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

Fiber-taper collected photoluminescence characterization of diamond microdisks

Tamiko Masuda

Published May 15, 2018• 0 citations
Publisher

Abstract

A key architectural element of future quantum photonic networks is an efficient light-matter interface to connect electronic and photonic qubit systems. Nanophotonic resonators can be fabricated on-chip to provide such interfaces for atomic-like defect centers in diamond, which are leading qubit candidates. Fabrication advancements have recently lead to the construction of high quality diamond microdisk resonators, which show potential to reach enhancements with Purcell factor CNV ∼ 50. Here, a room-temperature experimental apparatus integrating free space and visible wavelength fiber-taper measurement capabilities is built to characterize diamond microdisk resonators. Using this setup, microdisk wisphering gallery modes with quality factors at visible wavelengths resonant with defect centers as high as Q ∼ 1 × 105, are observed for the first time. Spectral filtering effects of the taper on the microdisk are analysed to reveal that coupling to these disks may be limited by phase matching requirements. By thinning these disks it should be possible to improve coupling while lowering mode volumes, as desired to optimize Purcell factors.

DOI
10.11575/prism/31924

Related papers

Fiber-taper collected emission from NV centers in high-Q/V diamond microdisks

Tamiko Masuda, John Patrick Hadden, David P. Lake +3 more

Fiber-coupled microdisks are a promising platform for enhancing the spontaneous emission from color centers in diamond. The measured cavity-enhanced emission from the microdisk is governed by the effective volume ( V ) of each cavity mode, the cavity quality factor ( Q ), and the coupling between the microdisk and the fiber. Here we observe room temperature photoluminescence from an ensemble of nitrogen-vacancy centers into high Q / V microdisk modes, which when combined with coherent spectroscopy of the microdisk modes, allows us to elucidate the relative contributions of these factors. The broad emission spectrum acts as an internal light source facilitating mode identification over several cavity free spectral ranges. Analysis of the fiber taper collected microdisk emission reveals spectral filtering both by the cavity and the fiber taper, the latter of which we find preferentially couples to higher-order microdisk modes. Coherent mode spectroscopy is used to measure Q ∼ 1 × 10 5 – the highest reported values for diamond microcavities operating at visible wavelengths. With realistic optimization of the microdisk dimensions, we predict that Purcell factors of ∼50 are within reach.

arXiv:2310.04487•Optics Express•Dec 4, 2023•12 citations

Adiabatic optical fiber coupling for diamond quantum nanophotonic devices

K. Aoyama, M. Kamata, S. Hachuda +14 more

Efficient and stable interfaces between quantum devices and optical fibers are a key requirement for realizing large-scale quantum networks and distributed quantum computing. Adiabatic coupling between a diamond waveguide and a tapered fiber provides a promising route to broadband, efficient, and robust optical coupling [*]. In this work, we present the design, fabrication, and characterization of such interface. First, we performed FDTD simulations to optimize the diamond nanobeam geometry. These simulations predict a maximum coupling efficiency of 98% with an optimized design. Next, tapered optical fibers with angles <3° and tips <150 nm were fabricated using an optimized hydrofluoric acid etching process. Finally, we experimentally evaluated the coupling efficiency by measuring photoluminescence from nitrogen-vacancy centers in a diamond nanobeam through the fiber, yielding an efficiency of 14%. These results establish a clear design path for a practical interface. The gap between simulation and experiment highlights the need to improve physical contact and nanobeam fabrication. Future work will target these optimizations to realize a more efficient and robust packaged device, a critical component for quantum networks.

•Oct 10, 2025•0 citations

Fiber-Coupled Diamond Micro-Waveguides toward an Efficient Quantum Interface for Spin Defect Centers

Masazumi Fujiwara, Oliver Neitzke, Tim Schröder +8 more

We report the direct integration and efficient coupling of nitrogen vacancy (NV) color centers in diamond nanophotonic structures into a fiber-based photonic architecture at cryogenic temperatures. NV centers are embedded in diamond micro-waveguides (μWGs), which are coupled to fiber tapers. Fiber tapers have low-loss connection to single-mode optical fibers and hence enable efficient integration of NV centers into optical fiber networks. We numerically optimize the parameters of the μWG-fiber-taper devices designed particularly for use in cryogenic experiments, resulting in 35.6% coupling efficiency, and experimentally demonstrate cooling of these devices to the liquid helium temperature of 4.2 K without loss of the fiber transmission. We observe sharp zero-phonon lines in the fluorescence of NV centers through the pigtailed fibers at 100 K. The optimized devices with high photon coupling efficiency and the demonstration of cooling to cryogenic temperatures are an important step to realize fiber-based quantum nanophotonic interfaces using diamond spin defect centers.

