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Analysis and simulation of a channel add-drop filter composed of two dimensional photonic crystal
Abstract
In this paper, the properties of the resonant modes in the two dimensional (2-D) photonic crystal (PC) cavities and channel add-drop filters have been presented. Both square and triangular PC lattices have been analyzed. We have used an effective numerical method based on the finite-difference time-domain (FDTD) scheme for computing resonant modes. We have clarified coupling between the single point cavity and a line defect waveguide as a channel add-drop filter.
... Since the defect involves removing dielectric material of the crystal, the effective refractive index of the cavity decreases and the mode moves towards the higher edge of the gap [13,14]. In linear state, by increasing the refractive index of all rods of the structure to 3.54, similar to nonlinear state, the incident light cannot couple to the cavity at f = 0.3816(c/a). ...
In this paper, the performance of an all optical switch based on two dimensional (2-D) nonlinear photonic crystal (PC) microcavities has been demonstrated. We have used an effective numerical method based on the finite-difference time-domain (FDTD) method. It has been shown that by increasing the input signal power the refractive indices of the rods besides the waveguide are changed, due to the nonlinear Kerr effect. Therefore, the resonant frequency of the cavity shifts to a lower value, compared to that of the linear case. The performance of the switch in linear and nonlinear states for various radii of the microcavity and different distances from the waveguide have been simulated and analyzed. The distributions of the electromagnetic fields have been illustrated. The nonlinear resonant frequency of the cavity and the refractive index variations of the rods due to the Kerr nonlinearity have been derived.
Based on effects of lateral coupling between the resonant L3 cavity and tow quasi waveguides bends in tow dimensional photonic crystal (2D PhC) who depends strongly on the parameters of geometry of the PC lattice, especially on the dielectric rods sizes. We proposed Photonic Crystal BandPass Filter (PCBPF), the out put transmission spectra of our filter covered three band. Band I covers the wavelength range from 1.331 to 1.355 μm has 86% of transmission power, Band II, from 1.390 to 1.427 μm, has 98% of the transmission power and Band III from 1.46 to 1.507 μm, has 27% of the transmission power. The full width at half maximum bandwidth of these bands is 9.7, 13.1 and 16.4 nm, respectively. This Filter (PCBPF) is proposed for photonic integrated circuits (PIC), wavelength division multiplexing (WDM) systems and sensing applications. The normalized transmissions spectra of this filter are obtained them using 2D Finite Difference Time Domain Method (2D-FDTD). The Photonic Band Gap is calculated by Plane Wave Expansion method (PWE).
We propose a wide angle, efficient and low loss 1 × 3 power splitter based on triangular lattice air holes silicon slab Photonic Crystal (PhC). Desired power splitting ratio was achieved by altering the structure at the junction area of the power splitter. Simulation results obtained using 2-D finite difference time domain method show that for TE polarization incident signal, the power is distributed almost equally with total normalized transmission of 99.74% and negligible reflection loss at the 1550 nm optical operating wavelength. In addition, the power splitter can operate at 1388 nm and 1470 nm optical wavelengths.
The properties of rod-type and hole-type 2-D photonic crystal structures are investigated in detail in order to characterize their parameters and suitability in all-optical switching applications and as miniature integrated optical components. The optimum material and structural parameters are reported for controlling the position and width of band gap in various configuration, and design guidelines are discussed.
We demonstrate the capabilities of principal component analysis (PCA) for studying the results of finite-difference time-domain (FDTD) algorithms in simulating photonic crystal microcavities. The spatial-temporal structures provided by PCA are related to the actual electric field vibrating inside the photonic microcavity. A detailed analysis of the results has made it possible to compute the phase maps for each mode of the arrangement at their respective resonant frequencies. The existence of standing wave behavior is revealed by this analysis. In spite of this, some numerical artifacts induced by FDTD algorithms have been clearly detailed through PCA analysis. The data we have analyzed are a given set of maps of the electric field recorded during the simulation.
A novel three-port channel add/drop filter consisting of two waveguides and two cavities is proposed. One is used for a resonant tunneling-based channel add/drop operation from the bus waveguide to the add/drop waveguide, while the other is used to realize the wavelength-selective reflection feedback in the bus waveguide. By means of coupled mode theory in time, the conditions to achieve 100% add efficiency are derived thoroughly. Based on these theoretical analysis, the channel add filter and some other multi-channel filters are designed in two-dimensional photonic crystals (2D PCs) with square lattice of dielectric rods in air. The numerical results by using the finite-difference time-domain (FDTD) method demonstrate almost complete channel add/drop tunneling at resonance via the three-port systems.
This paper describes a theoretical and experimental analysis of the channel drop filter using a single defect formed near the two-dimensional (2-D) photonic crystal slab waveguide. First, we calculate the transmission spectrum of a 2-D photonic crystal waveguide and show that high transmittance for a wide wavelength range (∼60 nm) is obtained in the 1.55-μm region. We also show that a defect state having a wavelength within the high transmission wavelength range can be formed in the photonic bandgap by introducing a single defect of appropriate radius. Next, we fabricate several devices and show that the emission wavelength from each defect can be tuned by changing the defect radius. The measured tuning characteristics coincide well with the calculated results. From the near-field pattern of the device, we estimate the emission efficiency of the present device at almost a few tens percent. We clarify the structural condition in order to obtain the maximum output efficiency and show that tuning of emission wavelength while maintaining high output efficiency is possible by selecting appropriate defect radius and position. Based on these results, we propose an ultrasmall channel drop filter for a wavelength-division-multiplex optical communication system.
IEEE J. Lightwave Technol.
- M Imada
- S Noda
- A Chutinan
- M Mochizuki
- T Tanaka