Performance evaluation of photonic crystal ring resonators based optical channel add-drop filters with the aid of whispering gallery modes and their Q-factor

Abstract

As a basic type of linear defects, the PhC ring resonators are considered the most fascinating elements to be used in photonics integrated circuits for applications such as dense wavelength division multiplexing and Optical filtering that are among the most important components of the telecommunication systems. This article proposes two different optical channel add-drop filters (CDFs) based on rod-type two-dimensional square-lattice all-circular photonic crystal ring resonator. In the studied ring-type PhC cavity, there are some modes that are analogous to whispering gallery (WG) modes. For the proposed all-circular PhC ring resonator, the WG-like mode with the azimuthal mode number m = 10, couples out from cavity to the drop waveguide. Although because of the absence of perfectly circular symmetry, these WG-like modes are not exactly degenerate but they form a close doublet. The normalized frequencies (a/λ) of the doublets of m = 10 are a/λ = 0.3684, and 0.3645 and their Q-factors are 1050, 866 respectively. By selecting appropriate coupling distance between the PhC ring resonator and side-coupled W 1 waveguide, the CDFs are formed. For a TM polarized Gaussian source, the drop efficiency of both filters is more than 99.8 % in the 1.535-1.625 μm wavelength interval. The photonic bandgap and the WG-like modes of the PhC ring resonator are calculated using the PWE method, and the Q-factor of modes and the transmission spectra of CDFs are calculated using 2D-FDTD method.

Stretchable photonic crystals with periodic cylinder shaped air holes for improving mechanochromic performance

“…The photonic band gap of the two dimensional photonic crystal with periodic cylinder shaped air holes non-closepacked in triangular lattice is shown in figure 1(g) which is calculated through FDTD method with filling factor of r/ a=0.25. The horizontal axis lists the points of the first Brillion zone which is the smallest periodical space of lattice and the vertical axis represents the normalized frequency ωa/ 2πc=a/λ, where ω is the angular frequency, a is the lattice constant, c is the speed of light in the free space and λ is the vacuum wavelength [56,57]. For the TE polarized incident plane wave, the photonic band gap is formed between frequency ranges of 0.3768 and 0.3988, and the width of normalized band gap is 0.022.…”

High data rate 4x2 photonic crystal encoder using irregular hexagon ring resonator

“…Optical communications are considered the best option for achieving these advancements. An optical communication network typically consists of various components, such as optical fibers [1], waveguides [2] [3], filters [4] [5] [6], demultiplexers [7]- [8], logic gates [9] [10] [11], adders [12] [13], decoders [14] [15], encoders [16] [17] [18], data converters [19]. Other components constitute a typical optical communication network.…”

A novel 2D-PhC based ring resonator design with flexible structural defects for CWDM applications

“…Substantial improvement has been made to optical filter based devices in the areas of compactness, high spectral selectivity, fast switching, and low-power switching [7]. A photonic crystal (PhC) with a photonic band gap is a capable candidate for constructing devices that can operate over a wide range of wavelengths [8]. Because of its compactness and flexible design parameters, nowadays realization of ring resonators using photonic crystal (PhC) structure has been gaining importance [9].…”