ACS Omega•Oct 26, 2017•14 citations

A Vertically Loaded Diamond Microdisk Resonator (VLDMoRt) for Quantum Networks

Yuqin Duan, Kevin C. Chen, Dirk Englund +1 more

We propose and optimize a vertically-loaded diamond microdisk resonator (VLDMoRt) coupled to a nitrogen-vacancy (NV) center in diamond for efficient collection of fluorescence emission into low numerical aperture ($\text{NA}$) free-space modes. The VLDMoRt achieves a Purcell enhancement of 172 with 39\% of the emitted light collected within a $\text{NA}$ of 0.6, leading to a total external spin-photon collection efficiency of 0.33. As the design is compatible with established nanofabrication techniques and couples to low-$\text{NA}$ modes accessible by cryogenic free-space optical systems, it is a promising avenue for increasing the efficiency and scalability of quantum devices based on diamond quantum emitters.

•May 12, 2021•0 citations

Low-temperature tapered-fiber probing of diamond nitrogen-vacancy ensembles coupled to GaP microcavities

Kai‐Mei C. Fu, Paul E. Barclay, Charles Santori +2 more

In this work, we present a platform for testing the device performance of a cavity–emitter system, using an ensemble of emitters and a tapered optical fiber. This method provides high-contrast spectra of the cavity modes, selective detection of emitters coupled to the cavity and an estimate of the device performance in the single-emitter case. Using nitrogen-vacancy (NV) centers in diamond and a GaP optical microcavity, we are able to tune the cavity onto the NV resonance at 10 K, couple the cavity-coupled emission to a tapered fiber and measure the fiber-coupled NV spontaneous emission decay. Theoretically, we show that the fiber-coupled average Purcell factor is 2–3 times greater than that of free-space collection, although due to ensemble averaging it is still a factor of 3 less than the Purcell factor of a single, ideally placed center.

arXiv:1102.5372•New Journal of Physics•May 31, 2011•28 citations

Saturable absorption in defect-rich diamond nanophotonics

Christopher Coutts, Nicholas J. Sorensen, Elham Zohari +3 more

Diamond is a leading quantum photonics platform due to its ability to host qubits based on crystal defects such as nitrogen-vacancy centres. Fabricating nanophotonic devices from defect-rich diamond, which underpins many quantum sensing technologies, promises enhanced performance and integrability of diamond quantum sensors. Here we demonstrate microdisk cavities fabricated from defect-rich diamond that support optical modes with high quality factor (${Q}\sim7\times10^4$ at $1042\,$nm) and show that they exhibit saturable absorption. Power-dependent spectroscopy measurements spanning 979$\,$nm to 1604$\,$nm are used to observe intensity-dependent cavity loss and extract wavelength-dependent absorption coefficients and saturation intensities. At 1047$\,$nm, we observe saturation and measure a saturation intensity of $2.1\,(8)\,$MW/cm$^2$ and an absorption coefficient of $0.53\,(2)\,$cm$^{-1}$. These results provide insight into defect-mediated optical loss in diamond nanophotonics and suggest strategies to harness defect-induced nonlinearities in future diamond photonic devices.

