/HfO2 thin film/Au nanodisk arrays. Micro-optical investigations reveal that the guided light outputting at the terminal end of the CdS ribbon is well separated into several light spots. Numerical simulations further demonstrate that the beam splitting mechanism is attributed to the strong electromagnetic coupling between the Au nanodisks and light guided in the nanoribbon. The number of the split beams (light spots) at the terminal end of the nanoribbon is mainly determined by the number of the Au nanodisk rows, as well as the distance of the blank region between the nanodisks array and the end of the CdS ribbon, owing to the interference between the split beams. These optical beam splitters may find potential applications in high-density integrated photonic circuits and systems.