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Birefringent Ray Trace
Published in Russell A. Chipman, Wai-Sze Tiffany Lam, Garam Young, Polarized Light and Optical Systems, 2018
Russell A. Chipman, Wai-Sze Tiffany Lam, Garam Young
The optical properties of birefringent materials depend on the direction of the light’s polarization, as opposed to isotropic materials, which have identical properties in all directions. Isotropic and anisotropic materials are characterized by 3 × 3 dielectric tensors and 3 × 3 gyrotropic tensors. Ray tracing through birefringent materials is different from tracing through isotropic materials. Rays refracting into anisotropic media are decomposed into two rays with different propagation directions and orthogonal polarizations. These two rays are eigen-modes and propagate without change of polarization state. The ray tracing details are different for each type of birefringent materials: uniaxial, biaxial, and optically active materials (Figure 19.1).
Optical properties of materials
Published in David Jiles, Introduction to the Electronic Properties of Materials, 2017
We have touched briefly on the optical properties of materials in the early chapters, but here we must bring together the concepts of electron structure and the known optical properties of materials. This is done by identifying the allowed energy transitions which determine the main features of the optical spectrum. This means that we need to connect measured optical properties with the allowed electron energy levels. The major classification of electron transitions is here between transitions within the same band (intraband) and transitions between different bands (interband). The former are lower-energy transitions which lead to the high reflectivity of metals in the visible spectrum. The latter are higher-energy transitions which can lead to specific colours in materials. Various methods for measuring the optical properties are discussed including both conventional static optical measurements and differential techniques under external modulation of field, temperature or stress. Finally, the specialized topics of photoluminescence, and electroluminescence are discussed.
Composite, Birefringent, and Metamaterials
Published in H. Angus Macleod, Thin-Film Optical Filters, 2017
Although there seems to be an almost unlimited number of materials that can be used in thin-film optical coatings, they tend to have quite similar properties, and, in fact, because properties other than optical are also important, the number of materials actually used is still more limited. There is therefore an interest in extending the range of optical properties. Composite materials are essentially combinations of two or more materials to yield properties different from those of the components. Birefringent materials have optical properties that depend on direction. This may be a natural property of the material, or it may depend on anisotropic strain, but the birefringence we are considering here is usually the result of deliberate structuring of the material. Metamaterial is a relatively new term that can encompass all the others but is especially used to denote deliberately engineered materials that exhibit properties quite remote from those displayed by natural materials. A particular property that has attracted considerable attention is negative refraction.
Gamma radiation effect on the optical linear and nonlinear properties of PVA with trypan blue film
Published in Radiation Effects and Defects in Solids, 2023
Sawsan Sh. Fleifil, Qusay M. A. Hassan, Adil Muala Dhumad, H. A. Sultan, C. A. Emshary
Nonlinear optical (NLO) materials have attracted numerous investigations during the last three decades via studying the available ones, new synthesized and other’s properties have been improved by many methods. These materials are so important for the use in potential applications, viz. index of refraction modulation (1), all-optical switching (2), optical limiters (3), phase controlled by light (4), optical phase conjugation (5), frequency conversion (6), image processing (7), optical telecommunication (8), optical data storage (9) and optical computing (10). The optical properties of matters of importance are absorption, transmission, optical band gap values, dielectric constant, crystal structure, index of refraction, reflectivity, grain size, etc.
Insights into structural, electronic, optical and thermoelectric properties of WB and WAlB: a first principle study
Published in Philosophical Magazine, 2018
Priyanka Rajpoot, Anugya Rastogi, Udai Pratap Verma
In order to understand the response of materials to electromagnetic radiation, the study of optical properties is required. Optical properties of WB and WAlB have been calculated using the frequency-dependent dielectric function in the energy range 0–35 eV. The imaginary part of the dielectric function is calculated using the momentum matrix elements between occupied and unoccupied electronic states. The real part of the dielectric function, , is derived from the imaginary part through the Kramer–Kronig relations [43]. Other optical parameters such as refractive index, extinction coefficient, reflectivity, conductivity, absorption coefficient and energy loss function have been derived from the obtained real and imaginary parts of the dielectric function.
Novel method for the determination of the optical conductivity and dielectric constant of SiGe thin films using Kato-Adachi dispersion model
Published in Phase Transitions, 2021
Emna Kadri, Khaled Dhahri, Régis Barillé, Mohamed Rasheed
In this work, we report on the preparation and characterization of a series of thin films, with high crystallinity quality, covering the full compositional spectrum with a thickness of about 100 nm grown on Si substrates with a thickness of about 250 μm using MBE technique. It should be emphasized that the study presented herein has been conducted owing the results of previous work dealing with theoretical study of spectral response of ../Si solar cell as function of wavelength with different values of Ge fraction, suggesting that the enhancement of photocurrent is carried out by the emitter layer [14]. Furthermore, it is important to note that observed enhancement of the photocurrent is a signature of this particular heterojunction in comparison with conventional solar cell. Within the context of this theoretical study [15], we have shown that the improvement in the photocurrent is attributed to the increase in the Ge concentration, giving rise to the improvement of the absorption coefficient in the layer. The density of the minority carriers in the n-region () would, therefore, increases. At this juncture, it should be noted that, in general, the enhancement of the quantum efficiency of the active layer hangs mainly on the appropriate optical properties of the compound [16]. For this purpose, we will use the most powerful tool for studying the optical properties, that is the spectroscopic ellipsometry (SE). We are persuaded that the most helpful data set, allocating for an important extension of our familiarity with the optical properties of the thin films, will be achieved by measuring the ellipsometric curves. These curves will be obtained using polarized light to analyze thin layers on a reflecting substrate. The sensitivity of the Si1-xGex thin films are gained from the measurement of light polarization and phase shift between s- and p-components of reflected light rather that light intensity [17]. Utilizing these SE measurements, a new model is reported herein for the determination of the optical and the dielectric constant of thin films. More precisely the accent will be paid on achieving the determination of the electrical and dielectric properties of n-/p-Si heterojunction prepared by molecular beam epitaxy (MBE) technique. We shed light on the candidacy of n- /p-Si with x = 0.1, as potential heterojunctions for solar cells applications by correlating the optical properties with the electrical measurements. Another advantage of thin film cells is the promising opportunities they can offer with regards to reducing the cost of the component and to meeting the current high demand for silicon feed stock, Cuprous oxide (Cu2O) is metal oxide semiconductor material, which has attracted much attention in recent years due to its good optical and electrical proprieties [18,19].