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Design and analysis|6 Article(s)
Double-wavelength polarization insensistive beam splitter used in optical storage technology
Wenliang Wang, and Xiaohong Rong
Device to read/write data from optical storage units have polarization insensitive character at two separated wavelength. Based on a key four-layer structure and some matching layers, an initial thin film stack system is constructed. After optimized alternately by simplex and conjugate graduate algorithm, a double-wavelength polarization insensitive beam splitter with splitting ratio of R : T=50:50 at 650-nm wavelength and T > 93% at 780-nm wavelength is gained. The design result shows that the difference between reflectivity of P and S light around wavelength range of 630–670 and 760–800 nm with incident angle of 40o–50o is all very little. That indicates our design controls the polarization deviation well at two separate wavelengths with a reasonable range for both wavelength and incident angle. Device to read/write data from optical storage units have polarization insensitive character at two separated wavelength. Based on a key four-layer structure and some matching layers, an initial thin film stack system is constructed. After optimized alternately by simplex and conjugate graduate algorithm, a double-wavelength polarization insensitive beam splitter with splitting ratio of R : T=50:50 at 650-nm wavelength and T > 93% at 780-nm wavelength is gained. The design result shows that the difference between reflectivity of P and S light around wavelength range of 630–670 and 760–800 nm with incident angle of 40o–50o is all very little. That indicates our design controls the polarization deviation well at two separate wavelengths with a reasonable range for both wavelength and incident angle.
Chinese Optics Letters
- Publication Date: Jun. 14, 2013
- Vol. 11, Issue s1, S10106 (2013)
Numerical study of negative index material with low loss and polarization-independence in mid-infrared spectrum
Dengmu Cheng, and Longjiang Deng
We engineer numerically a negative index material (NIM) based on a square ring pairs (SRP) array and a thin wire net pairs (WNP). This metamaterial exhibits polarization-independence and low loss that is characterized by a figure of merit (FOM) up to 8.2 in mid-infrared spectrum. We engineer numerically a negative index material (NIM) based on a square ring pairs (SRP) array and a thin wire net pairs (WNP). This metamaterial exhibits polarization-independence and low loss that is characterized by a figure of merit (FOM) up to 8.2 in mid-infrared spectrum.
Chinese Optics Letters
- Publication Date: Jun. 07, 2013
- Vol. 11, Issue s1, S10105 (2013)
Calculation of infrared properties of low emissivity coatings containing metallic flake pigments
Le Yuan, Xiaolong Weng, and Longjiang Deng
The infrared emissivity of low emissivity coating can be significantly reduced by adding high content concentrations of parallel distributed metallic flake pigment. However, the infrared emissivity is very difficult to calculate by the existing theory models, such as the light scattering theory and traditional Kubelka-Munk radiative transfer model, because of shape and distribution anisotropy of flake pigments. Thus, the low emissivity coating is assumed to be the superposition structure of homogeneous layers and metallic flakes are approximately uniform and parallel arrangement in each layer. Based on geometric optics theory and Kubelka's layer model, considering multiple reflection, transmission and absorption of infrared radiation among different layers, the theoretical model is established to calculate the coating emissivity. The facts of binder, pigment concentration and thickness are also systematic discussed. The result shows that the law of influence on infrared emissivity can be correctly simulated by this theoretical model. Transparent binder, high volume concentration of thin flake pigment can facilitate to reduce infrared emissivity. Moreover, this model offers the possibility of predicting the infrared optical properties of coatings by their optical constants. The infrared emissivity of low emissivity coating can be significantly reduced by adding high content concentrations of parallel distributed metallic flake pigment. However, the infrared emissivity is very difficult to calculate by the existing theory models, such as the light scattering theory and traditional Kubelka-Munk radiative transfer model, because of shape and distribution anisotropy of flake pigments. Thus, the low emissivity coating is assumed to be the superposition structure of homogeneous layers and metallic flakes are approximately uniform and parallel arrangement in each layer. Based on geometric optics theory and Kubelka's layer model, considering multiple reflection, transmission and absorption of infrared radiation among different layers, the theoretical model is established to calculate the coating emissivity. The facts of binder, pigment concentration and thickness are also systematic discussed. The result shows that the law of influence on infrared emissivity can be correctly simulated by this theoretical model. Transparent binder, high volume concentration of thin flake pigment can facilitate to reduce infrared emissivity. Moreover, this model offers the possibility of predicting the infrared optical properties of coatings by their optical constants.
