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Tytuł:
Numerical analysis of slow and fast light effect in semiconductor optical amplifier with certain facet reflection
Autorzy:
Qin, Cui
Jiang, Yu
Zhen, Li
Powiązania:
https://bibliotekanauki.pl/articles/2172851.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
semiconductor optical amplifier
slow light
fast light
coherent population oscillation
Opis:
In this paper, the slow and fast light (SFL) effects of the semiconductor optical amplifier (SOA) having certain facet reflections are theoretically investigated. The theoretical model is used to account for the SFL phenomenon causing the coherent population oscillation. The influence of the current modulation frequency, the value of the current, the linewidth enhancement factor, facet reflectivity as well as the relative phase of the modulated current on the phase delay in the SOA are studied. It is demonstrated that the SFL effect could be controlled by the modulation frequency, the value and relative phase of the current. Finally, it is shown that the magnitude of the SFL delay could be tuned by a change in the linewidth enhancement factor as well as the facet reflectivity of the SOA.
Źródło:
Optica Applicata; 2022, 52, 4; 655--667
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of a weak ion beam treatment of emission layer on the top emission polymer light-emitting diode
Autorzy:
Gong, T
Gwag, J S
Powiązania:
https://bibliotekanauki.pl/articles/174367.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
organic light emitting diode
light-emitting polymer
top emission
optical device
ion beam
surface treatment
Opis:
This study examined the influence of a weakly treated emission layer on ion beam processing for the performance of top emission polymer light-emitting diodes with an invert structure (top ITO as the anode). The emission layer used in this experiment was a polymer type SY, Livilux PDY-132 provided by Merck & Co. The surface of the emission layer was modified by a low energy ion beam treatment to obtain hydrophilic functional groups and improve the wettability. As a hole transfer layer, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS, CLEVIOS AI 4083, Heraeus) was spin-coated on the ion beam treated emission layer and showed good adhesion properties. Consequently, through such an ion beam treatment that promotes the interface properties of these two layers, a uniform light emitting area was obtained and the light intensity in a top emission polymer light-emitting diode was improved.
Źródło:
Optica Applicata; 2014, 44, 4; 567-574
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convergence of Monte Carlo algorithm for solving integral equations in light scattering simulations
Autorzy:
Kraszewski, Maciej
Pluciński, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/174254.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
light scattering
Monte Carlo
numerical methods
Opis:
The light scattering process can be modeled mathematically using the Fredholm integral equation. This equation is usually solved after its discretization and transformation into the system of algebraic equations. Volume integral equations can be also solved without discretization using the Monte Carlo algorithm, but its application to the light scattering simulations has not been sufficiently studied. Here we present the implementation of this algorithm for one and three-dimensional light scattering computations and discuss its applicability in this field. We show that the Monte Carlo algorithm can provide valid and accurate results but, due to its convergence properties, it might be difficult to apply for problems with large volumes or refractive indices of scattering objects.
Źródło:
Optica Applicata; 2020, 50, 1; 17-35
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral analysis of dynamic laser speckle patterns by using a full-field temporal modulation method
Autorzy:
Dake, W
Chasteen, E
Onyeuku, C
Powiązania:
https://bibliotekanauki.pl/articles/174461.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
laser speckle
spectral analysis
light scattering
Opis:
We introduce an approach for analyzing the power spectrum of the time-varying intensity in the dynamic laser speckle patterns. The method is free from the limitation imposed by the Nyquist criterion on the minimum sampling rate. The temporal modulation shifts the intensity fluctuation spectrum by an amount that is equal to the modulation frequency. The subsequent integration of the intensity signal, performed at each detector pixel, acts effectively as a low-pass filter allowing the extraction of the spectral component at the modulation frequency. Within the speed range from 1 to 10 mm/s investigated in our experiment, the result demonstrates that the moving speed of the diffuse object can be determined with a good accuracy.
