Nanostructures versus thin films in the design of antireflection coatings

Schallenberg, Uwe B.

doi:10.1117/12.896841

Cited by 4 publications

(2 citation statements)

References 59 publications

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“…Therefore, a variety of antireflection coatings are used to improve fibre decoupling efficiency, occupying an important place in the fibre laser technology and associated techniques. The Fresnel reflection can also be reduced using nanostructured gradient-index AR coatings [18,19]. If such a coating is fabricated directly on the fibre tip and has the refractive index gradually changing along the longitudinal axis (Z) from the refractive index of the core to that of ambient medium (typically air), it can significantly reduce the reflectivity over a very broad spectral range.…”

Section: Dlw On a Fibre Tip: Resultsmentioning

confidence: 99%

Optical Microstructures Fabricated with Direct Laser Writing Technique

Kowalczyk¹,

Nawrot

Zinkiewicz³

2014

Latvian Journal of Physics and Technical Sciences

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Three-dimensional photolitography, also known as Direct Laser Writing (DLW), is a powerful technique for fabrication of photonic microstructures. In this paper we present the basics of the relevant technology and discuss some features of the fabrication process. We also describe the experimental setup designed for making colour filters based on diffraction gratings, fibretip-integrated lens and anti-reflective coating designed for telecom wavelength (1550 nm). The results obtained demonstrate the DLW technique to be a promising fast prototyping fabrication method that may allow manipulating the properties of optical materials.

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Section: Dlw On a Fibre Tip: Resultsmentioning

confidence: 99%

Optical Microstructures Fabricated with Direct Laser Writing Technique

Kowalczyk¹,

Nawrot

Zinkiewicz³

2014

Latvian Journal of Physics and Technical Sciences

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“…Over the past decade, a surface sub-wavelength structure has been proposed as anti-reflective purpose to reduce the optical reflection and improve the light transmittance for broadband spectrum regions [2][3][4][5][6][7]. Moreover, it can overcome some puzzles of traditional anti-reflective films, such as poor adhesion, easy erosion, and element diffusion [8].…”

Section: Introductionmentioning

confidence: 99%

Broad-band anti-reflective pore-like sub-wavelength surface nanostructures on sapphire for optical windows

Lin¹,

Wang²,

Tian³

et al. 2018

Nanotechnology

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Compared with conventional anti-reflective film, an anti-reflective sub-wavelength surface structure provides an ideal choice for a sapphire optical window especially in harsh environments. However, it is still a challenge to obtain a sapphire anti-reflective surface microstructure because of its high hardness and chemical inertness. In this paper, combined with optical simulation, we proposed a facile method based on the anodic oxidation of aluminum film and following epitaxial annealing. Al thin film was deposited on a sapphire substrate by magnetron sputtering, and anodic oxidation was then performed to prepare surface pore-like structures on the Al film. Followed by two-step annealing, both the anodic oxidized coating and underlying unoxidized Al film were transformed totally into alumina. The parameters of anodic oxidation were analyzed to obtain the optimal pore-like structures for the antireflection in the mid-infrared and visible spectrum regions, respectively. Finally, the optimized surface sub-wavelength nanostructure on sapphire can increase the transmittance by 7% in the wavelength range of 3000-5000 nm and can increase 13.2% significantly for visible spectrum region, respectively. Meanwhile, the surface wettability can be also manipulated effectively. The preparation of surface pore-like sub-wavelength structure by the annealing of anodic oxidized aluminum film on sapphire is a feasible, economical and convenient approach and can find the applications for various optoelectronic fields.

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Microstructured gradient-index antireflective coating fabricated on a fiber tip with direct laser writing

Kowalczyk¹,

Haberko²,

Wasylczyk³

2014

Opt. Express

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We present a simple broadband gradient-index antireflective coating, fabricated directly on a single mode telecom fiber tip. A regular array of hemi-ellipsoidal protrusions significantly reduce the Fresnel reflection from the glass-air interface. The parameters of the structure were optimized with numerical simulation for the best performance at and around 1550 nm and the coating was fabricated with Direct Laser Writing. The measured reflectance decreased by a factor of 30 at 1550 nm and was below 0.28% for the 100 nm spectral band around the central wavelength. Compared to quarter wavelength antireflective coatings the demonstrated approach offers significantly reduced technological challenges, in particular processing of a single optical material with low sensitivity to imperfections in the fabrication process.

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Nanostructures versus thin films in the design of antireflection coatings

Cited by 4 publications

References 59 publications

Optical Microstructures Fabricated with Direct Laser Writing Technique

Optical Microstructures Fabricated with Direct Laser Writing Technique

Broad-band anti-reflective pore-like sub-wavelength surface nanostructures on sapphire for optical windows

Microstructured gradient-index antireflective coating fabricated on a fiber tip with direct laser writing

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