A chip-level device that can manipulate multiple lasers has been developed in the United States

     On April 10, researchers at the National Institute of Standards and Technology (NIST) announced an important development: They have successfully developed a chip-level device that can simultaneously manipulate the wavelength, focus, direction of motion, and polarization of multiple laser beams. The results were published on April 3 in the journal Light: Science & Applications.

     The ability to customize these characteristics using a single chip is critical to building new types of portable sensors that can measure fundamental parameters such as rotation, acceleration, time and magnetic fields with unprecedented accuracy beyond the limits of the laboratory, NIST notes.

     Typically, lab tables need to accommodate a variety of lenses, polarizers, mirrors, and other equipment that even requires manipulating a laser beam. However, many quantum technologies, including tiny optical atomic clocks and some future quantum computers, will require simultaneous access to multiple lasers with widely varying wavelengths in a small region of space.

Integrated photonic circuit + optical metasurface brings new possibilities

     To solve this problem, NIST scientist Vladimir Aksyuk and his team members combined two chip-scale technologies: 1) Integrated photonic circuits, which use tiny transparent channels and other tiny components to direct light; 2) An optical metasurface composed of glass wafers. The chip is imprinted with millions of tiny structures that can manipulate the properties of light without the need for bulky optics.

     The team's results demonstrate that a single photon chip can simultaneously control the direction, focus and polarization (the plane at which light waves vibrate as they travel) of 12 laser beams divided into four different wavelengths. They also demonstrated that the microchip could direct two different colored light beams to move in parallel with each other, which is exactly what some types of advanced atomic clocks need

     Three components: an evanescent coupler (EVC), which couples light from one device to another; Supergratings (MGS), tiny surfaces imprinted with millions of tiny holes, scatter light like large diffraction gratings; There is also a glass wafer metasurface (MS) covered with millions of columnar structures that act as a lens. (photo credit: NIST)

Instead of big, clunky optical workstations

     Amit Agrawal, a member of the NIST team, described the achievement as "a real game changer" by making it easy to replace an optical bench filled with bulky optical components with a simple semiconductor wafer that can be manufactured in a clean room. In addition, this chip-level device is robust and compact and can be easily reconfigured for different experiments under real-world conditions.

     Aksyuk noted that such chip-based optical systems are still under development due to a number of limitations. Lasers, for example, are not strong enough to cool atoms to the ultra-low temperatures needed to miniaturize advanced atomic clocks. While lasers typically power atoms, causing them to heat up and move faster, the opposite is true if the frequency and other properties of the light are carefully selected. In hitting the atoms, the laser photons induce them to give up energy and cool down so they can be captured by the magnetic field.

    Even without the cooling capability, the tiny optical system is a "key stepping stone" to building advanced atomic clocks on a chip, Aksyuk said.