Effect of Hydrophobic Modification on the Durability and Environmental Properties of Porous MgF_2 Antireflective Films

Conventional porous MgF2 antireflective films show poor environmental durability due to its hydrophilic nature.To improve the film environmental durability,hydrophobic porous MgF2 antireflective films are prepared by a methyl silicone-modified MgF2 sol.Effects of the methyl silicone proportions on the film properties are examined in order to control the wettability,peak transmittance,and environmental durability of the films.The modification of methyl silicone can increase the film hydrophobicity,thus decreases the adsorption of water,and improves the environmental durability.However,large amounts of methyl silicone could increase the film refractive index,resulting in the decrease in peak transmittance for films on BK7 glass.Films with 40% silicone show water contact angle of 110°,peak transmittance of 98.7%,and good environmental durability.The results of accelerated test show that the environmental durability of the porous MgF2 films modified with 40% methyl silicone is six times higher than that of the conventional films.

980 nm fiber grating external cavity semiconductor lasers with high side mode suppression ratio and high stable frequency

The coupling cavity theory is used to analyze the impact of high side mode suppression ratio （SMSR） on fiber grating external cavity semiconductor lasers （FGECSL）. The high SMSR and high stable frequency FGECSLs were obtained by experiment. The center wavelength is 974 nm, SMSR is 45 dB, the center wavelength change rate reaches 3.08 ppm/℃ in the temperature range of -20 to 80 ℃.

Facile and robust strategy to antireflective photo-curing coating through self-wrinkling

We reported a facile and bio-inspired strategy for obtaining antireflective （AR） coating through polymerization-induced self-wrinkling. Upon irradiation of light, the complex wrinkle micro-patterns with different morphologies were generated spontaneously on the surface of coating during photo-cross- linking, which enables the photo-curing coating can decrease reflection. The resulting photo-curing coating exhibits a high transmittance over 90% and low reflection below 5% ～ 8%, with an efficiency anti- reflection of 4% ～ 7%; compared to the flat blank coating. The successful application of these AR coatings with wrinkles pattern to encapsulate the thin film solar cells results in appreciable photovoltaic performance improvement of more than 4% ～ 8%, which benefits from the decrease of the light reflection and increase of optical paths in the photoactive layer by the introduction of wrinkling pattern. Furthermore, the efficiency improvements of the solar cells are more obvious, with a remarkable increase of 8.5%, at oblique light incident angle than that with vertical light incident angle