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High Harmonic Generation
Published in Hitendra K. Malik, Laser-Matter Interaction for Radiation and Energy, 2021
One of the most essential uses of nonlinear processes is to generate new frequencies from a fixed wavelength laser. To analyze this, let us consider an optical electric field incident on a non-centrosymmetric optical medium, which is composed of two different frequency components. This can be represented as Et=E1e-iω1t+E2e-iω2t+c.c.
Field study of bi-directional loading test in PHC pipe piles based on fiber Bragg grating sensors
Published in Airong Chen, Xin Ruan, Dan M. Frangopol, Life-Cycle Civil Engineering: Innovation, Theory and Practice, 2021
L.C. Gao, G.L. Dai, Z.H. Wan, M.X. Zhu, W.M. Gong
FBG sensors are a kind of reflector with a wavelength selection function, which are made of fiber grating, as shown in Fig. 1. When light with a certain bandwidth passes through the sensor, light satisfying a certain condition is reflected back, and the wavelength variation due to external factors is then measured by a demodulation device. According to the relationship between the wavelength variation value and physical quantity, the physical quantity is determined (Lee et al. 2006; Pelecanos & Soga 2018; Zheng et al. 2019). According to the fiber coupled-mode theory, the Bragg grating wavelength λB is related to the grating period Λ and the effective refractive index of the fiber core. The Bragg grating wavelength λB satisfies the following equation: λB=2neffΛ where λB is the reflected wavelength, neff is the refractive index defined as the ratio of the light speed in vacuum to that in the optical medium, and Λ is the grating period.
Optical Fiber Hydrophone Systems
Published in Shizhuo Yin, Paul B. Ruffin, Francis T. S. Yu, Fiber Optic Sensors, 2017
Another approach to overcome polarization fading is the use of the Faraday rotation mirror (FRM) at each sensor head in Michelson interferometer-based sensor systems, demonstrated by Kersey et al. [53]. The Faraday effect denotes the nonreciprocal polarization rotation of a light signal as it passes through an optical medium within a magnetic field. The FRM incorporates a Faraday rotator in front of the mirror. It is this element that provides the nonreciprocal 45° rotation of the state of polarization each time the light passes through it. Situated at the end of an optical fiber, the Faraday rotation mirror is designed to rotate a signal’s state of polarization (SOP) by 45° twice: once when the light enters, and again when the light is reflected back into the fiber. Since the Faraday effect is nonreciprocal, the SOP is rotated by 90° with respect to the original signal. These rotations, applied in combination with a reversal of the polarization state’s handedness upon reflection at the mirror interface, yield a state perpendicular to the original signal. In this way, any SOP fluctuations that occur along the fiber anywhere between the source and the FRM are exactly compensated and their unwanted effects neutralized.
Synthesis of silver nanoparticles formed by Chaerophyllum macrospermum and Eremurus spectabilis biomaterial and investigation of photovoltaic parameters by adding silicon phthalocyanine
Published in Journal of Coordination Chemistry, 2023
Mehmet Salih Ağırtaş, Ömer Ödemiş, Derya Güngördü Solğun, Aslıhan Aycan Tanrıverdı, Abdullah Özkartal
Photonics, the science and technology that uses light, attracts researchers for the discovery of new photonic properties and the development of technologies with new compounds and products [27]. Materials to be used in photonics have found great success as waveguides. Ground-activated waveguides constitute a potentially important system to act as an effective optical medium for light dispersal and luminescence amplification [28]; there are specific systems used to increase the effectiveness of solar cells [29,30]. The strategy is to use light shedding to improve the optical density of solar cells by reducing the thickness of the absorber layer [31]. This lowers the material budget value and improves the mechanical flexibility of devices in applications while also making photovoltaic properties efficient [32]. Both the back surfaces and the front surfaces are very important to increase the length of the optical path inside the absorber layer and scattering light [33]. Application in very efficient Si cells has yielded superior efficiency in those achieved with optimized periodic texturing [34]. The photo response of semi-metal complexes and the way they are affected by the environment can be predicted [35].
A device of XOR logic gate and multiscale sensing based on layered topology
Published in Waves in Random and Complex Media, 2023
Jun-Yang Sui, You-Ming Liu, Hai-Feng Zhang
As a high electron mobility semiconductor material with a gyratory frequency in the terahertz (THz) range, InSb increases the non-reciprocity of EWs in positive and negative propagation due to its dispersion and gyratory properties and the magneto-optical effect exhibited under the action of magnetic fields [15,16], which makes InSb widely studied and used in THz isolators and absorbers. Based on the cyclotron characteristics of InSb in the THz band, Fan et al. proposed a tunable THz isolator with a periodic structure of semiconductor magnetic plasma, which had the advantages of non-mutual easiness, low loss, and high isolation bandwidth [17]. Wan et al. studied unidirectional absorbers with narrow band angle polarization-sensitive regions based on the quasi-periodic structure of InSb, using PBG to generate a wide band of absorption bands and whose polarization separation and non-reciprocal ability could be adjusted by temperature and magnetic induction intensity [18]. In addition, the enhancement of non-reciprocal phenomena is closely related to the increase in the angle of the incident light, the increase in the frequency of plasma rotation, the decrease in the thickness of the magneto-optical medium, and the opposite direction of the external magnetic field [19].
Tuneable optical diffractive structures from liquid crystalline materials incorporated into periodic polymeric scaffolds
Published in Liquid Crystals, 2023
D. Bošnjaković, X. Zhang, I. Drevenšek-Olenik
The gratings modelled in this work, with D ~ 10 μm and Λ = 5 μm, according to the Gaylord and Moharam classification [47], belong to an intermediate diffraction regime, which is the regime between the thin (Raman-Nath) and thick (Bragg) gratings. Consequently, analytical results are very difficult to be obtained. Also, the scalar diffraction theory is not accurate enough. Therefore, to describe diffraction properties of such gratings it is necessary to use numerical methods. One such method, which is used to describe the propagation of light within periodically modulated optical medium, is the RCWA based on the coupled-wave theory (CWT) [48]. The RCWA is focused on solving Maxwell’s equations that describe the behaviour of the electromagnetic field in three regions: the incident/reflection region, the grating region and the transmission region (see Figure 1(b)). The frequency domain form of the Maxwell’s equations for the configuration as shown in Figure 1 (in the absence of free charges and free currents) is given by [49]