Metasurfaces Enable Low-Loss Integrated Photonics Platform

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A University of Delaware (UD) research team has designed an integrated photonics platform using metasurfaces. To limit the loss of data, the team fabricated a high-contrast transmitarray (HCTA)-based metalens on a silicon-based chip programmed with hundreds of tiny air slots to enable on-chip parallel optical signal processing.

The 1D metalens has a numerical aperture up to 2.14, which can focus light to within 10 µm with less than 1 dB loss. Computational tasks based on Fourier transformation (FT) can be performed by cascading multiple layers of the HCTA-based metalenses. To demonstrate FT and spatial differentiation, the researchers layered three metasurfaces together.

The platform is foundry fabrication-compatible, ultracompact, and designed to achieve on-chip wavefront transformation with low insertion loss and broadband operation. “This is the first paper to use low-loss metasurfaces on the integrated photonics platform,” professor Tingyi Gu said. “Our structure is broadband and low loss, which is critical for energy-efficient optical communications.” 

A research team at the University of Delaware fabricated a metalens on a silicon-based chip programmed with hundreds of tiny air slots, enabling parallel optical signal processing all within the chip. Courtesy of Tingyi Gu and Zi Wang.

A UD research team fabricated a metalens on a silicon-based chip programmed with hundreds of tiny air slots, enabling on-chip parallel optical signal processing. Courtesy of Tingyi Gu and Zi Wang.

The UD researchers said their device is smaller and lighter than conventional devices of its type. It doesn’t require the manual alignment of lenses, so it is more scalable compared to the traditional free-space optics platforms.

The team’s experimental demonstration of the functional HCTA-based metalens could open new directions for on-chip diffractive optical systems. The on-chip metasurface could be integrated with multimode waveguides to perform mode transformation in mode division multiplexing systems.

The 1D metasurface design could facilitate novel on-chip systems with low power consumption and ultracompact dimensions, including on-chip spectrometers, light detection and ranging devices, and diffractive optical computational circuits.

“It’s just much faster than conventional structures,” said Gu. “There are still a lot of technical challenges when you try to actively control them, but this is a new platform we are starting with and working on.”

Parts of the device were fabricated in the UD Nanofabrication Facility (UDNF) and at AIM Photonics in Rochester, N.Y.

The research was published in Nature Communications ( 


Published: November 2019
A metalens, short for "metasurface lens," is a type of optical lens that uses nanostructured materials to manipulate light at a subwavelength scale. Unlike traditional lenses made of glass or other transparent materials, metalenses do not rely on the curvature of their surface to refract or focus light. Instead, they use carefully engineered patterns of nanostructures, such as nanoscale antennas or dielectric structures, to control the phase and amplitude of light across the lens's surface....
integrated photonics
Integrated photonics is a field of study and technology that involves the integration of optical components, such as lasers, modulators, detectors, and waveguides, on a single chip or substrate. The goal of integrated photonics is to miniaturize and consolidate optical elements in a manner similar to the integration of electronic components on a microchip in traditional integrated circuits. Key aspects of integrated photonics include: Miniaturization: Integrated photonics aims to...
Research & TechnologyeducationAmericasUniversity of DelawareMaterialsmetamaterialsmetalensmetasurfacehigh-contrast transmitarrayOpticsintegrated photonicssilicon photonicslenseslow-lossCommunicationson-chip optical systemssemiconductorsTech Pulse

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