Źródło:
Optica Applicata; 2013, 43, 4; 871-882
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial light modulator design and generation of structured electromagnetic waves using digital light processors
Autorzy:
Yalcinkaya, F.
Koc, T.
Pala, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2172826.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
spatial light modulator
digital micro-mirror device
digital light processing
structured electromagnetic wave
orbital angular momentum
hologram
Opis:
Spatial light modulators (SLMs) are versatile devices used for optical studies. These instruments have a wide area of application in photonics. Additionally, SLMs have potential utility in different applications, such as biomedical applications, laser based surgery for precise cutting and as optical tweezers to separate cells in a petri container. However, the high cost of SLM devices prevents their widespread use in many areas, including industrial areas and scientific research laboratories. This paper demonstrates how to design a digital light processor (DLP) based low-cost SLM and describes how to obtain structured electromagnetic waves with the designed SLM. Therefore, this research was undertaken to design and produce a low-cost SLM device for optical applications. For this purpose, two prerequisites had to be fulfilled, the first was to use suitable components of a projection device with DLP-based digital micro-mirror device (DMD), and the second was to eliminate unnecessary SLM components from the system. Finally, holographic images reflected on the SLM screen were created by using Mathematica software program to change the amplitude and phase of the electromagnetic waves in order to obtain the structured electromagnetic waves.
Źródło:
Optica Applicata; 2022, 52, 3; 461--479
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Visualization of pathologic changes in liver tissue via polarized light
Autorzy:
Stoilova, Ani
Blagoeva, Blaga
Nazarova, Dimana
Stoykova, Elena
Berberova-Buhova, Nataliya
Nedelchev, Lian
Machikhin, Alexander
Powiązania:
https://bibliotekanauki.pl/articles/2172829.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
polarized light imaging
tissue polarimetry
liver tissue
Opis:
In this work, we applied two polarized light based approaches to visualize histological patterns of liver pathologies. The first one involves acquisition of two images through a polarizing microscope, one image (Ppar) acquired with the analyzer oriented parallel to the polarization of illumination and the other (Pper) acquired with the analyzer oriented perpendicular to the illumination. The final image is based on the polarization ratio, Preconstructed = (Ppar – Pper)/(Ppar + Pper). Using the second technique, the histological specimens were illuminated with a polarized laser beam with wavelength of 635 nm. Polarimetric parameters as azimuth, angle of ellipticity, degree of polarization and reflected power have been measured to quantify the change in the polarization state of the incident light after interaction with the sample of the healthy tissue and of the tissue with abnormal morphological changes.
Źródło:
Optica Applicata; 2022, 52, 3; 395--404
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure equation as novel strategy for optimum reflector design
Autorzy:
Ou, Chung-Jen
Powiązania:
https://bibliotekanauki.pl/articles/174423.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
illumination design
light-emitting diodes
structure equation
Opis:
The optimal use of energy resources is the central dogma for green technology and bio-optics. Reflectors provide a simple and fundamental structure for energy transport from a light emitting diode (LED) chip, and an appropriately designed reflector can reduce the fabrication cost of secondary optics for the LED. This paper demonstrates the role of three proposed reflector geometric factors in the two performance metrics – uniformity and collected energy (power), for designing LED reflectors. Through canonical factor analysis, a linear structure equation for LED reflector is suggested, and the methodology for designing the optimal shape is discussed. In addition, a generalized factor and a synthesis response are proposed for a more comprehensive investigation of optical performance. Results indicate a key parameter for balancing the optical performance, and the effects of various parameters and the trade-offs are revealed.
