15 December 2017
UNIST and University of Maryland integrate InAs/InP quantum dot single-photon emitters onto silicon photonic chip
A team led by professor Je-Hyung Kim in the School of Natural Science of South Korea’s Ulsan National Institute of Science and Technology (UNIST) in collaboration with professor Edo Waks and a group of researchers at the University of Maryland in the USA has presented a core technology for quantum photonic devices used in quantum information processing by combining quantum dots for generating light and silicon photonic technologies for manipulating light on a single device (Je-Hyung Kim et al, ‘Hybrid Integration of Solid-State Quantum Emitters on a Silicon Photonic Chip’, Nano Letters, 2017, 17 (12), p7394).
“To build photon-based integrated quantum optical devices, it is necessary to produce as many quantum light sources as possible in a single chip,” says Kim. “We have proposed the basic form of quantum optical devices by producing highly effective quantum light source with quantum dots and creating the pathway to manipulate light with the use of silicon substrates.”
However, as the size of quantum dots decreases, they begin to exhibit discontinuous energy structure, which results in having similar properties to the light emitted by atoms. Although quantum dots have been used successfully as highly efficient single-photon sources, they had difficulty controlling light.
The team has demonstrated the integration of silicon photonic devices with a solid-state single-photon emitter. They used a hybrid approach that combines silicon photonic waveguides with InAs/InP quantum dots that act as efficient sources of single photons at telecom wavelengths spanning the O-band and C-band. Then they removed the quantum dots via a pick-and-place procedure with a microprobe tip combined with a focused ion beam and scanning electron microscope. This technique allowed transferring of tapered InP nanobeams containing InAs quantum dots onto a silicon waveguide with nanometer-scale precision.
Picture: Schematic of integrated InP nanobeam and silicon waveguide.
“This integration opens up the possibility to leverage the highly advanced photonics capabilities developed in silicon to control and route non-classical light from on-demand single-photon sources,” the team notes. “In addition, the fabricated devices operate at telecom wavelengths and can be electrically driven, which are useful for fiber-based quantum communication.”
The quantum optical device developed by the team has successfully transferred the emission from the quantum dots along the silicon photonic circuits with high efficiency. Using this, they have also incorporated an on-chip silicon-photonic beam-splitter to perform a Hanbury-Brown and Twiss measurement.
“Our approach could enable integration of pre-characterized III-V quantum photonic devices into large-scale photonic structures to enable complex devices composed of many emitters and photons,” believes Kim.