Atomic spectroscopy relies on photons to probe the energy states of atoms, typically in a gas state. In addition to
providing fundamental scientific information, this technique can be applied to a number of photonic devices including
atomic clocks, laser stabilization references, slow light elements, and eventually quantum communications components.
Atomic spectroscopy has classically been done using bulk optics and evacuated transparent vapor cells. Recently, a
number of methods have been introduced to dramatically decrease the size of atomic spectroscopy systems by
integrating optical functionality. We review three of these techniques including: 1) photonic crystal fiber based
experiments, 2) wafer bonded mini-cells containing atomic vapors and integrated with lasers and detectors, and 3)
hollow waveguides containing atomic vapors fabricated on silicon substrates. In the context of silicon photonics, we
will emphasize the hollow waveguide platform. At the heart of these devices is the anti-resonant reflecting optical
waveguide (ARROW). ARROW fabrication techniques will be described for both hollow and solid core designs.
Solid-core waveguides are necessary to direct light on and off the silicon chip while confining atomic vapors to hollow-core
waveguides. We will also discuss the methods and challenges of attaching rubidium vapor reservoirs to the chip.
Experimental results for optical spectroscopy of rubidium atoms on a chip will be presented.
We have recently reported atomic spectroscopy using on-chip rubidium vapor cells based on hollow core waveguides.
To make the cells more robust and capable of multiple temperature cycles, we examined several techniques for Rb
introduction and sealing. To date the most successful sealing technique has been pinching off the end of a short length
of copper tubing. This technique not only hermetically seals the cells, but also allows them to be evacuated to a desired
pressure. We have been able to evacuate glass prototype Rb vapor cells to a pressure as low as 80 mTorr and as high as
2 Torr and successfully observe the Rb optical absorption spectrum. Along with our testing of sealing techniques we
have been observing the effects of different epoxies and inert gas atmospheres on the robustness of vapor cells. With
optimal parameters we have successfully observed the Rb optical absorption spectrum through multiple temperature
cycles. These new Rb introduction and sealing methods will be applied to on-chip cells containing integrated hollow
waveguides which can be used for a number of different optical applications, such as electromagnetically induced
transparency, single-photon nonlinearities, and slow light.
Harnessing the unique optical quantum interference effects associated with electromagnetically induced transparency
(EIT) on a chip promises new opportunities for linear and nonlinear optical devices. Here, we review the status of
integrated atomic spectroscopy chips that could replace conventional rubidium spectroscopy cells. Both linear and
nonlinear absorption spectroscopy with excellent performance are demonstrated on a chip using a self-contained Rb
reservoir and exhibiting a footprint of only 1.5cm x 1cm. In addition, quantum interference effects including V-scheme
and Λ-scheme EIT are observed in miniaturized rubidium glass cells whose fabrication is compatible with on-chip
We review the current status of integrating optical quantum interference effects such as electromagnetically induced
transparency (EIT), slow light, and highly efficient nonlinear processes on a semiconductor chip. A necessary
prerequisite for combining effects such as slow light and related phenomena with the convenience of integrated optics is
the development of integrated alkali vapor cells. Here, we describe the development of integrated rubidium cells based
on hollow-core antiresonant reflecting optical waveguides (ARROWs). Hollow-core waveguides were fabricated on a
silicon platform using conventional microfabrication and filled with rubidium vapor using different methods. Rubidium
absorption through the waveguides was successfully observed which opens the way to integrated atomic and molecular
on a chip. The realization of quantum coherence effects requires additional surface treatment of the waveguide walls,
and the effects of the surface coating on the waveguide properties are presented.