NIST develops chip-scale device to manipulate multiple laser beams

April 12, 2023

Controlled properties include wavelength, focus, orientation, and polarization; with applications in novel quantum devices.

Researchers at the National Institute of Standards and Technology (NIST) have developed a chip-scale device that can simultaneously control the wavelength, focus, direction of travel and polarization of multiple laser beams.

The ability to tailor these properties using a single chip “is critical to creating new types of portable sensors that can measure fundamental quantities such as rotation, acceleration, time and magnetic fields with unprecedented precision outside the confines of the laboratory,” NIST said.

Typically, a laboratory bench the size of a dining table is required to house the various lenses, polarizers, mirrors, and other equipment needed to manipulate even a single laser beam. However, many quantum technologies, including tiny optical atomic clocks and some future quantum computers, will require simultaneous access to multiple widely varying laser wavelengths within a small region of space.

integrated photonic circuit add optical metasurface

To solve this problem, NIST scientist Vladimir Aksyuk and his colleagues combined two chip-scale technologies: an integrated photonic circuit, which uses tiny transparent channels and other tiny components to guide light; and an optical metasurface. Such surfaces consist of glass wafers printed with millions of tiny structures that manipulate the properties of light without bulky optics.

Aksyuk and his team demonstrated that a single photonic chip can do the work of 36 optical elements while simultaneously controlling the direction, focus and polarization (the plane in which light waves vibrate as they propagate) of 12 laser beams split into four different wavelengths.

The team also showed that the tiny chip can direct two beams of different color to travel side by side, a requirement for some types of advanced atomic clocks. They report their findings in the journal Nature (Light: Science & Applications).

“Replacing optical benches filled with bulky optical components with simple semiconductor wafers that can be fabricated in a clean room is truly disruptive,” said Amit Agrawal, a member of the NIST team. “These technologies are required because they are robust, compact, and can be easily reconfigured for different experiments under real-world conditions,” he added.

Aksyuk noted that chip-based optical systems are being developed. For example, lasers are not powerful enough to cool atoms down to the ultra-low temperatures needed for tiny advanced atomic clocks.

While laser light normally excites atoms, causing them to heat up and move faster, the opposite happens if the frequency and other properties of the light are carefully chosen. After striking the atoms, laser photons induce the atoms to release energy and cool down so that they can be trapped by a magnetic field.

Even without cooling capabilities, the tiny optics “are a key stepping stone to building advanced atomic clocks on a chip,” Aksyuk said.