physics.opticsCross-listedarXiv:2603.11367•Optica•Mar 13, 2026•0 citations
A key architectural element of future quantum photonic networks is an efficient light-matter interface to connect electronic and photonic qubit systems. Nanophotonic resonators can be fabricated on-chip to provide such interfaces for atomic-like defect centers in diamond, which are leading qubit candidates. Fabrication advancements have recently lead to the construction of high quality diamond microdisk resonators, which show potential to reach enhancements with Purcell factor CNV ∼ 50. Here, a room-temperature experimental apparatus integrating free space and visible wavelength fiber-taper measurement capabilities is built to characterize diamond microdisk resonators. Using this setup, microdisk wisphering gallery modes with quality factors at visible wavelengths resonant with defect centers as high as Q ∼ 1 × 105, are observed for the first time. Spectral filtering effects of the taper on the microdisk are analysed to reveal that coupling to these disks may be limited by phase matching requirements. By thinning these disks it should be possible to improve coupling while lowering mode volumes, as desired to optimize Purcell factors.
Fiber-coupled microdisks are a promising platform for enhancing the spontaneous emission from color centers in diamond. The measured cavity-enhanced emission from the microdisk is governed by the effective volume ( V ) of each cavity mode, the cavity quality factor ( Q ), and the coupling between the microdisk and the fiber. Here we observe room temperature photoluminescence from an ensemble of nitrogen-vacancy centers into high Q / V microdisk modes, which when combined with coherent spectroscopy of the microdisk modes, allows us to elucidate the relative contributions of these factors. The broad emission spectrum acts as an internal light source facilitating mode identification over several cavity free spectral ranges. Analysis of the fiber taper collected microdisk emission reveals spectral filtering both by the cavity and the fiber taper, the latter of which we find preferentially couples to higher-order microdisk modes. Coherent mode spectroscopy is used to measure Q ∼ 1 × 10 5 – the highest reported values for diamond microcavities operating at visible wavelengths. With realistic optimization of the microdisk dimensions, we predict that Purcell factors of ∼50 are within reach.
Efficient and stable interfaces between quantum devices and optical fibers are a key requirement for realizing large-scale quantum networks and distributed quantum computing. Adiabatic coupling between a diamond waveguide and a tapered fiber provides a promising route to broadband, efficient, and robust optical coupling [*]. In this work, we present the design, fabrication, and characterization of such interface. First, we performed FDTD simulations to optimize the diamond nanobeam geometry. These simulations predict a maximum coupling efficiency of 98% with an optimized design. Next, tapered optical fibers with angles <3° and tips <150 nm were fabricated using an optimized hydrofluoric acid etching process. Finally, we experimentally evaluated the coupling efficiency by measuring photoluminescence from nitrogen-vacancy centers in a diamond nanobeam through the fiber, yielding an efficiency of 14%. These results establish a clear design path for a practical interface. The gap between simulation and experiment highlights the need to improve physical contact and nanobeam fabrication. Future work will target these optimizations to realize a more efficient and robust packaged device, a critical component for quantum networks.
We report the direct integration and efficient coupling of nitrogen vacancy (NV) color centers in diamond nanophotonic structures into a fiber-based photonic architecture at cryogenic temperatures. NV centers are embedded in diamond micro-waveguides (μWGs), which are coupled to fiber tapers. Fiber tapers have low-loss connection to single-mode optical fibers and hence enable efficient integration of NV centers into optical fiber networks. We numerically optimize the parameters of the μWG-fiber-taper devices designed particularly for use in cryogenic experiments, resulting in 35.6% coupling efficiency, and experimentally demonstrate cooling of these devices to the liquid helium temperature of 4.2 K without loss of the fiber transmission. We observe sharp zero-phonon lines in the fluorescence of NV centers through the pigtailed fibers at 100 K. The optimized devices with high photon coupling efficiency and the demonstration of cooling to cryogenic temperatures are an important step to realize fiber-based quantum nanophotonic interfaces using diamond spin defect centers.
We propose and optimize a vertically-loaded diamond microdisk resonator (VLDMoRt) coupled to a nitrogen-vacancy (NV) center in diamond for efficient collection of fluorescence emission into low numerical aperture (NA\text{NA}NA) free-space modes. The VLDMoRt achieves a Purcell enhancement of 172 with 39\% of the emitted light collected within a NA\text{NA}NA of 0.6, leading to a total external spin-photon collection efficiency of 0.33. As the design is compatible with established nanofabrication techniques and couples to low-NA\text{NA}NA modes accessible by cryogenic free-space optical systems, it is a promising avenue for increasing the efficiency and scalability of quantum devices based on diamond quantum emitters.
In this work, we present a platform for testing the device performance of a cavity–emitter system, using an ensemble of emitters and a tapered optical fiber. This method provides high-contrast spectra of the cavity modes, selective detection of emitters coupled to the cavity and an estimate of the device performance in the single-emitter case. Using nitrogen-vacancy (NV) centers in diamond and a GaP optical microcavity, we are able to tune the cavity onto the NV resonance at 10 K, couple the cavity-coupled emission to a tapered fiber and measure the fiber-coupled NV spontaneous emission decay. Theoretically, we show that the fiber-coupled average Purcell factor is 2–3 times greater than that of free-space collection, although due to ensemble averaging it is still a factor of 3 less than the Purcell factor of a single, ideally placed center.
Diamond is a leading quantum photonics platform due to its ability to host qubits based on crystal defects such as nitrogen-vacancy centres. Fabricating nanophotonic devices from defect-rich diamond, which underpins many quantum sensing technologies, promises enhanced performance and integrability of diamond quantum sensors. Here we demonstrate microdisk cavities fabricated from defect-rich diamond that support optical modes with high quality factor (Q∼7×104{Q}\sim7\times10^4Q∼7×104 at 1042 1042\,1042nm) and show that they exhibit saturable absorption. Power-dependent spectroscopy measurements spanning 979 \,nm to 1604 \,nm are used to observe intensity-dependent cavity loss and extract wavelength-dependent absorption coefficients and saturation intensities. At 1047 \,nm, we observe saturation and measure a saturation intensity of 2.1 (8) 2.1\,(8)\,2.1(8)MW/cm2^22 and an absorption coefficient of 0.53 (2) 0.53\,(2)\,0.53(2)cm−1^{-1}−1. These results provide insight into defect-mediated optical loss in diamond nanophotonics and suggest strategies to harness defect-induced nonlinearities in future diamond photonic devices.