A new chip photonic circuit is born, which can convert a single laser beam into a variety of different new beams

Precisely shaping and controlling visible light beams is essential for diagnosing and studying human disease, and capturing the atoms that form the basis of the world's most accurate clocks, quantum computing, and many other quantum technologies.

Researchers at the National Institute of Standards and Technology (NIST) have designed an on-chip photonic circuit that can convert a single incident laser beam into a series of new beams, each with different optical properties.

(photo credit: NIST)

According to the report, the newly generated beam retains the frequency of the original beam while leaving the circuit from a different location on the chip. This allows scientists and engineers to select specific properties of one or more beams for specific applications.

When the beam enters the photon chip, it is directed to an area where a beam splitter divides the light wave into two parts. At each location, a thin layer of tantalum pentoxide's Swiss cheese-like structure alters many properties of the light wave, including its phase and polarization.

However, doing so often requires bulky optics that take up a lot of lab space. The new device designed by NIST could eventually eliminate the need for such optics and help miniaturize the latest generation of atomic clocks and other devices so they can be used practically. Small, portable atomic optical clocks could greatly improve navigation systems, especially underwater where there is no GPS.

High precision NC polishing aspherical lens

Most methods of shaping and directing light on a chip, including those that use metassurals, typically convert a single beam with one set of properties into a single beam with another set of different properties.

NIST researcher Grisha Spektor says their device, by contrast, can generate a large number of shaped beams from a single input beam. Researchers need to simultaneously bombard the atomic cloud with multiple laser beams from different directions to capture and cool the atomic cloud so that it can be used as the basis for atomic clocks. The latest generation of optical atomic clocks, which are likely to become the new international standard for defining the second, typically requires six lasers.

The circuit generates these beams within an ultra-thin tantalum pentoxide layer 150 nanometers thick. Tantalum pentoxide, commonly used in optical coatings, has a high refractive index and is almost completely transparent.

Using computer algorithms, Grisha Spektor and his colleagues printed Swiss cheese-like patterns on layers of tantalum pentoxide to produce multiple beams of light, each with different properties. Grisha Spektor says that because the photonic circuit consists of a single layer of material, it can be made relatively easily and scaled up to larger sizes as needed.

The results showed that the laser beam entered the chip through a channel that directed the light to several different locations within the chip. At each location, the optical flow is divided into two parts. The structure of tantalum pentoxide gives each stream a different phase - the position of the light wave in its crest and trough cycles.

Source: OFweek