Further guidance for broadband antireflection coating design

Willey, Ronald R.

doi:10.1364/ao.50.00c274

Cited by 15 publications

(6 citation statements)

References 10 publications

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“…Antireflective (AR) coatings/structures are needed for most of existing optical components and optoelectronic devices, ranging from glasses, polymers, and fibers to solar cells, photodetectors, light-emitting diodes, and laser diodes, to remove undesired optical loss and improve optical performance [1-3]. For advanced AR properties compared to the conventional AR coatings (i.e., very low reflection at broad wavelength ranges and large incident angles), subwavelength structures (SWSs) with tapered profile, which is inspired by insect's eye, have been developed [4-6].…”

Section: Introductionmentioning

confidence: 99%

Antireflective grassy surface on glass substrates with self-masked dry etching

et al. 2013

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Although recently developed bio-inspired nanostructures exhibit superior optic performance, their practical applications are limited due to cost issues. We present highly transparent glasses with grassy surface fabricated with self-masked dry etch process. Simultaneously generated nanoclusters during reactive ion etch process with simple gas mixture (i.e., CF4/O2) enables lithography-free, one-step nanostructure fabrication. The resulting grassy surfaces, composed of tapered subwavelength structures, exhibit antireflective (AR) properties in 300 to 1,800-nm wavelength ranges as well as improved hydrophilicity for antifogging. Rigorous coupled-wave analysis calculation provides design guidelines for AR surface on glass substrates.

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Section: Introductionmentioning

confidence: 99%

Antireflective grassy surface on glass substrates with self-masked dry etching

et al. 2013

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“…An appropriate choice of materials for the target wavelength range will lead to an optimized structure with better transmission characteristics than with inappropriate materials. A natural choice for antireflection coatings is to choose materials with refractive indices that gradually interpolate the refractive indices of the substrate and air, as in conventional indexmatching ARCs [17]. In addition, the initial thicknesses for each layer are an important factor for the initial geometry.…”

Section: Geometry For Arc Structuresmentioning

confidence: 99%

Broadband omnidirectional antireflection (AR) coating based on inverse transfer design towards high efficiency photovoltaic cells

Oduor

Menon

Omair

et al. 2023

Energy Harvesting and Storage: Materials, Devices, and Applications XIII

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The solar spectrum reaching Earth spans from ultraviolet to infrared wavelengths with a cutoff at around 2.5 µm. About 30% of the irradiance is absorbed by the atmosphere, and the rest is absorbed by the Earth's surface. The radiance available for generating renewable energy ranges from 400 nm to 2.0 µm. Silicon and III-V materials are used for photovoltaic (PV) cells. The PV cells reflect 30% of incoming radiation and to reduce this reflection, antireflection coating (ARC) is being used. Conventional techniques such as single or stacked multi-layer ARC or micro-nanostructures ARC are used. However, they lack in providing broadband and omnidirectional transmission, which limits its conversion efficiency in today's PV cells. We present broadband ARC achieved with an inverse transfer design, a prospect towards significantly high conversion efficiency PV cells. The ARC exhibit significantly increased transmission more than 96% over the solar spectrum ranges up to 2.5 µm, even with wide angles of incidence from ~ 0° to >70°. This transmission over the same angles of incidence, is significantly higher than that of ARC based on quarter-wavelength optical thickness (QWOT), a state-of-art ARC. The results also rival the transmission performance of state-of-the-art nanostructure-based ARC even at large angles of incidence, but are significantly easier to fabricate using standard e-beam evaporation and/or sputtering. The results show over broadband spectrum ranges, radiation back due to reflection makes to zero, leading to significantly increased conversion efficiency of the PV cells.

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“…The design of broadband anti-reflection (BBAR) coatings have been studied for many years 1,2,3,4,5 and yet even with new insights, it is still a challenging task to produce the performance as designed. The number of layers increases as the wavelength bandwidth increases and several of the layers become optically very thin, adding complexity and increasing error possibilities in the coating process.…”

Section: Introductionmentioning

confidence: 99%

Broadband anti-reflection coating for the meter class Dark Energy Spectroscopic Instrument lenses

Kennemore

Archer

Barbaria

et al. 2018

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III

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The Dark Energy Spectroscopic Instrument (DESI), currently under construction, will be used to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers, in turn, feed ten broad-band spectrographs. We will describe the broadband AR coating (360 nm to 980nm) that was applied to the lenses of the camera system for DESI using ion assisted deposition techniques in a 3 m coating chamber. The camera has 6 lenses ranging in diameter from 0.8 m to 1.14 m, weighing from 84 kg to 237 kg and made from fused silica or BK7. The size and shape of the surfaces provided challenges in design, uniformity control, handling, tooling and process control. Single surface average transmission and minimum transmission met requirements. The varied optical surfaces and angle of incidence considerations meant the uniformity of the coating was of prime concern. The surface radius of curvature (ROC) for the 12 surfaces ranged from nearly flat to a ROC of 611 mm and a sag of 140 mm. One lens surface has an angle of incidence variation from normal incidence to 40°. Creating a design with a larger than required bandwidth to compensate for the non-uniformity and angle variation created the ability to reduce the required coating uniformity across the lens and a single design to be used for all common substrate surfaces. While a perfectly uniform coating is often the goal it is usually not practicable or cost effective for highly curved surfaces. The coating chamber geometry allowed multiple radial positions of the deposition sources as well as substrate height variability. Using these two variables we were able to avoid using any masking to achieve the uniformity required to meet radial and angle performance goals. Very broadband AR coatings usually have several very thin and optically important layers. The DESI coating design has layers approaching 3 nm in thickness. Having sensitive thin layers in the design meant controlling layer thickness and azimuthal variation were critical to manufacturing repeatability. Through use of strategically placed quartz crystal monitors combined with stable deposition plumes, the manufacturing variability was reduced to acceptable levels. Low deposition rates and higher rotation rates also provided some stability to azimuthal variation.

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Further guidance for broadband antireflection coating design

Cited by 15 publications

References 10 publications

Antireflective grassy surface on glass substrates with self-masked dry etching

Antireflective grassy surface on glass substrates with self-masked dry etching

Broadband omnidirectional antireflection (AR) coating based on inverse transfer design towards high efficiency photovoltaic cells

Broadband anti-reflection coating for the meter class Dark Energy Spectroscopic Instrument lenses

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