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

Physical Review Applied

Spectral Broadening of a Single-Photon Transition in the Evanescent Field of an Exposed-Core Fiber

H.P. Griesser, Christopher Perrella, P. S. Light, Andre Nicholas Luiten

Published May 9, 2019• 3 citations
Publisher

Abstract

In a chip-based waveguide, the confined nature of the optical field and proximity of the waveguide's surface must not be ignored. The short transit time of warm atoms through highly confined light fields can strongly influence the observed atomic absorption spectra. Most theoretical studies have focused on fields with Gaussian intensity profiles, but is that realistic? Here the authors model the transit-time-limited interaction between atomic gas and an exponentially decaying evanescent field, and find spectral lineshapes unlike those for a Gaussian field. These simulations compare well to experiments on Rb vapor and the evanescent guided modes of an exposed-core optical fiber.

DOI
10.1103/physrevapplied.11.054026

Related papers

Spectroscopy of Rb atoms in hollow-core fibers

Aaron D. Slepkov, Amar R. Bhagwat, Vivek Venkataraman +2 more

Recent demonstrations of light-matter interactions with atoms and molecules confined to hollow waveguides offer great promise for ultralow-light-level applications. The use of waveguides allows for tight optical confinement over interaction lengths much greater than what could be achieved in bulk geometries. However, the combination of strong atom-photon interactions and nonuniformity of guided light modes gives rise to spectroscopic features that must be understood in order to take full advantage of the properties of such systems. We use light-induced atomic desorption to generate an optically dense Rb vapor at room temperature inside a hollow-core photonic band-gap fiber. Saturable-absorption spectroscopy and passive slow-light experiments reveal large ac Stark shifts, power broadening, and transit-time broadening, that are present in this system even at nanowatt powers.

Physical Review A•May 18, 2010•62 citations

Investigation of the transit-time broadening in optical nanofiber based spectroscopy

Yun Qi, Wei Jin, Hoi Lut Ho

Optical nanofiber is a widely adopted platform for highly efficient light-matter interaction by virtue of its exposed evanescent field with high light intensity. However, the strongly constrained mode field with the wavelength-scale size makes the light-matter interaction time limited in consideration of the random thermal motion of warm molecules, which results in considerable transit-time dephasing and thus line broadening. Here we report a systematic study of the transit-time effect associated with the optical nanofibers. Both simulation and experiment for nanofibers exposed in acetylene demonstrate the considerable transit-time broadened linewidth in the low-pressure range.

Optics Express•Jan 22, 2020•1 citation

Super-extended nanofiber-guided field for coherent interaction with hot atoms

Ran Finkelstein, Gal Winer, David Zeev Koplovich +8 more

We fabricate an extremely thin optical fiber that supports a super-extended mode with a diameter as large as 13 times the optical wavelength, residing almost entirely outside the fiber and guided over thousands of wavelengths (5 mm), to couple guided light to warm atomic vapor. This unique configuration balances between strong confinement, as evident by saturation powers as low as tens of nW, and long interaction times with the thermal atoms, thereby enabling fast and coherent interactions. We demonstrate narrow coherent resonances (tens of MHz) of electromagnetically induced transparency for signals at the single-photon level and long relaxation times (10 ns) of atoms excited by the guided mode. The dimensions of the guided mode’s evanescent field are compatible with the Rydberg blockade mechanism, making this platform particularly suitable for observing quantum nonlinear optics phenomena.

arXiv:2010.08935•Optica•Jan 6, 2021•16 citations

Surface-Induced Spectral Broadening during Efficient Two-Photon Excitation of Cold $^{133}\text{Cs}$ Atoms near an Optical Nanofiber

Yuan Jiang, Xiaodong Qi, Nicolás Vera Paz +5 more

We report the experimental observation of the $^{\text{133}}$Cs 6S$_{\text{1/2}}$ to 6D$_{\text{5/2}}$ single-frequency two-photon transition at low excitation power using an optical nanofiber embedded in a cold atom cloud. We investigate the 917 nm fluorescence spectra modified by the surface-induced interaction of the nanofiber, which exhibits a pronounced asymmetric broadening with a distinct red-shifted tail. We present a systematic theoretical description of the two-photon transition process of atoms near a nanofiber surface, considering atomic angular momentum coupling, guided-mode decay rate, and surface-induced van der Waals interactions. Owing to the tight spatial confinement provided by the guided evanescent field, efficient nonlinear excitation is realized at excitation powers down to tens of microwatts, corresponding to a reduction of approximately four orders of magnitude relative to typical free-space implementations. Our work reveals the interplay among waveguide-modified radiative dynamics, surface-induced interactions, and the spatial distribution of atoms around the nanofiber, and provides insights into further studies on nonlinear optical transitions and surface-mediated atomic dynamics in waveguide quantum electrodynamics systems.

