Atom-Photon Interactions in Atomic Cladded Waveguides: Bridging Atomic and Telecom Technologies

Accurate and stable frequency sources can be realized by locking lasers to well-known transitions between energy levels in isolated quantum systems such as alkali atoms. Unfortunately, current implementations of such frequency standards typically involve bulky optical setups and discrete optical components. Furthermore, the common transitions of alkali atoms are in the near-infrared, hindering their use as frequency references in the telecom regime. Our current work is focused on mitigating these deficiencies. In particular, we demonstrate the design, fabrication, and experimental characterization of an on-chip telecom frequency reference that is based on a ladder transition of rubidium atoms integrated with nanoscale optical waveguides. These atomic cladded waveguides are implemented in a serpentine geometry in order to optimize the chip area and maximize the interaction of light with the alkali atoms. Following its fabrication, the device is used to stabilize a telecom laser around a 1.5 μm wavelength to a precision better than 200 kHz at ∼250 s. Moreover, in spite of the fact that the natural lifetime of the excited state of the atom corresponding to only a few megahertz line widths, the nanoscale confinement of the optical mode dictates ultrashort interaction times and extreme photonic energy densities allowing us to demonstrate low power and faster (∼200 MHz) all-optical modulation of a near-infrared light with a telecom light. The results presented in this paper push forward the efforts toward fully integrated chip-scale stabilization system and provide an extremely efficient link between atomic based devices and silicon photonics platform in the telecom.