Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2603.09679 · Optics Express

Narrowband heralded single photons via Bragg grating inscription in germanium-doped photonic crystal fiber

Will A. M. Smith, Alex I. Flint, Rex H. S. Bannerman, James C. Gates, Peter G. R. Smith, Alex O. C. Davis, Peter J. Mosley

quant-phSubmitted Mar 10, 2026• Announced Mar 11, 2026• 0 citations
arXivHTMLPDF

Abstract

We present a fiber-based source of narrowband heralded single photons in the telecoms C-band. Photon pairs were generated by spontaneous four-wave mixing in photonic crystal fiber (PCF) with a germanium-doped region incorporated into its core for enhanced photosensitivity. A fiber Bragg grating (FBG) with a bandwidth of 0.2 nm and contrast of 17.5 dB was UV-written into the PCF to reflect a sub-nanometre slice of the photon-pair spectrum. This allowed narrowband photons to be heralded at the proximal end of the fiber by detection events after the distal end. We present photon counting data with a coincidence-to-accidental ratio of up to 70. Our source demonstrates a viable route to fiber-integrated narrowband heralded single photon sources suitable for coupling to quantum memories and interfacing heterogeneous qubit types.

DOI
10.1364/OE.599359

Related papers

Narrowband high-fidelity all-fibre source of heralded single photons at 1570 nm

Alex R. McMillan, Jérémie Fulconis, M. Halder +3 more

An all-fibre heralded single photon source operating at 1570 nm has been demonstrated. The device generates correlated photon pairs, widely spaced in frequency, through four-wave mixing in a photonic crystal fibre. Separation of the pair photons and narrowband filtering is all achieved in fibre. The output heralded single photon rate was 9.2 x 10(4) per second, with a counts-to-accidentals ratio of 10.4 and a heralding fidelity of 52 %. Furthermore, narrowband filtering ensured that the output single photon state was near time-bandwidth limited with a coherence length of 4 ps. Such a source is well suited to quantum information processing applications.

Optics Express•Apr 1, 2009•66 citations

Tunable frequency conversion in doped photonic crystal fiber pumped near degeneracy

Leah R. Murphy, Mateusz J. Olszewski, Petros Androvitsaneas +5 more

Future quantum networks will rely on the ability to coherently transfer optically encoded quantum information between different wavelength bands. Bragg-scattering four-wave mixing in optical fiber is a promising route to achieving this, but requires fibers with precise dispersion control and broadband transmission at signal, target, and pump wavelengths. Here, we introduce a photonic crystal fiber with a germanium-doped core featuring group velocity matching at 1550 nm, the telecoms C-band, and 920 nm, within the emission range of efficient single photon sources based on InAs quantum dots. With low chromatic walk-off and good optical guidance even at long wavelengths, large lengths of this fiber are used to achieve nanometer-scale frequency shifts between wavelengths around 920 nm with up to 79.4% internal conversion efficiency, allowing dissimilar InAs dots to be interfaced. We also show how cascading this frequency conversion can be used to generate a frequency comb away from telecoms wavelengths. Finally, we use the fiber to demonstrate tunable frequency conversion of weak classical signals around 918 nm to the telecoms C-band.

arXiv:2407.09266•Optica•Oct 9, 2024•8 citations

Bridging visible and telecom wavelengths with a single-mode broadband photon pair source

Christoph Söller, Benjamin Brecht, Peter J. Mosley +5 more

We present a spectrally decorrelated photon pair source bridging the visible and telecom wavelength regions. Tailored design and fabrication of a solid-core photonic crystal fiber (PCF) lead to the emission of signal and idler photons into only a single spectral and spatial mode. Thus no narrowband filtering is necessary and the heralded generation of pure photon number states in ultrafast wave packets at telecom wavelengths becomes possible.

arXiv:0908.2932•Physical Review A•Mar 10, 2010•81 citations

Fiber-based narrow-band single-photon source with high heralding efficiency

Lei Yang, Xiaoxin Ma, Cui Liang +2 more

According to the correlated photon pairs produced by spontaneous four-wave mixing in dispersion-shifted fiber, we present a telecom-band single-photon source by using mode-locked laser. Single-photons with a -3 dB bandwidth of 1.1 nm are heralded with more than 50% probability. The measured second-order correlation g(2)(0) is equal to 0.090.01. Our source is well suit for quantum communication systems.

