A convenient field-installable antireflection coating for optical fiber connectors and other components

Disc-shaped pellicles 15 microns thick are antireflection coated and cemented to the polished ends of optical fiber connectors. Excess loss due to increased fiber separation is a maximum of 10% (.46 dB), typically 3.8% (.16 dB) in graded index fibers; Fresnel back-reflections are reduced by a factor of more than 10.     

Imperfect antireflection coating effect reduction schemes for birefringent interleaver and optical communication systems

Chromatic dispersion (CD) caused by an imperfect antireflection coating is a great concern for optical engineers, and different techniques have been proposed to reduce CD in optical devices. In this article, we investigate two popular CD reduction techniques used in birefringent interleaver manufacturing and their effects on performance improvement of optical communication systems. Our results show that some CD reduction scheme bringing about a smaller CD ripple amplitude does not necessarily guarantee better system performance. This result can be used as a guideline for optical engineers working on reducing CD caused by an imperfect antireflection coating.     

离子束辅助淀积低温微光学元件红外宽带增透膜

简要叙述了锗基片微光学元件红外宽带减反膜的设计与制作。着重介绍了离子束辅助淀积制备该膜系的过程，给出了用该方法制作８～１２μｍ波段的减反膜的测试曲线，它具有峰值透过率高，在设计波长范围内的平均透过率大于９７％以上，膜层附着好，可以切割和擦洗，可以在室温和１００Ｋ低温下反复循环使用。     

Advanced polyimide varnish for optical fiber coating fabrication

Using one-step high-temperature polycondensation, soluble polyimide based on 9,9-bis-(4’-aminophenyl) fluorene and 3,3’, 4,4’-diphenyl oxide tetracarboxylic acid dianhydride is synthesized. Polyimide varnishes inN-methyl-2-pyrrolidone are prepared, and technological conditions of their deposition during fiber drawing are studied. A polymer coating thickness over 6 μm is achieved for a single application. It is demonstrated that the developed coating almost does not degrade for a long time at temperatures to 250 °C and completely protects the optical fiber surface from water penetration.     

抛光对光纤连接器回波损耗的影响

分别选用氧化铝和氧化硅材料的抛光砂纸,在施加不同抛光压力、抛光时间,以及抛光助剂等工艺条件下,实验研究了抛光对连接器回波损耗的影响规律。通过实验发现:氧化铝砂纸干式抛光使光纤连接器的回波损耗仅保持在32～38dB之间;氧化硅砂纸干式抛光会造成光纤端面污损,使得连接器的回波损耗降低到20dB以下;氧化铝与氧化硅砂纸湿式抛光均可使光纤连接器的回波损耗提高到45～50dB,但氧化铝砂纸湿式抛光会造成80nm以上的光纤凹陷。因此,制作高回波损耗的光纤连接器应优先选用氧化硅砂纸湿式抛光工艺,抛光时间应控制在20～30s。     

A novel trilayer antireflection coating using dip-coating technique

We report a new structure for broadband antireflection coating by dip-coating technique, which has minimal cost and is compatible with large-scale manufacturing. The coatings are prepared by depositing SiO 2 sol-gel film on a glass substrate, subsequently depositing SiO 2 single-layer particle coating through electrostatic attraction, and depositing a final very thin SiO 2 sol-gel film to improve the mechanical strength of the whole coating structure. The refractive index of the structure changes gradually from the top to the substrate. The transmittance of a glass substrate has been experimentally found to be improved in the spectral range of 400 1 400 nm and in the incidence angle range from 0 to at least 45 . The mechanical strength is immensely improved because of the additional thin SiO 2 sol-gel layer. The surface texture can be applied to the substrates of different materials and shapes as an add-on coating.     

Multiple fiber connectors for multimode fibers

We report on a multiple fiber connector for multimode fibers with a low insertion loss of ? 0.22 dB. The simple, standard photolithographic fabrication process involved can yield reproducibly the tight tolerances that are required for low loss connectors.     

Nanometer-thick Au-films as antireflection coating for infrared light

The optical properties of ultrathin Au films on silicon have been studied in the infrared over a wide frequency range from 200 to 10,000 cm(-1). Thick films show a Drude behavior; i.e., with increasing frequency the transmission increases; for films below the percolation threshold at about 5 nm a negative slope for the frequency-dependent transmission is observed. When the thickness is further reduced, between 1 and 3 nm an anomaly occurs: the relative transmission reaches maximum values above 100% compared with the bare substrate, indicating an antireflection coating of nanometer thickness for light of 5 microm wavelength. This anomaly can be explained in the framework of effective-medium theories.     

Piezoelectric film electro-deposition for optical fiber sensor with ZnO coating

The piezoelectric film electro-deposition for optical fiber sensor with ZnO coating is studied. The zinc oxide plating film is made on the copper surface directly by cathodic electro-deposition in the Zn(NO3)2 single salt aqueous solution systems. The influences of main experimental conditions on the properties of ZnO thin film in the electro-deposition processes are analyzed and a stable, practical and economic technique is obtained.     

Calibrated optical fiber power meters: Errors due to variations in connectors

We discuss potential errors in the measurement of optical fiber power when using a calibrated power meter with connectors of various types and from different vendors. Data are given on the error and standard deviation due to biconic connectors from a limited number of vendors. We speculate that the error is due to reflecting surfaces on the connector end. To confirm the hypothesis, we tested two connectors whose reflective ends have noticeable differences. The data illustrate the variability seen among connectors. Our data indicate that a user should expect measurement error in most cases. We issue a call for caution based on the results.     

