Yeuh-Yeong Liou

Designing a Broadband Visible Antireflection Coating by Jumping Search Method

A jumping search method is applied to the design of a normal-incidence antireflection coating for the 400–750 nm spectrum regions. A search algorithm that includes jump turning and optimal elimination is successively used to optimize the visible antireflection performance and to simplify the design structure. It is shown that the average visible reflectivity of the jumping search antireflection coating designs of a two-material 40-layer system is reduced to approximately 0.064–0.079%, and the final designs are reduced to 14–16-layered structures.

Designing Wideband Visible Antireflection Coating Using Spiral Search Method

A synthesis method based on a spiraling search algorithm is applied to design a low-loss normal-incidence wideband visible antireflection coating. The design algorithm of the spiraling search is straightforward and the resultant visible antireflection (AR) performance is fairly good. It was shown that the average visible spectral reflectivity over the 400–750 nm region of the final design, obtained by the spiraling search method for a two-material 50-layer system, can be reduced to lower than 0.044%, that the maximum visible reflectivity can be reduced to less than 0.44%, and that the residual reflectivity in the mainly visible region of 415–740 nm can be reduced to below than 0.066%.

Universal broad-band antireflection coating designs for substrates in the visible spectral region

We have designed broad-band normal-incidence antireflection coatings over the visible spectral region for a set of eight various substrates with indices 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75 and 1.784. It is shown that the calculated average reflectance of the eighty-layer flip–flop antireflection coating design for substrates over the 400–750 nm spectral region can be reduced to less than 0.34%, which is acceptable.

Minimizing Search Method for Wideband Visible or Wideband Infrared Antireflection Coating Design

A design algorithm based on the minimizing search technique was proposed for designing the normal-incidence wideband visible or wideband infrared multilayer antireflection coating. The method utilized a tuning operation of the thickness of sublayers first, and then refined the antireflective performance and simplified the design by a layer minimizing operation. It was shown that the average visible spectral reflectivities of three-material thirty-layer and two-material thirty-layer minimizing search antireflection coating designs for glass substrates were reduced to less than 0.054% and 0.056% with a 12-layer structure, and the average infrared reflectivity of a two-material forty-layer minimizing search antireflection coating design for a germanium substrate over the broadband spectral region of 7.7–12.3 µm was reduced to less than 0.488% with a 22-layer structure.

Designing a Broadband Visible Antireflection Coating by Flip-Flop Tuning Search Technique

A design procedure of a broadband multiplayer antireflection coating is proposed. The design algorithm based on the flip-flop operation of the indices of layers is used first, and the tuning operation of the thickness of layers is applied afterward to improve the performance and to simplify the structure of the final solution. The final design, obtained by the flip-flop tuning search technique of a three-material 100-layer system starting with low indices for all ayers, is a nine-layer structure, and the average reflectivity over the visible spectral region is reduced to lower than 0.16%. It is shown that the structure designed by three-material flip-flop tuning is much simpler and its performance is better compared with the AR coating design obtained by the flip-flop synthesis method.

Design of Broadband Visible or Near-Infrared Antireflection Coating Based on Vibrating Search Approach

In this study, we present a numerical design approach, based on a vibrating search algorithm, to design a very low-loss normal-incidence broadband visible (vis) or near-infrared (NIR) antireflection (AR) coating. The vibrating search method involves the vibration adjustment and vibration-eliminating operations, which are utilized successively to improve the AR performance and simplify the design structure. Not only is the design algorithm very simple, the resultant broadband AR performance is also relatively good. The mean spectral reflectances of the AR coating designs in the visible region, 400–750 nm, and in the NIR region, 800–1600 nm, for a two-material multilayer system and obtained by the vibrating search method, can be reduced below 0.040 and 0.064%, respectively.

Optimization of Broadband Visible or Near Infrared Antireflection Coating Design by Scanning Search Method

A novel design algorithm based on a scanning search approach for designing a high-performance normal-incidence broadband visible or near infrared antireflection (AR) coating was proposed. The scanning search method consisting of scanning and elimination operations can be successively carried out to improve the AR performance and simplify the design structure; its design algorithm was straightforward and the resulting broadband AR performance was fairly good. It was shown that the average spectral reflectivities of the final designs in the visible region of 400–750 nm and in the NIR region of 800–1600 nm, obtained by the scanning search method of a two-material system, can be reduced below 0.042 and 0.085%, respectively.

Design of Universal Broadband Visible Antireflection Coating for Commonly Used Glass Substrates

We designed a universal broadband visible antireflection coating for glass substrates with refractive indices ranging from 1.45 to 1.90 by a jumping search technique. The jumping search algorithm, based on the searches of layer-thickness jump tuning and layer jump elimination, was used to refine the mean visible antireflection performance and simplify the design structure of a multilayer system. It was shown that the universal visible antireflection coating designs for a set of 10 different substrates with the refractive indices of 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, and 1.90, obtained by different types of jumping search of a two-material 50-layer system, were reduced to 18–22-layered structures and their total average universal visible reflectivities reduced to approximately 0.307–0.309% were acceptable.

Design of Wide-Angular-Incidence Antireflection Coating over Visible Spectral Region

A jumping search algorithm is applied to achieve a broadband visible antireflection coating design for a wide-angular-incidence with an incident angle of up to 45° from the normal. It is shown that the maximum wide-angular visible spectral reflectance, obtained by different types of jumping search for a two-material 20-layer system, is reduced to less than 0.869% with 14-layer structures, and the maximum average visible spectral reflectance for incident angle lying in the range of 0–45° is reduced to below 0.646%.

Digital designs of broadband visible antireflection coating for wide angular incidence

A design algorithm based on a modified minimizing search technique is applied to design a visible antireflection coating for a wide angular incidence with an angle up to 30° from the normal. The design approach consisting of tuning and minimizing operations is effective in refining the antireflective performance and simplifying the design structure of the desired solution. It is shown that the maximum wide angular visible spectral reflectance of minimizing search antireflection coating designs for a three-material 60-layer system is reduced to less than 0.490% with 15–21-layered structures, and the average visible spectral reflectance for each incident angle is reduced to below 0.137%.