Acta Physica Sinica•Jan 1, 2011•0 citations

Full characterization of an all fiber source of heralded single photons

Yunxiao Zhang, Liang Cui, Xueshi Guo +3 more

We demonstrate a heralded single photon source which is based on the photon pairs generated from pulse pumped spontaneous four wave mixing in a piece of commercially available dispersion shifted fiber. The single photon source at 1550 nm telecom band is characterized with both photon counting technique and homodyne detection method. The heralding efficiency and mode purity can be measured by photon counting while the vacuum contribution part can be found by homodyne detection.

arXiv:2409.14310•Sep 22, 2024•2 citations

FBGs in PCF for Four-Wave Mixing Sources for Quantum Optics

Alex I. Flint, Will A. M. Smith, Alex O. C. Davis +6 more

Photonic crystal fibers (PCFs) offer a high degree of design flexibility, particularly in terms of dispersion control, making them ideal for nonlinear optical processes. These fibers have found applications in various photonic fields, including fiber lasers [1] and single-photon generation [2]. Dispersion control allows for efficient four-wave mixing at desired wavelengths, which can be used in quantum optical sources. These processes require or are enhanced by the use of fiber Bragg gratings (FBGs) in the fiber. For example, in PCF-based FWM heralded single photon sources, FBGs can be used to filter out unwanted noise contributions, such as Raman noise. However, current filtering methods are lossy [3], making it desirable to integrate filters into the fibers themselves. Additionally, specially designed PCFs with FBGs can be used for in-fiber OPOs to generate squeezed light.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 26, 2023•0 citations
We present a fiber-based source of narrowband heralded single photons in the telecoms C-band. Photon pairs were generated by spontaneous four-wave mixing in photonic crystal fiber (PCF) with a germanium-doped region incorporated into its core for enhanced photosensitivity. A fiber Bragg grating (FBG) with a bandwidth of 0.2 nm and contrast of 17.5 dB was UV-written into the PCF to reflect a sub-nanometre slice of the photon-pair spectrum. This allowed narrowband photons to be heralded at the proximal end of the fiber by detection events after the distal end. We present photon counting data with a coincidence-to-accidental ratio of up to 70. Our source demonstrates a viable route to fiber-integrated narrowband heralded single photon sources suitable for coupling to quantum memories and interfacing heterogeneous qubit types.
An all-fibre heralded single photon source operating at 1570 nm has been demonstrated. The device generates correlated photon pairs, widely spaced in frequency, through four-wave mixing in a photonic crystal fibre. Separation of the pair photons and narrowband filtering is all achieved in fibre. The output heralded single photon rate was 9.2 x 10(4) per second, with a counts-to-accidentals ratio of 10.4 and a heralding fidelity of 52 %. Furthermore, narrowband filtering ensured that the output single photon state was near time-bandwidth limited with a coherence length of 4 ps. Such a source is well suited to quantum information processing applications.
Future quantum networks will rely on the ability to coherently transfer optically encoded quantum information between different wavelength bands. Bragg-scattering four-wave mixing in optical fiber is a promising route to achieving this, but requires fibers with precise dispersion control and broadband transmission at signal, target, and pump wavelengths. Here, we introduce a photonic crystal fiber with a germanium-doped core featuring group velocity matching at 1550 nm, the telecoms C-band, and 920 nm, within the emission range of efficient single photon sources based on InAs quantum dots. With low chromatic walk-off and good optical guidance even at long wavelengths, large lengths of this fiber are used to achieve nanometer-scale frequency shifts between wavelengths around 920 nm with up to 79.4% internal conversion efficiency, allowing dissimilar InAs dots to be interfaced. We also show how cascading this frequency conversion can be used to generate a frequency comb away from telecoms wavelengths. Finally, we use the fiber to demonstrate tunable frequency conversion of weak classical signals around 918 nm to the telecoms C-band.
Photonic crystal fibers (PCFs) offer a high degree of design flexibility, particularly in terms of dispersion control, making them ideal for nonlinear optical processes. These fibers have found applications in various photonic fields, including fiber lasers [1] and single-photon generation [2]. Dispersion control allows for efficient four-wave mixing at desired wavelengths, which can be used in quantum optical sources. These processes require or are enhanced by the use of fiber Bragg gratings (FBGs) in the fiber. For example, in PCF-based FWM heralded single photon sources, FBGs can be used to filter out unwanted noise contributions, such as Raman noise. However, current filtering methods are lossy [3], making it desirable to integrate filters into the fibers themselves. Additionally, specially designed PCFs with FBGs can be used for in-fiber OPOs to generate squeezed light.