Źródło:
Optica Applicata; 2020, 50, 1; 95-110
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emission-intensity-enhanced GaN-based LED based on multilayer grating structures
Autorzy:
Li, Xin
Sun, Dejie
Han, Kun
Cao, Lijun
Guo, Shiliang
Li, Zhiquan
Powiązania:
https://bibliotekanauki.pl/articles/2033893.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
light-emitting diode
surface plasmon
grating
quantum well
Opis:
A novel surface-plasmon-enhanced GaN-LED is proposed to improve the emission efficiency of the traditional LED. The SiO2 film, Ag triangular structure and ITO film were coated on the rectangularly-patterned p-GaN layer sequentially, which can form the quasi-symmetrical waveguide structure to enhance the internal quantum efficiency and the light extraction efficiency. The COMSOL software is used to simulate the LED structure. The radiated powers, absorbed powers and distribution of electric field are obtained and analyzed. The results reveal that emission efficiency of the proposed GaN-LED can be greatly improved.
Źródło:
Optica Applicata; 2021, 51, 4; 529-540
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrashort pulse propagation recording by using the transmission-type light in flight holography
Autorzy:
Fan, Y.
Li, J.
Zheng, S.
Lu, X.
Zhong, X.
Powiązania:
https://bibliotekanauki.pl/articles/174016.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
light in flight
visualization of pulse propagation
holography
Opis:
In this paper, the distortion of the reconstructed images of the propagating light pulse in transmission light-in-flight holography recording was analyzed. Based on the analysis model, for recording the wavefront more accurately, the optimized selection of relevant parameters was made. Furthermore, a cylindrical lens was introduced to correct the image distortion. Additionally, the light-in-flight recording of the wavefront changing during propagation was simulated.
Źródło:
Optica Applicata; 2017, 47, 2; 283-294
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancing light harvesting of organic solar cells by using hybrid microlenses
Autorzy:
Xiao, X
Zhang, Z
Xie, S
Liu, Y
Hu, D
Du, J
Powiązania:
https://bibliotekanauki.pl/articles/174313.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
organic solar cells
hybrid microlens
light harvesting
achromatization
Opis:
Organic solar cells have drawn intense attentions in recent years due to their inherent advantages. But the relatively low power conversion efficiency is the main obstacle in the way of organic solar cell commercialization. One of the main reasons that limit the power conversion efficiency is the mismatch between electrical transmission properties and light absorption properties in an organic active layer. In this work, a highly efficient light trapping scheme with a hybrid microlens array is proposed to resolve this contradiction. This structure can achieve broadband absorption enhancement in the spectrum of interest by chromatic aberration correction and hole parameter adjustment. And the light trapping element can be separated from cells to avoid direct contact with an organic layer that may cause electrical defects. Moreover, it is also compatible with low cost manufacturing technologies.
Źródło:
Optica Applicata; 2015, 45, 1; 89-100
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel trapezoidal profile of optimized diffraction grating for light trapping in thin silicon solar cells
Autorzy:
Dehdast, M.
Bahrami, A.
Mohammadnejad, S.
Powiązania:
https://bibliotekanauki.pl/articles/174344.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
diffraction grating
light trapping
quantum efficiency
solar cell
Opis:
In this paper, we propose a new design and comprehensive optimization process for improving the diffraction gratings used as the back reflector of silicon solar cells. For this process, the optimum refractive index and its corresponding available material which can be used as the grating material has been chosen as 1.57 and SiO2, respectively. Also, all of geometric parameters which affect the performance of the grating, such as periodicity, height and depth of grating profiles have been studied and the appropriate values for each of them have been proposed. In order to optimize the profile of grating, a transition from triangular to rectangular structure has been considered and finally a specific trapezoidal profile has been chosen as the optimized grating back reflector which enhances the cell efficiency up to 6%. Simulation results show that the different grating profiles have the same duty cycle and therefore use the same amounts of materials.
Źródło:
Optica Applicata; 2017, 47, 1; 75-83
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The use of motion peculiarities of particles of the Rayleigh light scattering mechanism for defining the coherence properties of optical fields
Autorzy:
Zenkova, C
Soltys, I
Angelsky, P
Powiązania:
https://bibliotekanauki.pl/articles/173481.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
degree of coherence
nanoparticles
Poynting vector
light scattering
Opis:
The paper proposes an alternative possibility for using the motion dynamics of tested particles of the Rayleigh light-scattering mechanism for estimating the degree of coherence of mutually orthogonal fields. The velocity of nanoparticles motion in the inhomogeneous optical field is chosen as the measuring parameter for diagnostics. The direct connection between the velocity of nanoscale particle motion and the degree of coherence of interacting fields is analytically demonstrated.
