Efficient fiber-coupled single-photon source based on quantum dots in a photonic-crystal waveguide

Abstract

Many photonic quantum information processing applications would benefit from a high brightness, fiber-coupled source of triggered single photons. Here, we present a fiber-coupled photonic-crystal waveguide single-photon source relying on evanescent coupling of the light field from a tapered out-coupler to an optical fiber. A two-step approach is taken where the performance of the tapered out-coupler is recorded first on an independent device containing an on-chip reflector. Reflection measurements establish that the chip-to-fiber coupling efficiency exceeds 80 %. The detailed characterization of a high-efficiency photonic-crystal waveguide extended with a tapered out-coupling section is then performed. The corresponding overall single-photon source efficiency is 10.9 % ± 2.3 %, which quantifies the success probability to prepare an exciton in the quantum dot, couple it out as a photon in the waveguide, and subsequently transfer it to the fiber. The applied out-coupling method is robust, stable over time, and broadband over several tens of nanometers, which makes it a highly promising pathway to increase the efficiency and reliability of planar chip-based single-photon sources.

Fiber-Coupled Diamond Quantum Nanophotonic Interface

“…As diamond nanophotonics continues to enable advances in other disciplines (including non-linear optics [34,35] and optomechanics [36,37]), the demand for scalable technology necessitates moving beyond isolated devices, to fully integrated on-chip nanophotonic networks in which waveguides route photons between optical cavities [38]. Moreover, for applications involving single photons, such as quantum nonlinear optics with diamond color centers [12,22], efficient off-chip optical coupling schemes are necessary to provide seamless transition of on-chip photons into commercial single mode optical fibers [39][40][41][42].…”

Efficient Pulse‐Excitation Techniques for Single Photon Sources from Quantum Dots in Optical Cavities

“…The increased theoretical understanding of how to realize high SPS figure‐of‐merit as well as experimental advances in charge noise reduction has led to numerous photon sources in recent years with high efficiency, purity (lack of multiphoton events), and quantum indistinguishability of emitted photons . Waveguide‐based photon sources have also seen extensive development, and integrated cavity‐waveguide systems have the potential to harness the advantages of cavity coupling …”

Generation of Non‐Classical Light Using Semiconductor Quantum Dots

“…For on‐chip applications such as integrated quantum photonic circuits, QDs are often integrated into waveguides rather than cavities . Here, photonic crystal W1 waveguides, which consist of one row of missing holes, have been used as well as photonic crystal glide‐plane waveguides, which allow for a chiral light–matter coupling, and nanobeam waveguides . Due to the efficient emission of QDs into the waveguide mode high source brightness in the waveguide can be realized.…”

“…This is quantified by the β‐factor which is the ratio of emission into the desired mode compared to all emission and for QDs in photonic crystal waveguides, β‐factors as high as have been observed . The single photons can then be used on‐chip, for example, for quantum networks or efficiently coupled to single mode fibers . In addition to generating single photons using the schemes discussed above, nonlinear quantum optics can also result in the reflection of a coupled QD–single mode waveguide system to generate single photons through nonlinear quantum optics …”