Calibrated optical fiber power meters: Errors due to variations in connectors

We discuss potential errors in the measurement of optical fiber power when using a calibrated power meter with connectors of various types and from different vendors. Data are given on the error and standard deviation due to biconic connectors from a limited number of vendors. We speculate that the error is due to reflecting surfaces on the connector end. To confirm the hypothesis, we tested two connectors whose reflective ends have noticeable differences. The data illustrate the variability seen among connectors. Our data indicate that a user should expect measurement error in most cases. We issue a call for caution based on the results.     

Colloidal subwavelength nanostructures for antireflection optical coatings

A two-dimensional (2D) subwavelength nanostructure for antireflection coating is fabricated upon a transparent substrate. Self-assembled 2D colloidal crystals are used as a nanoscale composite material with controlled thickness and low refractive index. The feature size of the structure is approximately 105 nm. The structure is used for antireflection coating, and the measured reflectivity of a glass substrate is reduced to 0.3%. Enhanced transmission through the substrate is also observed.     

High-efficiency antireflection nanostructural optical coatings for solar cells

Potentialities of PMMA composite films with silver nanoclusters as highly effective nanostructural optical antireflection coatings of silicon solar cells are investigated in a wavelength range from 400 to 1100 nm.     

一种简易的光纤光栅涂覆装置

阐述了对裸光纤光栅进行涂覆的原理和必要性。设计了一种简易可行的光纤光栅涂覆装置。该装置简单灵活,成本较低,尤其适合于长度较长的光纤光栅的一次性涂覆,涂层厚度灵活可调。以啁啾光纤光栅为例进行了涂覆实验,涂层光滑均匀,涂覆后的光栅强度得到了增强,抵抗机械应力的能力得到了提高,使用起来更方便。对光栅在涂覆前后分别作了特性参数测试。结果表明,光栅特性基本上不发生变化,性能未劣化,光纤光栅的涂覆简单易行。     

Realization of a near-perfect antireflection coating for silicon solar energy utilization

To harness the full spectrum of solar energy, Fresnel reflection at the surface of a solar cell must be eliminated over the entire solar spectrum and at all angles. Here, we show that a multilayer nanostructure having a graded-index profile, as predicted by theory [J. Opt. Soc. Am. 66, 515 (1976); Appl. Opt. 46, 6533 (2007)], can accomplish a near-perfect transmission of all-color of sunlight. An ultralow total reflectance of 1%-6% has been achieved over a broad spectrum, lambda = 400 to 1600 nm, and a wide range of angles of incidence, theta = 0 degrees-60 degrees . The measured angle- and wavelength-averaged total reflectance of 3.79% is the smallest ever reported in the literature, to our knowledge.     

格兰泰勒棱镜高性能宽带减反射膜的优化设计及性能测试

格兰泰勒棱镜在光学领域有着重要的应用,透过比的高低和有效带宽的大小,直接影响着棱镜的品质.为了提高棱镜的透射率,拓宽有效使用带宽,借助于计算机辅助设计方法,设计了高性能多层减反射膜系:选用合适的光学薄膜材料,利用电子束蒸镀,借助于离子源辅助蒸镀,制作了高性能的宽带减反射膜.测试结果表明:平均剩余反射率小于0.5%,有效使用带宽在可见光区大于100 nm,达到了设计要求,提升了棱镜的品质.     

Similarity of optical properties of hydrides and semiconductors for antireflection coatings

The electronic structure and optical properties of the complex hydrides Ca₂FeH₆, Ca₂RuH₆, Mg₂FeH₆, Mg₂RuH₆, Sr₂FeH₆, Sr₂RuH₆ and Sr₂OsH₆ were studied using first-principles calculations. Optical spectra of the hydrides were compared with those of SiN _x , In₂O₃ and ZnO determined from theoretical calculations and measured experimentally. Based on an analysis of band structure, it is found that the electrical conductivity of the hydrides is expected to be poor. However, optical properties of the hydrides in the energy range 0–3 eV are found to be almost the same as those of SiN _x , In₂O₃, ZnO and TiO₂. Hydrides are suggested to be used as antireflection layers and for passivation of surface and bulk defects. This finding could be useful for electronic device technology including solar cells.     

Broad multilayer antireflection coating by apodized and chirped photonic crystal

In this work, a new examination had been carried out to create a multilayer which acts as an antireflection coating. It has been shown that applying an apodization to a one dimensional photonic crystal can significantly enhance the total optical transmission in the structure. The transmission characteristics of the apodized grating are analyzed. So, in order to achieve a wideband of total transmission, the number of layers and the apodization profile should be optimized. Then, chirping was introduced to the apodized structure to improve the system transmission. The structure was investigated numerically according to its number of layers. Through accurate control of the design parameters, reflectance can achieve a value less than 0.05% across a large range of wavelengths. The enhancement of optical transmission in this structure is very important since the performance of a number of optical devices could be improved.     

Spiral search method for designing a wide angular broadband visible antireflection coating

A spiraling search method is applied to design a wide angular visible antireflection (AR) coating with an incident angle of up to 50° above normal. Only a two-material multilayer system with high- and low-index is used in the design. It is shown that the maximum visible reflectivity can be reduced to below 1.26%, and that the total average wide-angle visible spectral reflectivity can be reduced to lower than 0.33%, respectively. Not only is the wide-angle visible AR performance in the designed range very acceptable, but it is found that the visible reflectivity for that incident angle beyond 50° can also be decreased.