Suspended Spot‐Size Converters for Scalable Single‐Photon Devices

Abstract

The realization of a highly efficient optical spot‐size converter for the end‐face coupling of single photons from GaAs‐based nanophotonic waveguides with embedded quantum dots is reported. The converter is realized using an inverted taper and an epoxy polymer overlay providing a 1.3 µm output mode field diameter. The collection of single photons from a quantum dot into a lensed fiber with a rate of 5.84 ± 0.01 MHz is demonstrated and a chip‐to‐fiber coupling efficiency of ≈48% is estimated. The stability and compatibility with cryogenic temperatures make the epoxy waveguides a promising material to realize efficient and scalable interconnects between heterogeneous quantum photonic integrated circuits.

On-chip deterministic operation of quantum dots in dual-mode waveguides for a plug-and-play single-photon source

“…Large Purcell enhancement of the radiative decay rate for overcoming residual decoherence and increasing the source repetition rate can also be achieved through a small modification of the circuit 37 . The modified circuit includes an additional photonic crystal (same parameters as the first one) after the emitter section to form a standing-wave cavity for QD emission in mode C. An obvious next step is to implement direct chip-to-fiber coupling 38 thereby circumventing the loss associated with collection, mode shaping and subsequent fiber coupling. Another opportunity is to scale-up the circuit so that one excitation pulse could be pumping multiple QDs in parallel.…”

Photonic Quantum Technologies

“…-The first implementation of a phase estimation algorithm on a qudit-based photonic platform by encoding two qutrits in a single photon is reported, [11] utilizing the high dimensionality in time and frequency degrees of freedom. -A method to fabricate suspended converters to expand the optical spot size of a single-mode GaAs waveguide is developed, [12] where a highly efficient optical spot-size converter for end-face coupling of single photons is reported. -A novel approach for the non-invasive and instantaneous control of few-level systems through the application of an external pump field to tune the phase between incoming and emitted signal was proposed and investigated.…”

On-chip deterministic operation of quantum dots in dual-mode waveguides for a plug-and-play single-photon source

“…The device will also enable improving the collection efficiency for more advanced excitation schemes relying on dichromatic laser pulses [34], which are typically limited by low-efficiency spectral filters. An obvious next step is to implement direct chip-to-fiber coupling [35] thereby circumventing loss associated with collection, mode shaping and subsequent fiber coupling. Another opportunity is to scale-up the circuit so that one excitation pulse could be pumping multiple QDs in parallel.…”