The Experts below are selected from a list of 7728 Experts worldwide ranked by ideXlab platform
Sourangsu Banerji - One of the best experts on this subject based on the ideXlab platform.
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To Study the Effect of Grating Length on Propagating Modes in Bragg Filters with AlXGa1-XN/GaN Material Composition
International Journal of Advanced Science and Technology, 2014Co-Authors: Sourangsu BanerjiAbstract:In this paper, the forward and backward propagating modes in an optical waveguide structure namely the fiber Bragg filter also considered as a one dimensional photonic crystal, is analytically computed as a function of Grating Length for coupled optical modes. AlxGa1xN/GaN material composition is considered as a unit block of the periodic organization, and refractive index of AlxGa1-xN/GaN is taken to be dependent on material composition, bandgap and operating waveLength following Adachi’s model. Expressions for propagating wave have been derived using coupled mode theory. Simulated results help us to study the propagation of forward and backward wave propagating modes inside fiber and waveguide devices.
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To Study the Effect of Grating Length on Propagating Modes in Bragg Filters with AlxGa1-xN/GaN Material Composition
arXiv: General Physics, 2013Co-Authors: Sourangsu BanerjiAbstract:In this paper, the forward and backward propagating modes in an optical waveguide structure namely the fiber Bragg filter also considered as a one dimensional photonic crystal, are analytically computed as a function of Grating Length for coupled optical modes. AlxGa1-xN/GaN material composition is considered as a unit block of the periodic organization, and refractive index of AlxGa1-xN/GaN is taken to be dependent on material composition, bandgap and operating waveLength following Adachi's model. Expressions of propagating wave are derived using coupled mode theory. Simulated results help us to study the propagation of forward and backward wave propagating modes inside fiber and waveguide devices.
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Study of Propagating Modes and Reflectivity in Bragg Filters with AlxGa1-xN/GaN Material Composition
arXiv: General Physics, 2013Co-Authors: Sourangsu BanerjiAbstract:In this paper, forward and backward propagating waves and reflectivity in an optical waveguide structure namely the fiber Bragg reflector also considered as a one dimensional photonic crystal, are analytically computed using coupled mode theory for different Grating Lengths and coupling conditions. AlxGa1-xN/GaN material composition is considered as unit block of the periodic organization, and refractive index of AlxGa1-xN is taken to be dependent on material composition, bandgap and operating waveLength following Adachis' model. The structure being considered is the Bragg Grating where increase in Grating Length enhances the reflection of electromagnetic wave, and strong coupling provides larger bandgap spectral width. Input waveLength is made different from Bragg waveLength to study the characteristics of propagating waves. A suitable combination of Grating Length and coupling coefficient is helpful in designing the photonic bandgap at 1550 nm waveLength. These characteristic curves can be utilized to study how waves propagate through the optical waveguides which have a special place in optical communications
Hsu-chih Cheng - One of the best experts on this subject based on the ideXlab platform.
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Fiber Bragg Grating complete parameter synthesis by using two thermally-modulated reflection intensity spectra and genetic algorithm
17th International Conference on Optical Fibre Sensors, 2005Co-Authors: Hsu-chih ChengAbstract:In this paper, we describe the use of a genetic algorithm and two thermally-modulated fiber Bragg Grating's (FBG's) reflection intensity spectra for inversely extracting complete physical parameters. The fiber Bragg Grating's complete parameters included the Grating period, Grating position, Grating Length, chirped direction, and refractive index modulation. In this study, a uniform and chirped fiber Bragg Gratings are synthesized successfully in the experiment. The experimental results show that the complete parameter synthesis in Grating period, Grating Length, refractive index modulation and various Grating positions from a 10 mm Length uniform FBG have been recovered accurately.
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Fiber Bragg Grating parameter estimation by using two thermally modulated intensity spectra for arbitrary distributed strain sensing
2005Co-Authors: Hsu-chih ChengAbstract:In this paper we describe the use of a genetic algorithm and two thermally-modulated fiber Bragg Grating's (FBG's) reflection intensity spectra for inversely extracting complete physical parameters. The fiber Bragg Grating’s complete parameters included the Grating period, Grating position, Grating Length, chirped direction, and refractive index modulation. In this study, a uniform and chirped fiber Bragg Gratings are synthesized successfully in the numerical analysis. Also, the experimental results show that the complete parameter synthesis in Grating period, Grating Length, refractive index modulation and various Grating positions from a 10 mm Length uniform FBG have been recovered accurately. After finding those physical parameters, the arbitrary distributed strain sensing technique is easy to accomplish by using two fiber Bragg Gratings sensing techniques.
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The synthesis of multiple parameters of arbitrary FBGs via a genetic algorithm and two thermally modulated intensity spectra
Journal of Lightwave Technology, 2005Co-Authors: Hsu-chih ChengAbstract:This paper describes the use of a genetic algorithm and two thermally modulated fiber Bragg Grating (FBG) reflection intensity spectra to perform the inverse extraction of multiple physical parameters of arbitrary FBGs, including the Grating period, Grating position, Grating Length, chirped direction, and refractive-index modulation. The developed numerical approach is applied to synthesize the parameters of uniform and chirped FBGs. The experimental results confirm the ability of the proposed method to recover the Grating period, Grating Length, Grating position, refractive-index modulation depth, and apodize factor of a 10-mm-Length uniform FBG. The proposed method is suitable for fiber communication applications and smart structure-monitoring systems.
Jose Azana - One of the best experts on this subject based on the ideXlab platform.
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Terahertz bandwidth all-optical Hilbert transformers based on long-period Gratings.