Chinese Optics Letters
- Publication Date: May. 21, 2013
- Vol. 11, Issue s1, S10104 (2013)
Design of antireflective coatings for AZO low infrared emissivity layer
Tingting Guo, Liqing Zheng, Jean Pierre Nshimiyimana, Xungang Diao, and Qiang Chen
In this letter, we investigate the structural, optical, and electrical properties of Al-doped ZnO (AZO) thin film coating prepared by direct current (DC) facing-target sputtering method at room temperature, of which the average optical transmittance is 81% between 400 and 700 nm while the sheet resistance is about 10 \Omega/. Then, based on this AZO coating, in order to enhance the transmittance, interfacial adhesion strength and weathering resistance, two kinds of antireflective coatings are designed for different application purposes. For the two kinds, the highest transmittances in the visible region (400–700 nm) can reach 86.9% and 81.8%, respectively. The design is performed using Macleod Optical Design software. In this letter, we investigate the structural, optical, and electrical properties of Al-doped ZnO (AZO) thin film coating prepared by direct current (DC) facing-target sputtering method at room temperature, of which the average optical transmittance is 81% between 400 and 700 nm while the sheet resistance is about 10 \Omega/. Then, based on this AZO coating, in order to enhance the transmittance, interfacial adhesion strength and weathering resistance, two kinds of antireflective coatings are designed for different application purposes. For the two kinds, the highest transmittances in the visible region (400–700 nm) can reach 86.9% and 81.8%, respectively. The design is performed using Macleod Optical Design software.
Chinese Optics Letters
- Publication Date: Apr. 19, 2013
- Vol. 11, Issue s1, S10103 (2013)
Tuning circular Bragg phenomenon of TiO2 sculptured thin f ilms with chiral structure
Difan Luo, Chendi Huang, and Shaoji Jiang
TiO2 chiral sculptured thin films (CSTFs) prepared using glancing angle deposition (GLAD) method based on electron beam evaporation are studied. The relationship between structural parameters and circular Bragg phenomenon (CBP) is investigated. Results demonstrate that, the central wavelength of Bragg regime red-shifts with the increasing pitch of helix, and peak value of selective transmittance will increase after adding more turns to the helix. After annealing, the central wavelength blue-shifts and the peak value rises. Tuning CBP by modulating the deposition parameters and annealing can optimize the performance of circularly polarized devices fabricated from CSTFs. TiO2 chiral sculptured thin films (CSTFs) prepared using glancing angle deposition (GLAD) method based on electron beam evaporation are studied. The relationship between structural parameters and circular Bragg phenomenon (CBP) is investigated. Results demonstrate that, the central wavelength of Bragg regime red-shifts with the increasing pitch of helix, and peak value of selective transmittance will increase after adding more turns to the helix. After annealing, the central wavelength blue-shifts and the peak value rises. Tuning CBP by modulating the deposition parameters and annealing can optimize the performance of circularly polarized devices fabricated from CSTFs.
Chinese Optics Letters
- Publication Date: Apr. 19, 2013
- Vol. 11, Issue s1, S10102 (2013)
Optical interference coatings–yesterday and today
Angus Macleod
Although they are common in nature and must certainly have been observed by early man, we have to wait till Newton for the first truly scientific study of what we now understand as interference effects in thin films. Young, Fresnel, and Maxwell all contributed and the theory was well established by the beginning of the 20th century. Coatings depending on interference, at this stage, were in their infancy and antireflection and decorative coatings, and color photography were the primary applications. By the middle of the 20th century, the situation had changed completely. Today almost the entire field of optics depends on interference optical coatings. This paper will start with a rapid account of the history and end with a survey of the range of interference coatings that are employed today with a fleeting glimpse of what might be in the future. Although they are common in nature and must certainly have been observed by early man, we have to wait till Newton for the first truly scientific study of what we now understand as interference effects in thin films. Young, Fresnel, and Maxwell all contributed and the theory was well established by the beginning of the 20th century. Coatings depending on interference, at this stage, were in their infancy and antireflection and decorative coatings, and color photography were the primary applications. By the middle of the 20th century, the situation had changed completely. Today almost the entire field of optics depends on interference optical coatings. This paper will start with a rapid account of the history and end with a survey of the range of interference coatings that are employed today with a fleeting glimpse of what might be in the future.
Chinese Optics Letters
- Publication Date: Apr. 24, 2013
- Vol. 11, Issue s1, S10101 (2013)
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