The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform

Mohd Zubir Mat Jafri - One of the best experts on this subject based on the ideXlab platform.

  • Graphene based multimode interference coupler as an optical refractive index sensor based on nonlinear Modal Propagation analysis
    Modeling Aspects in Optical Metrology VI, 2017
    Co-Authors: M. A. A. Hassim, Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    The objective of this study is to propose and introduce nonlinear Modal Propagation analysis (NMPA) method being a viable way to study the application of graphene based multimode interference (MMI) coupler as an optical refractive index sensor. The purpose of using graphene in this study is because of its high optical nonlinearity as well as having a small bandgap due to its thin layer. The graphene based sensor can be tuned for highest sensitivity in wavelength and refractive index to detect the clad material. Graphene will act as the core of the sensor which will be placed on top of the sample. The clad refractive index value can be obtained by observing and analyzing the change in the output facet intensity of the sensor. The result also shows that the sensor has high sensitivity due to the usage of graphene and nonlinear region.

  • An optimum multimode interference coupler as an all-optical switch based on nonlinear Modal Propagation analysis
    Optik, 2015
    Co-Authors: Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    Abstract This paper proposes the Modal Propagation analysis (MPA) as a desirable way to study the all-optical switch based on small dimension MMI coupler in nonlinear regime. The finite difference method as a rigorous numerical method applies to solve the nonlinear Modal equations and measure the Modal Propagation constant. The contrast ratio between ON and OFF outputs that is called switching performance gain (SPG) is used to optimize the switch via output width. The results show good efficiency in few micrometer of MMI length and sensitivity of SPG to output width as well as input intensity.

  • Eyes on the Sky: All-Optical Sensor Based on Nonlinear Modal Interferences
    2014
    Co-Authors: Mohd Zubir Mat Jafri, Mehdi Tajaldini
    Abstract:

    Abstract. In this study, we propose an all-optical sensor based on consideration nonlinear effects on Modal Propagation and output intensity. The sensor can be tuned to highest sensitivity in the refractive index ranges sufficient to detect protein-based molecules, other water- soluble chemical, and air-pollutions. The nonlinear regimes show the capability to operate on any choice of materials for ridge waveguide. Crystalline polydiacetylene has high third-order susceptibility, thus could be best candidature for core material.  This material in presence of nonlinear effect is studied in the multimode waveguide with NMPA method that promises to investigate the coupler in small lengths. The visible changes of field intensity at output facet in various surrounding layer refractive index show the high sensitivity to the refractive index of surrounding layer that is foundation of introducing a sensor. Also, the results show the high distinguished changes on Modal Propagation in various refractive index of surrounding layer. To the best of our knowledge this is the first time that a nonlinear MMI in a few micrometers is proposed as a robustness sensor. In fact, this paper brings a useful and powerful way to progress the all optical sensors based on MMI couplers. Keywords: MMI, NMPA, all-optical sensor, mode, waveguides.

  • An ultra-compact multimode interference coupler as an optimum all-optical switch based on nonlinear Modal Propagation analysis
    Optics Communications, 2014
    Co-Authors: Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    Abstract This paper proposes Modal Propagation analysis (MPA) as an advantageous approach to studying an all-optical switch based on a small-dimension multimode interference (MMI) coupler at the threshold of the nonlinear regime. The finite-difference method is applied as a rigorous numerical method of solving the nonlinear Modal equations and measuring the Modal Propagation constant. The characterizations of two initial modes demonstrate the changes that are induced by nonlinear effects, such as the conversion of a sinusoidal profile to a Gaussian profile in the direction of Propagation, the high oscillation of the induced phase, and a variable shift in wavelength. Furthermore, all of the abovementioned changes manifest differently for each mode. The Gaussian profiles of guided modes accompanied by other observed phenomena lead to more efficient interferences among the modes to demonstrate switching applications at a small MMI length scale. The procedure for designing an optimum switch requires the implementation of a series of several studies of the switching operation based on related parameters, such as the contrast ratio between the ON and OFF outputs, which is called the switching performance gain (SPG); this parameter is used to optimize the switch via the output width, and the insertion loss is used in the same manner. The results indicate the efficiency of the approach at an MMI length of a few micrometers and indicate that SPG is sensitive to both output width and input intensity. To our knowledge, this is the first study to demonstrate power switching using nonlinear Modal Propagation analysis in the low-intensity nonlinear regime in a configuration created by guided-mode interferences.

