Rubidium atom spectral lineshapes in high intensity light fields near an optical nanofibre

Abstract

The integration of cold atomic systems with optical nanofibres (ONFs) is an increasingly important experimental platform. Here, we report on the spectra observed during a strongly driven, single-frequency, two-photon excitation of cold rubidium atoms near an ONF. At resonance, two competitive processes, namely a higher excitation rate and stronger pushing of atoms from the nanofibre due to resonance scattering, need to be considered. We discuss the processes that lead to the observed two-peak profile in the fluorescence spectrum as the excitation laser is scanned across the resonance, noting that the presence of the ONF dramatically changes the fluorescence signal. These observations are useful for experiments where high electric field intensities near an ONF are needed, for example when driving nonlinear processes.

Atom-light interactions using optical nanofibres—a perspective

“…Simultaneously, an upconverted 420 nm optical field can be generated with the pumps and signal fields coupled to the guided modes [76]. Note that the nanofibre-based multilevel cascade atomic system allows us to observe two-photon guided-mode coupled excitation of the 5S 1/2 -6S 1/2 transition in 87 Rb [77] and the dependence of the generated fluorescence photons on the input polarisation of the excitation field [78]. In addition, this system enabled the observation of electric quadrupole transitions from 5S 1/2 to 4D 3/2 in laser-cooled 87 Rb atoms using guided-mode light at 516.5 nm [48,79], having potential applications in high precision measurements such as parity non-conservation [80].…”

Using optical nanofibres to mediate cold atom interactions

“…We have performed several experimental and theoretical studies related to ground state and excited state alkali atom interactions with the evanescent light fields of optical nanofibres. These allow us to explore some hardto-access transitions in the alkali atoms, such as quadrupole excitations [3,4], and to determine the influence of the dielectric nanofibre on spectral emissions and lineshapes [5][6][7]. Two specific examples of studies that we have completed are detailed in the following.…”