arXiv:2609.38062•Sep 29, 2026•0 citations

Interaction of nanofiber-guided light with a warm atomic vapor

Daniel E. Jones

Systems allowing controllable photon-atom interactions are becoming increasingly important for quantum communication applications. One promising platform involves the interaction of the tightly-confined evanescent mode of an optical nanofiber with surrounding atoms. This dissertation will overview our work on the interaction of nanofiber-guided light with a warm rubidium vapor. In comparison to related work with cold atom clouds or trapped atoms, the "warm atom-nanofiber" system is fairly robust but operates in a regime where motional effects of the atoms are significant. We will first discuss a detailed study of saturated absorption in this system, with an emphasis on the role of motional effects in hyperfine pumping rates and various line broadening mechanisms. The power needed to saturate the system is essentially a measure of the system?s capability to enable nonlinear optical interactions of the kind that are needed for quantum communication applications, and we observe remarkably ultralow saturation powers of 10?s of nW (corresponding to only ?10 photons passing through the nanofiber at a given time). We then utilize this strong nonlinearity to demonstrate 3-level ladder-type electromagnetically induced transparency (EIT) and all-optical modulation with ultralow control-field powers on the order of only a few ?W. Finally, we discuss a novel nanofiber-segment nonlinear ring resonator comprised of a large loop of conventional single-mode fiber with a short nanofiber segment surrounded by a warm rubidium vapor. In this device, the cavity enhanced evanescent field of the nanofiber enables even stronger photon-atom interactions.

•Jan 1, 2016•0 citations

Atomic vapor spectroscopy in integrated photonic structures

Ralf Ritter, Nico Gruhler, Wolfram H. P. Pernice +3 more

We investigate an integrated optical chip immersed in atomic vapor providing several waveguide geometries for spectroscopy applications. The narrow-band transmission through a silicon nitride waveguide and interferometer is altered when the guided light is coupled to a vapor of rubidium atoms via the evanescent tail of the waveguide mode. We use grating couplers to couple between the waveguide mode and the radiating wave, which allow for addressing arbitrary coupling positions on the chip surface. The evanescent atom-light interaction can be numerically simulated and shows excellent agreement with our experimental data. This work demonstrates a next step towards miniaturization and integration of alkali atom spectroscopy and provides a platform for further fundamental studies of complex waveguide structures.

