Nano Lett. http://doi.org/gckz6q (2017)

The development of chip-based quantum photonic devices requires the successful integration of single-photon sources with waveguide circuitry. Now, Je-Hyung Kim and co-workers from the USA and the Republic of Korea have developed a pick-and-place technique to transfer a quantum emitter composed of an InP nanobeam containing InAs quantum dots (QDs) directly onto a Si waveguide with nanometre-scale precision. The InP nanobeam (500 nm wide and 280 nm thick) and Si waveguide (400 nm wide and 220 nm thick) were both fabricated by using electron-beam lithography. The nanobeam is tapered at an angle of 6° over a length of 5 μm in order to adiabatically convert the photonic mode into the correct shape for the Si waveguide. The pick-and-place technique relies on the use of a focused ion beam to detach the InP nanobeam from a substrate by cutting tethers. The nanobeam is then picked up by the tip of a microprobe (it adheres to the nanobeam due to the van der Waals force) and a scanning electron microscope is used to image the position of the nanobeam as it placed onto the silicon waveguide. With the use of a y-shaped Si waveguide, the single-photon nature of the InAs QDs emitting around 1,300 nm was confirmed by a Hanbury-Brown and Twiss measurement.

Credit: American Chemical Society