title: Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications.
abstract: This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm.
authors.affiliation: Micro-Nano Sciences &Systems department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Ravinder
authors.initials: R
authors.lastname: Chutani
authors.affiliation: Micro-Nano Sciences &Systems department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Maurice
authors.affiliation: Micro-Nano Sciences &Systems department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Passilly
authors.affiliation: Micro-Nano Sciences &Systems department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Gorecki
authors.affiliation: Time &Frequency department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Boudot
authors.affiliation: Time &Frequency department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Moustafa
authors.initials: M
authors.lastname: Abdel Hafiz
authors.affiliation: Time &Frequency department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Abbé
authors.affiliation: Time &Frequency department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Galliou
authors.affiliation: Micro-Nano Sciences &Systems department, FEMTO-ST Institute, UMR 6174 CNRS and Université de Franche-Comté, Besançon, France.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Rauch
authors.affiliation: LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, Paris, France.
authors.forename: Emeric
authors.initials: E
authors.lastname: de Clercq