Over the past several decades MEMS researchers and developers have demonstrated an extremely large number of microsensors for almost every possible sensing modality including temperature, pressure, inertial forces, chemical species, magnetic fields, radiation, etc. Recently, as a result of collaboration between few researchers at Harvard University, they have built a metasurface-based lens on top of a MEMS platform, creating a “lens-on-MEMS” device that focuses light in the MIR spectrum. The MEMS-integrated metasurface lens combines the best features of both technologies while reducing the size of the optical system. It measures 900 m in diameter and is 10 m thick. In this hybrid device, MEMS mirrors reflect scanned light, which the metalens then focuses without the need for an additional optical component, such as a focusing lens.
A 2D scanning MEMS platform controls the angle of the lens along two orthogonal axes by ± 9°, thus enabling dynamic beam steering. The device can be electrically controlled to vary the 2D angular rotation of a flat lens and hence the position of the focal spot by several degrees.
A close-up view of a metasurface-based flat lens (square piece) integrated onto a MEMS scanner. Integration of MEMS devices with metalenses will help manipulate light in sensors by combining the strengths of high-speed dynamic control and precise spatial manipulation of wavefronts.
The researchers yielded that for low angular displacements, the integrated lens-on-MEMS system does not affect the mechanical performance of the MEMS actuators and preserves the focused beam profile as well as the measured full width at half maximum.
The device could be used to compensate for off-axis incident light and thus correct for aberrations such as coma.
According to researchers, this proof-of-concept integration of metasurface-based flat lenses with 2D MEMS scanners could be extended to the visible and other parts of the electromagnetic spectrum, implying the potential for application across wider fields, such as MEMS-based microscope systems, holographic and projection imaging, lidar scanners and laser printing.
A circular metasurface-based flat lens has been integrated onto a MEMS scanner. Integration of MEMS devices with metalenses combines the strength of high-speed dynamic control with precise spatial manipulation of wavefronts.
Dense integration of thousands of individually controlled lens-on-MEMS devices onto a single silicon chip could lead to the creation of a new type of reconfigurable fast digital spatial light modulator that would allow a greater degree of control and manipulation of the optical field.
“This first successful integration of metalenses and MEMS, made possible by their highly compatible technologies, will bring high speed and agility to optical systems, and unprecedented functionalities,” said professor Federico Capasso.
Researchers say the eventual goal would be to fabricate all components of an optical system — the MEMS, the light source, and the metasurface-based optics — with the same technology used to manufacture electronics today.
“Then, in principle, optical systems could be made as thin as credit cards,” said Daniel Lopez, group leader of Nanofabrication and Devices at Argonne.