New Chip Photonic Circuits Created To Convert A Single Laser Beam Into Many Different New Beams

Accurately shaping and controlling visible light beams is critical to diagnosing and studying human diseases and capturing the atoms that form the basis of the world's most accurate clocks, quantum computing and many other quantum technologies.
Recently, researchers at the National Institute of Standards and Technology (NIST) announced the design of a photonic circuit on a chip that can convert a single incident laser beam into a series of new beams, and make each beam have different optical properties.

According to the report, the newly generated beams retain the frequency of the original beam while leaving the circuit from different locations on the chip. This allows scientists and engineers to choose the specific characteristics of one or more beams for a particular application.
As the beam enters the photonic chip, it is directed to an area where a beam splitter divides the light wave into two parts. At each location, a thin Swiss-cheese-like layer of tantalum pentoxide alters many of the properties of the light wave, including its phase and polarization.
Doing so, however, typically requires bulky optics that take up a lot of lab space.The new device designed by NIST could ultimately eliminate the need for such optics and help miniaturize the latest generation of atomic clocks and other devices so that they can actually be used. Small, portable atomic optical clocks could greatly improve navigation systems, especially underwater where GPS is not available.
High-precision CNC-polished aspheric lenses
Most methods of shaping and directing light on a chip, including those using hypersurfaces, typically involve converting a single beam of light with one set of properties into a single beam of light with another set of different properties.
In contrast, says NIST researcher Grisha Spektor, their device can generate a large number of shaped beams from a single input beam. The researchers need multiple laser beams bombarding the atomic cloud simultaneously from different directions to capture and cool the cloud so it can be used as the basis for an atomic clock. The latest generation of optical atomic clocks, which are likely to become the new international standard for defining the second, typically require six laser beams.
The circuit generates these beams within an ultra-thin 150-nanometer-thick layer of tantalum pentoxide. Tantalum pentoxide, typically used in optical coatings, has a high refractive index and is almost completely transparent.
Using computer algorithms, Grisha Spektor and his colleagues imprinted the tantalum pentoxide layer with a Swiss cheese-like pattern to produce multiple beams, each with different properties.Grisha Spektor says that because the photonic circuit consists of a single layer of material, it can be fabricated with relative ease and scaled up to larger sizes as needed.
The results show that the laser beam enters the chip through a channel that directs light to several different locations within the chip. At each location, the optical flow is split into two parts. The structure of tantalum pentoxide gives each stream a different phase - the position of the light wave in its peak and trough cycles.