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MN2S : Internship M2 "Sorting of bioelements using a functionalized microbubbles network"
TF : 6-month Master 2 Internship + PhD thesis Two-photon Rb microcell optical clock
Context : The convergence of atomic spectroscopy, MEMS technologies and integrated photonics has allowed the development of high-precision chip-scale atomic devices [1]. Among these instruments, miniaturized atomic clocks with unrivaled sizepower-frequency instability budget (16 cm3, 120 mW, 1 μs/day) have been demonstrated and are now widely deployed in navigation systems, instrumentation, metrology, and communications. However, these microwave chip-scale atomic clocks (CSACs), based on the interaction of hot alkali atoms (Cs or Rb) confined in a micro-fabricated cell with an opticallycarried microwave signal, suffer from limitations and approach their ultimate performances.
In response, last years have seen the emergence of new-generation chip-scale optical atomic clocks [2-3]. In a miniaturized optical frequency reference, the frequency of a narrow-linewidth laser is stabilized onto a narrow optical atomic resonance
detected in a microfabricated alkali vapor cell.
In this domain, we work at FEMTO-ST on the development of a microcell optical clock based on two-photon transition of the Rb atom at 778 nm. In this system, atoms in a MEMS cell are excited by two counter-propagating light fields provided by a single laser at 778 nm. Atoms are then promoted to an excited state from which they spontaneously decay. During their radiative cascade, atoms emit blue fluorescence photons at 420 nm that are detected by a photomultiplier. The latter delivers the narrow atomic response used to lock the frequency of the laser.
Profile: The candidate should appreciate applied physics, for working in a highly-interdisciplinary subject. The candidate should have competences with optics, electronics, mechanics, coding and instrumentation (Python preferred) and be attracted by high-precision metrology. Some knowledge with atomic physics, but also with clean-room techniques, is a clear plus-value.
Subject : The M2 internship and following PhD thesis aim to overcome the above-mentioned limitations. For points 1/ and 2/, the candidate will contribute to the design (mechanical and optical), simulation (thermal/magnetic), development and
characterization of an original microcell physics package for Rb two-photon spectroscopy at 778 nm. Studies will rely on a novel microcell design under-progress at FEMTO-ST. The physics package will embed the microfabricated cell, several
optical components to ensure the generation of the retro-reflected beam (for stimulation of the two-photon transition), and the photomultiplier to detect the blue photons. All this will be configured in an optimal way such that the atomic signal
response will be as high as possible.