Atomic Spectroscopy on a Chip

Conventional atomic spectroscopy systems have many large components, whereas the compact, fully planar device developed at the University of California, Santa Cruz enables the study of atoms and molecules on a chip-based platform with integrated optics, said Holger Schmidt, associate professor of electrical engineering.

According to Schmidt, potential applications for the first monolithically integrated, planar rubidium cell on a chip include frequency stabilization for lasers, gas detection sensors, and quantum information processing. "To stabilize lasers, people use precision spectroscopy with bulk rubidium vapor cells. We could build a little integrated frequency stabilization chip that would do that more easily than a conventional frequency stabilization circuit," Schmidt said.

The key to the group's achievement is their development of hollow-core optical waveguides based on antiresonant reflecting optical waveguide (ARROW) principles. In previous publications, Schmidt and his collaborators have described other uses of ARROW waveguides integrated into chips using standard silicon fabrication technology.

To perform atomic spectroscopy, the researchers incorporated rubidium reservoirs into a chip, connecting the reservoirs to hollow-core waveguides so that the optical beam path is filled with rubidium atoms. The resulting vapor cell is completely self-contained and has an active cell volume about 80 million times smaller than a conventional cell, Schmidt said. "We used rubidium as a proof of principle, but this technique is applicable to any gaseous medium. So it has potentially far-reaching implications," Schmidt said.

In addition to its use in laser frequency stabilization, rubidium vapor is widely used in quantum optics experiments and has been used to slow the speed of light. "Fundamental concepts in quantum information processing have been demonstrated in principle using bulk rubidium systems. To be practical you can't have big optical tables in all the places you would want to use it, but now we can make this technology more compact and portable," Schmidt said.; Source: University of California - Santa Cruz