Applied Physics Letters•Jul 27, 2015•64 citations
In a chip-based waveguide, the confined nature of the optical field and proximity of the waveguide's surface must not be ignored. The short transit time of warm atoms through highly confined light fields can strongly influence the observed atomic absorption spectra. Most theoretical studies have focused on fields with Gaussian intensity profiles, but is that realistic? Here the authors model the transit-time-limited interaction between atomic gas and an exponentially decaying evanescent field, and find spectral lineshapes unlike those for a Gaussian field. These simulations compare well to experiments on Rb vapor and the evanescent guided modes of an exposed-core optical fiber.
Recent demonstrations of light-matter interactions with atoms and molecules confined to hollow waveguides offer great promise for ultralow-light-level applications. The use of waveguides allows for tight optical confinement over interaction lengths much greater than what could be achieved in bulk geometries. However, the combination of strong atom-photon interactions and nonuniformity of guided light modes gives rise to spectroscopic features that must be understood in order to take full advantage of the properties of such systems. We use light-induced atomic desorption to generate an optically dense Rb vapor at room temperature inside a hollow-core photonic band-gap fiber. Saturable-absorption spectroscopy and passive slow-light experiments reveal large ac Stark shifts, power broadening, and transit-time broadening, that are present in this system even at nanowatt powers.
Optical nanofiber is a widely adopted platform for highly efficient light-matter interaction by virtue of its exposed evanescent field with high light intensity. However, the strongly constrained mode field with the wavelength-scale size makes the light-matter interaction time limited in consideration of the random thermal motion of warm molecules, which results in considerable transit-time dephasing and thus line broadening. Here we report a systematic study of the transit-time effect associated with the optical nanofibers. Both simulation and experiment for nanofibers exposed in acetylene demonstrate the considerable transit-time broadened linewidth in the low-pressure range.
We fabricate an extremely thin optical fiber that supports a super-extended mode with a diameter as large as 13 times the optical wavelength, residing almost entirely outside the fiber and guided over thousands of wavelengths (5 mm), to couple guided light to warm atomic vapor. This unique configuration balances between strong confinement, as evident by saturation powers as low as tens of nW, and long interaction times with the thermal atoms, thereby enabling fast and coherent interactions. We demonstrate narrow coherent resonances (tens of MHz) of electromagnetically induced transparency for signals at the single-photon level and long relaxation times (10 ns) of atoms excited by the guided mode. The dimensions of the guided mode’s evanescent field are compatible with the Rydberg blockade mechanism, making this platform particularly suitable for observing quantum nonlinear optics phenomena.
Surface-Induced Spectral Broadening during Efficient Two-Photon Excitation of Cold 133Cs^{133}\text{Cs}133Cs Atoms near an Optical Nanofiber
We report the experimental observation of the 133^{\text{133}}133Cs 6S1/2_{\text{1/2}}1/2​ to 6D5/2_{\text{5/2}}5/2​ single-frequency two-photon transition at low excitation power using an optical nanofiber embedded in a cold atom cloud. We investigate the 917 nm fluorescence spectra modified by the surface-induced interaction of the nanofiber, which exhibits a pronounced asymmetric broadening with a distinct red-shifted tail. We present a systematic theoretical description of the two-photon transition process of atoms near a nanofiber surface, considering atomic angular momentum coupling, guided-mode decay rate, and surface-induced van der Waals interactions. Owing to the tight spatial confinement provided by the guided evanescent field, efficient nonlinear excitation is realized at excitation powers down to tens of microwatts, corresponding to a reduction of approximately four orders of magnitude relative to typical free-space implementations. Our work reveals the interplay among waveguide-modified radiative dynamics, surface-induced interactions, and the spatial distribution of atoms around the nanofiber, and provides insights into further studies on nonlinear optical transitions and surface-mediated atomic dynamics in waveguide quantum electrodynamics systems.
Systems allowing controllable photon-atom interactions are becoming increasingly important for quantum communication applications. One promising platform involves the interaction of the tightly-confined evanescent mode of an optical nanofiber with surrounding atoms. This dissertation will overview our work on the interaction of nanofiber-guided light with a warm rubidium vapor. In comparison to related work with cold atom clouds or trapped atoms, the "warm atom-nanofiber" system is fairly robust but operates in a regime where motional effects of the atoms are significant. We will first discuss a detailed study of saturated absorption in this system, with an emphasis on the role of motional effects in hyperfine pumping rates and various line broadening mechanisms. The power needed to saturate the system is essentially a measure of the system?s capability to enable nonlinear optical interactions of the kind that are needed for quantum communication applications, and we observe remarkably ultralow saturation powers of 10?s of nW (corresponding to only ?10 photons passing through the nanofiber at a given time). We then utilize this strong nonlinearity to demonstrate 3-level ladder-type electromagnetically induced transparency (EIT) and all-optical modulation with ultralow control-field powers on the order of only a few ?W. Finally, we discuss a novel nanofiber-segment nonlinear ring resonator comprised of a large loop of conventional single-mode fiber with a short nanofiber segment surrounded by a warm rubidium vapor. In this device, the cavity enhanced evanescent field of the nanofiber enables even stronger photon-atom interactions.
We investigate an integrated optical chip immersed in atomic vapor providing several waveguide geometries for spectroscopy applications. The narrow-band transmission through a silicon nitride waveguide and interferometer is altered when the guided light is coupled to a vapor of rubidium atoms via the evanescent tail of the waveguide mode. We use grating couplers to couple between the waveguide mode and the radiating wave, which allow for addressing arbitrary coupling positions on the chip surface. The evanescent atom-light interaction can be numerically simulated and shows excellent agreement with our experimental data. This work demonstrates a next step towards miniaturization and integration of alkali atom spectroscopy and provides a platform for further fundamental studies of complex waveguide structures.