Źródło:
Optica Applicata; 2013, 43, 2; s. 297-312
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double tunneling induced transparency in the asymmetry quantum dot molecules
Autorzy:
Yu, C.
Huang, H.
Zhang, L.
Xu, D.
Powiązania:
https://bibliotekanauki.pl/articles/173599.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quantum dot molecule
slow light
tunneling induced transparency
Opis:
Using the density matrix theory, we have studied the double tunneling induced transparency slow light in the double asymmetry quantum dot molecules. With applied electric field, double tunneling induced transparency occur in the same time. Four absorption peaks are found near the resonance energy level in the absorption spectrum and the absorption peak can be tuned by the applied electric field. The velocity and bandwidth of the multiple-windows slow light can also be controlled by the applied electric field. In our model, with Te =0.1meV, we can get about 0.001c and 20GHz bandwidth in each transparency window. Such a property may be applied in all optical buffers, optical switching and filter.
Źródło:
Optica Applicata; 2016, 46, 3; 473-481
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Miniaturized ultraviolet sources driven by dielectric barrier discharge and runaway electron preionized diffuse discharge
Autorzy:
Erofeev, M
Baksht, E
Tarasenko, V
Powiązania:
https://bibliotekanauki.pl/articles/173213.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
excilamps
light sources
plasma spectroscopy
runaway electron preionized diffuse discharge
Opis:
In this work we have studied the energy and spectral characteristics of miniaturized dielectric barrier discharge KrCl-, XeCl-, XeBr-, and Xe2-excilamps of various designs as well as short pulse point-like light sources based on runaway electron preionized diffuse discharge. The maximum ultraviolet power density was 20 mW/cm2, which is comparable with the densities of ordinary dielectric barrier discharge excilamps, whereas the maximum efficiencies of the excilamps were not greater than 2.5%. The causes for the low radiation efficiency of the compact dielectric barrier discharge driven excilamps were analyzed. It is found that at an electron concentration of ne > 1014 cm–3, the efficiency decreases due to enhanced quenching of excited atoms or molecules in dissociation by electron impact. The spectral characteristics of a runaway electron preionized diffuse discharge formed between two pointed electrodes in atmospheric pressure air in an inhomogeneous electric field at a gap shorter than 8 mm were investigated. It is shown that the radiation spectrum of the discharge consists of bands of the second positive nitrogen system, and as the discharge transforms to a spark, lines of the electrode material appear in the spectrum. At a gap of 0.5 mm, weak X-rays from the discharge gap were detected.
Źródło:
Optica Applicata; 2014, 44, 3; 475-487
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical self-phase modulation using a new photonic crystal coupled-cavity waveguide
Autorzy:
Bahadori-Haghighi, S
Ghayour, R
Powiązania:
https://bibliotekanauki.pl/articles/173977.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
photonic crystal
slow light
coupled-cavity waveguide
self-phase modulation
Opis:
In this paper, self-phase modulation of an optical pulse using a new photonic crystal coupled-cavity waveguide is simulated and analyzed. The structure of the new coupled-cavity waveguide is introduced and its advantage over the previous type of coupled-cavity waveguide is discussed. In order to obtain a high group index over a large bandwidth and benefit from the slow light phenomenon, the group index and group velocity dispersion parameter curves of the guided mode are calculated. Finally, the transient simulation of the structure is performed using a finite-difference time-domain method. The calculated required length of the coupled-cavity waveguide for a maximum phase shift of π is about 31 μm. Spectral broadening of the optical pulse as a result of self-phase modulation is also presented and discussed.
Źródło:
Optica Applicata; 2014, 44, 1; 29-38
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł

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