  • IEEM - Self-focusing appearance in ultra-compact 3×3 multimode interference coupler based on silicon on insulator
    2014 IEEE International Conference on Industrial Engineering and Engineering Management, 2014
    Co-Authors: Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    The study of multimode interference (MMI) couplers in silicon waveguides is limited by the high index contrast, especially when operated in nonlinear regime. In low index contrast, the common method is beam Propagation method (BPM) that is based on several algorithms which propose a simple numerical method, but, in nonlinear high index contrast, the Modal Propagation analysis based on finite difference method (FDM) is a rigorous method, and high index contrast is a super benefit to confine the wave in waveguide in the maximum rate to appearance the self-focusing in highly ultra-compact size. In this paper, we investigate the nonlinear effect in high index contrast structure of silicon on insulator (SIO) 3×3 multimode coupler. Moreover, by simulation of the wave Propagation while the input intensities are increasing simultaneously, the appearance of self-focusing are demonstrated. The results show capability of nonlinear Modal Propagation by FDM numerical solution. Wave Propagation in multimode region accomplished with the output electric field indicate the good efficiency for the considered purposes.

Mehdi Tajaldini - One of the best experts on this subject based on the ideXlab platform.

  • Graphene based multimode interference coupler as an optical refractive index sensor based on nonlinear Modal Propagation analysis
    Modeling Aspects in Optical Metrology VI, 2017
    Co-Authors: M. A. A. Hassim, Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    The objective of this study is to propose and introduce nonlinear Modal Propagation analysis (NMPA) method being a viable way to study the application of graphene based multimode interference (MMI) coupler as an optical refractive index sensor. The purpose of using graphene in this study is because of its high optical nonlinearity as well as having a small bandgap due to its thin layer. The graphene based sensor can be tuned for highest sensitivity in wavelength and refractive index to detect the clad material. Graphene will act as the core of the sensor which will be placed on top of the sample. The clad refractive index value can be obtained by observing and analyzing the change in the output facet intensity of the sensor. The result also shows that the sensor has high sensitivity due to the usage of graphene and nonlinear region.

  • An optimum multimode interference coupler as an all-optical switch based on nonlinear Modal Propagation analysis
    Optik, 2015
    Co-Authors: Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    Abstract This paper proposes the Modal Propagation analysis (MPA) as a desirable way to study the all-optical switch based on small dimension MMI coupler in nonlinear regime. The finite difference method as a rigorous numerical method applies to solve the nonlinear Modal equations and measure the Modal Propagation constant. The contrast ratio between ON and OFF outputs that is called switching performance gain (SPG) is used to optimize the switch via output width. The results show good efficiency in few micrometer of MMI length and sensitivity of SPG to output width as well as input intensity.

  • Eyes on the Sky: All-Optical Sensor Based on Nonlinear Modal Interferences
    2014
    Co-Authors: Mohd Zubir Mat Jafri, Mehdi Tajaldini
    Abstract:

    Abstract. In this study, we propose an all-optical sensor based on consideration nonlinear effects on Modal Propagation and output intensity. The sensor can be tuned to highest sensitivity in the refractive index ranges sufficient to detect protein-based molecules, other water- soluble chemical, and air-pollutions. The nonlinear regimes show the capability to operate on any choice of materials for ridge waveguide. Crystalline polydiacetylene has high third-order susceptibility, thus could be best candidature for core material.  This material in presence of nonlinear effect is studied in the multimode waveguide with NMPA method that promises to investigate the coupler in small lengths. The visible changes of field intensity at output facet in various surrounding layer refractive index show the high sensitivity to the refractive index of surrounding layer that is foundation of introducing a sensor. Also, the results show the high distinguished changes on Modal Propagation in various refractive index of surrounding layer. To the best of our knowledge this is the first time that a nonlinear MMI in a few micrometers is proposed as a robustness sensor. In fact, this paper brings a useful and powerful way to progress the all optical sensors based on MMI couplers. Keywords: MMI, NMPA, all-optical sensor, mode, waveguides.

  • An ultra-compact multimode interference coupler as an optimum all-optical switch based on nonlinear Modal Propagation analysis
    Optics Communications, 2014
    Co-Authors: Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    Abstract This paper proposes Modal Propagation analysis (MPA) as an advantageous approach to studying an all-optical switch based on a small-dimension multimode interference (MMI) coupler at the threshold of the nonlinear regime. The finite-difference method is applied as a rigorous numerical method of solving the nonlinear Modal equations and measuring the Modal Propagation constant. The characterizations of two initial modes demonstrate the changes that are induced by nonlinear effects, such as the conversion of a sinusoidal profile to a Gaussian profile in the direction of Propagation, the high oscillation of the induced phase, and a variable shift in wavelength. Furthermore, all of the abovementioned changes manifest differently for each mode. The Gaussian profiles of guided modes accompanied by other observed phenomena lead to more efficient interferences among the modes to demonstrate switching applications at a small MMI length scale. The procedure for designing an optimum switch requires the implementation of a series of several studies of the switching operation based on related parameters, such as the contrast ratio between the ON and OFF outputs, which is called the switching performance gain (SPG); this parameter is used to optimize the switch via the output width, and the insertion loss is used in the same manner. The results indicate the efficiency of the approach at an MMI length of a few micrometers and indicate that SPG is sensitive to both output width and input intensity. To our knowledge, this is the first study to demonstrate power switching using nonlinear Modal Propagation analysis in the low-intensity nonlinear regime in a configuration created by guided-mode interferences.

