In this paper, a new structure for realizing a one-bit half-adder is proposed based on 2D photonic crystals. The proposed structure consists of 25 × 20 hexagonal lattice silicon rods in an ambient of air. The main advantages of this structure are a proper distinct space between “0” and “1” logical states of outputs, and smooth and stable outputs for a long time. These advantages are found to eliminate the error in identification of logical states (i.e., 0 and 1) at outputs. Working at a 1550-nm wavelength band (the most commonly used wavelength in optical communication known as third window), the simplicity of its structure and also integrable size has made this structure very efficacious for being realized as an all-optical logic gate.

A novel structure for realization of an all-optical, one-bit half-adder based on 2D photonic crystals

In this paper, the performance of various apodization profiles (uniform, hyperbolic tangent and gaussian) for un-chirped Fiber Bragg Grating is investigated. Apodization techniques are used to get optimized reflection spectra with high side lobe suppression. The simulations are done by solving coupled mode equations in MATLAB using transfer matrix method which explains the relationship between the guided modes. The result shows that Gaussian profile suppresses side lobe level much more efficiently than uniform and hyperbolic tangent profiles. Gaussian apodized Fiber Bragg Grating is used to indicate strain by producing wavelength shift. MATLAB and Opti-grating result gives an idea about the efficiency of the suggested scheme to analyze strain measurements by giving a linear response.

Simulation and analysis of Gaussian apodized fiber Bragg grating strain sensor

We propose and design a spiral photonic crystal fiber with elliptical air holes for achieving high birefringence, large nonlinearity, and negative dispersion. The structure is designed using chalcogenide glass (As2S3) for different ellipticity ratios of air holes in the cladding and the effect on various properties is observed. The proposed structure has birefringence of the order 10−2, nonlinearity of 26739.42 W−1 m−1, and dispersion of −1136.69 at 0.85 μm. An accurate numerical approach based on finite element method is used for the design and simulation of the structure. Due to high birefringence and negative dispersion, the proposed structure can be used for polarization control and dispersion compensation, respectively.

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Highly Nonlinear and Birefringent Spiral Photonic Crystal Fiber

This paper presents the modeling and characterization of an optical fiber grating for maximum reflectivity, minimum side lobe power wastage. Grating length and refractive index profile are the critical parameters in contributing to performance of fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths and different refractive index profiles. Apodization techniques are used to get optimized reflection spectra. The simulations are based on solving coupled mode equations by transfer matrix method that describes the interaction of guided modes.

Fiber Bragg Grating Modeling, Characterization and Optimization with different index profiles

Modeling and characterization of fiber Bragg grating for maximum reflectivity

The output of photonic integrated devices is enhanced using crystal waveguides and cavities but optimization of these devices is a topic of research. In this paper, optimization of the optical half adder in two-dimensional (2-D) linear photonic crystals using four symmetric T-shaped waveguides with 180° phase shift inputs is proposed. The input section of a T-waveguide acts as a beam splitter, and the output section acts as a power combiner. The constructive and destructive interference phenomenon will provide an output optical power. Output port Cout will receive in-phase power through the 180° phase shifter cavity designed near the junction. The optical half adder is modeled in a 2-D photonic crystal using the finite difference time domain method (FDTD). It consists of a cubic lattice with an array of 39 × 43 silicon rods of radius r 0.12 μm and 0.6 μm lattice constant a. The extinction ratio re of 11.67 dB and 12.51 dB are achieved at output ports using the RSoft FullWAVE-6.1 software package.

Modeling and Optimization of Optical Half Adder in Two Dimensional Photonic Crystals

In this paper an add/drop filter based on a two dimensional (2D) photonic crystal ring resonator (PCRR) is proposed and its performance is studied. This device is comprised of a hexagonal PCRR between two parallel waveguides formed by creating line defects in a 2D lattice structure with an array of 20 × 20 Si (Silicon) rods in air host. The lattice constant a is 636 nm and the radius of silicon (Si) rods r is 0.2a. The size of the add/drop filter is 6 μm × 6 μm. We have achieved nearer to 100% dropping efficiency when the wavelength (λ) of the optical input signal is 1.55 μm. Optical signal can be made to drop at a different port by varying its wavelength or radius of Si rods. Simulation of the device is performed using a licensed RSoft FullWAVE tool based on a finite difference time domain (FDTD) simulator. The proposed structure could be used as an add/drop filter in the wavelength division multiplexing.

Tunable Optical Add/Drop Filter for CWDM Systems Using Photonic Crystal Ring Resonator

Investigation of light behavior of all optical full adders in two‐dimensional photonic crystals

We present a numerical model and simulated results of fibre Bragg grating based WDM system. The proposed devices posses a significant improved wavelength conversion efficiency as compared to its AWG companion. Also, we present a FBG based dispersion comparator for an optical network. The device offers significantly improved bandwidth utilization and dispersion linearity over conventional designs. In our simulation, which took into account different sets of wavelength, the response of the device and dispersion compensation levels were studied. Also, we have shown a periodically modulated dispersion profile in the process of dispersion compensation.

Sanjaykumar C. Gowre

Papers

Modeling and Optimization of Optical Half Adder in Two Dimensional Photonic Crystals

Tunable Optical Add/Drop Filter for CWDM Systems Using Photonic Crystal Ring Resonator

Investigation of light behavior of all optical full adders in two‐dimensional photonic crystals

Numerical modeling and simulation of fibre-Bragg grating based devices for all-optical communication network

Dispersion characteristics of all-glass photonic crystal fibers