Optics Letters, 2012Co-Authors: Reza Ashrafi, Jose AzanaAbstract:A novel, all-optical design for implementing terahertz (THz) bandwidth real-time Hilbert transformers is proposed and numerically demonstrated. An all-optical Hilbert transformer can be implemented using a uniform-period long-period Grating (LPG) with a properly designed amplitude-only Grating apodization profile, incorporating a single π-phase shift in the middle of the Grating Length. The designed LPG-based Hilbert transformers can be practically implemented using either fiber-optic or integrated-waveguide technologies. As a generalization, photonic fractional Hilbert transformers are also designed based on the same optical platform. In this general case, the resulting LPGs have multiple π-phase shifts along the Grating Length. Our numerical simulations confirm that all-optical Hilbert transformers capable of processing arbitrary optical signals with bandwidths well in the THz range can be implemented using feasible fiber/waveguide LPG designs.
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all optical hilbert transformer based on a single phase shifted fiber bragg Grating design and analysis
Optics Letters, 2009Co-Authors: Mohammad H Asghari, Jose AzanaAbstract:A simple all-fiber design for implementing an all-optical temporal Hilbert transformer is proposed and numerically demonstrated. We show that an all-optical Hilbert transformer can be implemented using a uniform-period fiber Bragg Grating (FBG) with a properly designed amplitude-only Grating apodization profile incorporating a single π phase shift in the middle of the Grating Length. All-optical Hilbert transformers capable of processing arbitrary optical waveforms with bandwidths up to a few hundreds of gigahertz can be implemented using feasible FBGs.
Shivendu Prashar - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Grating Parameters Impact on Spectral Characteristics of LPFG using Two-Layer Fiber Geometry
2018 6th Edition of International Conference on Wireless Networks & Embedded Systems (WECON), 2018Co-Authors: Shivendu PrasharAbstract:The study on spectral characteristics of long period fiber Grating (LPFG) explores its usefulness in many applications. This scenario insists the researchers to calculate the impact of LPFG's parameters on its characteristics. The paper presents the effect of Grating Length and Grating period on the spectral characteristics of LPFG. Their impact is calculated in terms of variation in position of resonant waveLength and attenuation band depth. For this, the transmission profiles of LP03 and LP05 cladding modes are kept under observation here. The spectral profiles are calculated using analytical expressions obtained through coupled mode theory. The two layer fiber geometrical model is implemented on SMF28 optical fiber parameters to evaluate propagation constants of fiber's core region's and cladding region's modes. The results show linear increase in attenuation depth of spectrum with increase in Grating Length. On the other hand, with the rise in periodicity the shift in resonant waveLength is towards longer waveLengths.
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Investigative Study of Transmission Spectra of FBG at Varying Induced Index & Grating Length
Procedia Engineering, 2012Co-Authors: Shivendu Prashar, Derick Engles, Sham S. Malik, Rajan VohraAbstract:Abstract The waveLength tuning capacities of Fiber Bragg Gratings (FBG) are related with the change in reflectivity of FBG at Bragg's waveLength. There are two main methods to obtain such effect: by modifying the fiber refractive index or by changing the Grating period. In our work, we have simulated a uniform FBG in MATLAB and studied its transmission spectra for different refractive index modulation values at 0.5x10-4, 1.5x10-4and 2x10-4. The numerical integration of the coupled mode equation was used to solve the properties of FBG. Then a fast and accurate technique that based on T-matrix formalism was used for calculating the input and output fields. Reflectivity shown by FBG of Grating Length 7mm for different induced index values (Δn) = 0.5x10-4, 1.5x10-4and 2x10-4is 27.95%, 88.94% and 96.45% respectively. Reflectivity is also investigated for 10mm & 15mm Grating Lengths for the same values of Δn.
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investigative study of transmission spectra of fbg at varying induced index Grating Length
Procedia Engineering, 2012Co-Authors: Shivendu Prashar, Derick Engles, Sham S. Malik, Rajan VohraAbstract:Abstract The waveLength tuning capacities of Fiber Bragg Gratings (FBG) are related with the change in reflectivity of FBG at Bragg's waveLength. There are two main methods to obtain such effect: by modifying the fiber refractive index or by changing the Grating period. In our work, we have simulated a uniform FBG in MATLAB and studied its transmission spectra for different refractive index modulation values at 0.5x10-4, 1.5x10-4and 2x10-4. The numerical integration of the coupled mode equation was used to solve the properties of FBG. Then a fast and accurate technique that based on T-matrix formalism was used for calculating the input and output fields. Reflectivity shown by FBG of Grating Length 7mm for different induced index values (Δn) = 0.5x10-4, 1.5x10-4and 2x10-4is 27.95%, 88.94% and 96.45% respectively. Reflectivity is also investigated for 10mm & 15mm Grating Lengths for the same values of Δn.
Kristjan Leosson - One of the best experts on this subject based on the ideXlab platform.
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compact z add drop waveLength filters for long range surface plasmon polaritons
Optics Express, 2005Co-Authors: Alexandra Boltasseva, Sergey I Bozhevolnyi, Thomas Sondergaard, Thomas Nikolajsen, Kristjan LeossonAbstract:We design, fabricate and investigate compact Z-add-drop (ZAD) filters for long-range surface plasmon polaritons (LR-SPPs) at telecom waveLengths. The ZAD filter for LR-SPPs consists of two ridge Gratings formed by periodic gold thickness modulation at the intersections of three zigzag-crossed gold stripes embedded in polymer. We investigate influence of the Grating Length and crossing angle on the filter characteristics and demonstrate a 10°-ZAD filter based on 80-µm-long Gratings that exhibit a 15-dB dip (centered at ~1.55 µm) in transmission of the direct arm along with the corresponding ~13-nm-wide transmission peak in the drop arm.