  • IEEM - Self-focusing appearance in ultra-compact 3×3 multimode interference coupler based on silicon on insulator
    2014 IEEE International Conference on Industrial Engineering and Engineering Management, 2014
    Co-Authors: Mehdi Tajaldini, Mohd Zubir Mat Jafri
    Abstract:

    The study of multimode interference (MMI) couplers in silicon waveguides is limited by the high index contrast, especially when operated in nonlinear regime. In low index contrast, the common method is beam Propagation method (BPM) that is based on several algorithms which propose a simple numerical method, but, in nonlinear high index contrast, the Modal Propagation analysis based on finite difference method (FDM) is a rigorous method, and high index contrast is a super benefit to confine the wave in waveguide in the maximum rate to appearance the self-focusing in highly ultra-compact size. In this paper, we investigate the nonlinear effect in high index contrast structure of silicon on insulator (SIO) 3×3 multimode coupler. Moreover, by simulation of the wave Propagation while the input intensities are increasing simultaneously, the appearance of self-focusing are demonstrated. The results show capability of nonlinear Modal Propagation by FDM numerical solution. Wave Propagation in multimode region accomplished with the output electric field indicate the good efficiency for the considered purposes.

Kenneth T. V. Grattan - One of the best experts on this subject based on the ideXlab platform.

  • Spot-size transformations for laser-fiber integration
    Integrated Optic Devices II, 1998
    Co-Authors: B. M. A. Rahman, Muttukrishnan Rajarajan, Tiparatana Wongcharoen, Kenneth T. V. Grattan
    Abstract:

    In this paper several approaches to expand the field profile of a laser beam are studied. The power coupling efficiency and fiber coupling loss are discussed in detail. To achieve this, the rigorous vector finite element method is used to calculate the Modal Propagation properties and the least squares boundary residual method is employed to calculate the coupling loss, the reflection coefficient and the alignment tolerances of these devices.

  • Numerical study of spot-size expanders for an efficient OEIC to SMF coupling
    IEEE Photonics Technology Letters, 1998
    Co-Authors: Muttukrishnan Rajarajan, B. M. A. Rahman, Kenneth T. V. Grattan
    Abstract:

    Different types of spot-size converters are studied numerically, and their coupling loss and reflection properties are discussed in detail. The rigorous vector finite-element method is used to calculate the Modal Propagation properties and the least-squares boundary residual method is employed to calculate the coupling loss, reflection coefficient, and the alignment tolerances of the devices. It has also been observed that the reflection coefficient reaches a minimum when the mode confinement is at its maximum.

  • Accurate analysis of multimode interference devices
    IEEE Photonics Technology Letters, 1996
    Co-Authors: B. M. A. Rahman, Muttukrishnan Rajarajan, T. Wongcharoen, Kenneth T. V. Grattan
    Abstract:

    The accurate analysis of multimode interference devices is demonstrated by using the least-squares boundary residual (LSBR) method. Accurate Modal Propagation constants and spatial field profiles in the multimode interference (MMI) section can be obtained by using the finite-element method. The accurate calculation of the excited Modal coefficients is achieved by using the LSBR, which satisfies the continuity of the transverse field components more rigorously than the simple overlap integrals.

Ivana Gasulla - One of the best experts on this subject based on the ideXlab platform.

  • Few-mode fiber true time delay lines
    arXiv: Signal Processing, 2019
    Co-Authors: Sergi Garcia, Ruben Guillem, Ivana Gasulla
    Abstract:

    Space-division multiplexing optical fibers can provide not only parallel channel transmission but also parallel distributed signal processing, being this a feature particularly attractive in Microwave Photonics applications. We present here few-mode fiber links with tailored Modal Propagation and dispersion properties that operate as sampled true time delay lines for radiofrequency signals.

Sergi Garcia - One of the best experts on this subject based on the ideXlab platform.

  • Few-mode fiber true time delay lines
    arXiv: Signal Processing, 2019
    Co-Authors: Sergi Garcia, Ruben Guillem, Ivana Gasulla
    Abstract:

    Space-division multiplexing optical fibers can provide not only parallel channel transmission but also parallel distributed signal processing, being this a feature particularly attractive in Microwave Photonics applications. We present here few-mode fiber links with tailored Modal Propagation and dispersion properties that operate as sampled true time delay lines for radiofrequency signals.