Performance Analysis of Three-Wavelength Multi-Channel Photonic Crystal Filters of Different Sizes

Multi-wavelength and multi-channel photonic crystal filters are designed with different sizes considered by using a two-dimensional quadric lattice photonic crystal structure to solve the problems of a multi-channel filter with structure complexity, single-wavelength download, and channel interference. The designed filter consists of a waveguide, reflection wall, multimode microcavity, and output port. Each port can download three different wavelengths. In the communication band from 1.500 to 1.600 μm, the transmittance of each channel is greater than 90%, and the filtering efficiency is high. The size of the non-simplified filter is only 27 μm × 17 μm. On the premise of ensuring low loss transmittance (that is, the transmittance of each port is changed by no more than 10% at the wavelength from 1.5–1.6 μm), the size of the filter can reach 15 μm × 7 μm. This design will greatly reduce the overall structure size of the filter and is suitable for multiplexing and demultiplexing in WDM systems.

Multi-Rate Filter Banks

This chapter presents the theoretical description and the principle of the operation of analysis and synthesis filter banks. This is essential material for understanding the modern design of transceivers that are based on discrete-time signal processing. The structure of a quadrature mirror filter bank is presented and the operation of the analysis and synthesis component filters is explained. The condition for a perfect reconstruction of a two-channel filter bank is derived. Based on a two-channel quadrature mirror filter bank, the procedure of making a multichannel quadrature mirror filter bank is presented. A brief description of multilevel filter banks with equal or unequal passband widths is given.

A Plasmonic Infrared Multiple-Channel Filter Based on Gold Composite Nanocavities Metasurface

A plasmonic near-infrared multiple-channel filter is numerically and experimentally investigated based on a gold periodic composite nanocavities metasurface. By the interference among different excited plasmonic modes on the metasurface, the multipeak extraordinary optical transmission (EOT) phenomenon is induced and utilized to realize multiple-channel filtering. Investigated from the simulated transmission spectrum of the metasurface, the positions and intensity of transmission peaks are tuned by the geometrical parameters of the metasurface and environmental refractive index. The fabricated metasurface approached transmission peaks at 1128 nm, 1245 nm, and 1362 nm, functioning as a three-passbands filter. With advantages of brief single-layer fabrication and multi-frequency selectivity, the proposed plasmonic filter has potential possibilities of integration in nano-photonic switching, detecting and biological sensing systems.

A Step-by-Step Approach to Bandpass/Channel Filter Design

This paper presents a step-by-step approach to the design of bandpass/channel filters. The chapter serves as a reference source to microwave stakeholders with little or no filter design experience. It should help them design and implement their first filter device using the microstrip technology. A 3-pole Chebyshev bandpass filter (BPF) with centre frequency of 2.6 GHz, fractional bandwidth of 3%, passband ripple of 0.04321 dB, and return loss of 20 dB has been designed, implemented, and simulated. The designed filter implementation is based on the Rogers RT/Duroid 6010LM substrate with a 10.7 dielectric constant and 1.27 mm thickness. The circuit model and microstrip layout results of the BPF are presented and show good agreement. The microstrip layout simulation results show that a less than 1.8 dB minimum insertion loss and a greater than 25 dB in-band return loss were achieved. The overall device size of the BPF is 18.0 mm by 10.7 mm, which is equivalent to 0.16λg x 0.09λg, where λg is the guided wavelength of the 50 Ohm microstrip line at the filter centre frequency.

Optical detection of values of separate aberrations using a multi-channel filter matched with phase Zernike functions

The use of a multichannel wavefront sensor matched with phase Zernike functions to determine the type and magnitude of aberration in the analyzed wavefront is investigated. The approach is based on stepwise compensation of wavefront aberrations based on a dynamically tunable spatial light modulator. As criteria for successful detection, not only the magnitude of the correlation peak, but also the maximum intensity, compactness, and orientation of the distribution in each diffraction order are considered. On the basis of numerical simulation, the efficiency of the proposed approach is shown for detecting both weak and strong (up to a wavelength) wavefront aberrations.

Optical detection of values of separate aberrations using a multi-channel filter matched with phase Zernike functions

The use of a multichannel wavefront sensor matched with phase Zernike functions to determine the type and magnitude of aberration in the analyzed wavefront is investigated. The approach is based on stepwise compensation of wavefront aberrations based on a dynamically tunable spatial light modulator. As criteria for successful detection, not only the magnitude of the correlation peak, but also the maximum intensity, compactness, and orientation of the distribution in each diffraction order are considered. On the basis of numerical simulation, the efficiency of the proposed approach is shown for detecting both weak and strong (up to a wavelength) wavefront aberrations.