Talk “Low-cost and scalable manufacturing of optical metasurfaces in the visible using engineered optical materials”

December 13, 2023, 10:30 a.m. (CET)

Talk by Prof. Junsuk Rho, Pohang University of Science and Technology

Time: December 13, 2023, 10:30 a.m. (CET)
Venue: Seminar Room PI4, Pfaffenwaldring 57, Room 4-319
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We demonstrate low-cost, scalable manufacturing of optical metasurfaces with three approaches:
1) increasing a refractive index of resin with dielectric particle embedding for single-step nanoimprinting,
2) suppressing optical losses of hydrogenated amorphous silicon (a-Si:H) to apply complementary-metal-oxide-semiconductor technologies, and
3) high-index atomic layer deposited (ALD) structural resin.

We demonstrate the effectiveness of these materials in creating optical metasurfaces operating at different wavelengths in the infrared, visible, and ultraviolet spectra. Firstly, we achieve high efficiencies of up to 90.6%, 47%, and 60% with a-Si, TiO2, and ZrO2 PER at wavelengths of 940, 532, and 325 nm, respectively. Furthermore, we obtain a measured efficiency of 30% at a wavelength of 248 nm using ZrO2 PER metasurfaces. Secondly, by adjusting the deposition conditions of plasma-enhanced chemical vapor deposition, we engineer the bandgap of a-Si:H to enable low-loss operation, with minimum extinction coefficients as low as 0.082 at 450 nm. Using low-loss a-Si:H, we demonstrate efficient beam-steering metasurfaces with measured efficiencies of 42%, 65%, and 75% at 450, 532, and 635 nm, respectively, marking the first Si-typed metasurfaces working at the full visible. Finally, we manufacture highly efficient metalenses using hybrid ALD structural resin with deep-ultraviolet lithography at visible wavelengths. Their measured efficiencies approach 60.9%, 77.8%, and 64.8% at 450, 532 and 635 nm, making them suitable for ultrathin virtual reality devices. Our approaches using PER, low-loss a-Si:H, and hybrid ALD structural resin enables the low-cost, large-area manufacturing of efficient optical metasurfaces across different wavelengths, facilitating the commercialization of metasurface-based photonic devices.

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