Optofluidic devices that dynamically respond to light stimuli have the potential to impart modern adaptive optics with intrinsic optical logic without the need for external power sources or feedback control. While photo actuation is typically associated with low energy efficiency compared with alternative modes of actuation, fluid lenses can be tuned with minimal work by generating small differential pressures across the surface of the lens to drive a change in focal length. In this study, we developed a wide aperture (9.5 mm) photothermally actuated lens that leverages spatially and thermodynamically informed design principles developed for resistively heated thermo-pneumatically actuated lenses. Using experimentally validated models to describe the curvature of pressurized elastomer-bound interfaces, we demonstrated phototunable modulation of the focal length from 124 mm to 90 mm in real time using 233 mW of 405 nm light over 30 s of irradiation with an estimated 8.2 µJ of mechanical work (10−4% efficiency). The initial focal length recovered after 60 s in the dark over three consecutive cycles of actuation. Additionally, the photoactuated response is shown to correlate well with the light intensity.
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Millimeter-scale focal length tuning with MEMS-integrated meta-optics employing high-throughput fabrication
Abstract Miniature varifocal lenses are crucial for many applications requiring compact optical systems. Here, utilizing electro-mechanically actuated 0.5-mm aperture infrared Alvarez meta-optics, we demonstrate 3.1 mm (200 diopters) focal length tuning with an actuation voltage below 40 V. This constitutes the largest focal length tuning in any low-power electro-mechanically actuated meta-optic, enabled by the high energy density in comb-drive actuators producing large displacements at relatively low voltage. The demonstrated device is produced by a novel nanofabrication process that accommodates meta-optics with a larger aperture and has improved alignment between meta-optics via flip-chip bonding. The whole fabrication process is CMOS compatible and amenable to high-throughput manufacturing.
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- Award ID(s):
- 2025489
- PAR ID:
- 10323244
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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