Channel Drop Filter Research Articles

Realization of tunable optical filter by photonic crystal ring resonators

We have designed a tunable two dimensional (2D) channel drop filter (CDF) based on photonic crystal ring resonators (PCRR). Dropping efficiency and Q factor of single improved ring are 100% and 842, respectively. In this filter the quality factor is significantly improved with respect to other published reports. We investigate parameters which have an effect on resonant wavelength in this CDF, such as dielectric constant of inner, coupling, adjacent and whole rods of the structure and radius of inner rods. The transmission spectrum for our proposed configuration has been investigated using the 2D finite difference time domain (FDTD) method. The area of the proposed structure is about 117μm2.

Channel drop filter for CWDM systems

In this paper, a new design of channel drop filter (CDF) based on two-dimensional photonic crystal ring resonators (PCRRs) is provided by two-dimensional (2D) finite-difference time-domain (FDTD) simulations in triangular lattice photonic crystal (PC) silicon rods. 100% forward dropping efficiency and a quality factor of over 1000 can be achieved at maximum transfer efficiency while the operating wavelength is 1550nm. Through this novel component, three channel drop operation with 100% dropping efficiencies at all output channels can be obtained. The proposed filter provides a possibility of channel drop filter and could be used in coarse wavelength division multiplexing (CWDM) systems.

Channel-drop filter based on a photonic crystal ring resonator

In this paper combining a square lattice photonic crystal with a 12-fold quasicrystal, we proposed a new design for an optical channel-drop filter. Our proposed structure has a transmission efficiency very close to 1 and the band width and quality factor values for this structure are 4.5 nm and 344. After designing the channel-drop filter we investigated the effect of different parameters on the output wavelength of the filter. It has been shown that by changing the dielectric rods’ refractive index, radius of initial structure rods and the radius of the 12-fold quasicrystal rods we can obtain different output wavelengths of the filter.

Application of statistical method to investigate the effects of design parameters on the performance of microring resonator channel dropping filter

ABSTRACTMicroring resonator (MRR)‐based channel dropping filters have been extensively explored because of the high quality factor, compact size, and easy integration of fabrication. In order to design an excellent MRR wavelength filter, optimization of the design parameters are essential. In this paper, the design trade‐off of MRR‐based channel dropping filter was statistically studied by employing the Taguchi method. Four control factors considered were width of rings and channels, radii of the microring, upper rib waveguide height, and gap size. The analysis of variance was adopted to analyze significant trends that occurred on the free spectral range (FSR) and insertion loss (IL) performance under different sets of control factor combinations. The best parametric combination of control factors was identified in order to achieve a balance performance between large FSR and low IL using Finite‐Difference Time Domain (FDTD) simulation by RSoft Inc. After optimization, the value of FSR and IL obtained was 17 nm and 0.245 dB, respectively. Confirmation tests were carried out to verify the optimized parametric combinations and a new parametric combination considering both outputs were 16 nm and 0.215 dB. The optimal combinations were 6 µm ring radius with the separation gap of 50 nm and 350 nm × 350 nm rib waveguide cross section. Copyright © 2013 John Wiley & Sons, Ltd.

Ultra-Compact Photonic Circuit Components based on Propagation of Exciton Polaritons in Organic Dye Nanofibers

We fabricated a micron-sized ring resonator channel drop filter by micromanipulation of nanofibers of thiacyanine dye that propagate exciton polaritons along the fibers. The device consisted of a microring with a radius of r ≈ 4 μm and a straight nanofiber that functioned as an I/O bus channel. The performance of the device was evaluated using spatially resolved fluorescence microscopy. The device exhibited an extinction ratio of re = 2-4 dB for the visible wavelength region of 490-540 nm. Our results demonstrate that thiacyanine nanofibers are promising building blocks for exciton polariton-based photonic circuits, which can be highly miniaturized compared with conventional waveguide-based photonic circuits.

Ultracompact, Reflection-Free and High-Efficiency Channel Drop Filters Based on Photonic Crystal Nanobeam Cavities

We propose an ultracompact channel drop filter (CDF) based on photonic crystal nanobeam cavities. The conditions for implementing such an ideal CDF are derived from the temporal coupled-mode equations governing the operation of the CDF. By considering the intercoupling of the two involved nanobeam cavities, some ambiguities of the previous equivalent circuit model analysis are cleared up. Practical configurations on silicon-on-insulator (SOI) for the proposed CDF are suggested with a typical length less than 15 μm. Finite difference time domain (FDTD) method calculations show that the proposed filter can achieve drop efficiency higher than 99% without any reflection. Compared to the λ/4-shifted Bragg grating resonators based CDF, the proposed CDF is more compact, high-efficient and reflection-free. It is also easy to implement a low-power tunable filter due to the ultrahigh quality factor Q and ultrasmall modal volume V of the involved photonic crystal nanobeam cavities.

Analysis of a channel-drop filter based on dispersive waveguides and two resonant cavities

By use of coupled-mode theory we analyze a channel add–drop filter based on two dispersive waveguides symmetrically coupled with two resonant optical cavities. We show new solutions for the channel-drop filter processes compared to the solutions found by Manolatou et al (1999 IEEE J. Quantum Electron. 35 1322). For a special choice of the dispersion of the waveguides, we reveal a frequency region with sufficient total reflection.

Optical single sideband modulation of 60-GHz radio over fiber (ROF) system using ultra compact photonic crystal ring-shaped channel drop filter

An ultra compact photonic crystal (PC) ring-shaped channel drop filter (RSCDF) is proposed to generate single side band (SSB) signal for 60GHz ROF system. This PC-RSCDF contains a bus waveguide, a resonant cavity, a ring-shaped waveguide (RSW) and a coupled cavity output waveguide. The notch depth and notch bandwidth of CDF can get 98% and 0.4nm respectively by inducing RSW and shifting the center defect rod of cavity and the rod around the cavity. Then, a method of fine tuning the resonant frequency of PC-RSCDF is proposed by adjusting the radius of insensitive rods which have weak coupling interaction with the light and the sensitivity of structure can be decreased, and the resonant frequency can be shifted to the sideband frequency of double side band (DSB) signal accurately. Finally, a 60GHz ROF SSB modulation system is demonstrated by using designed PC-RSCDF that can filter lower or upper sideband by changing its structure parameters. The extinction ratio (ER) of lower and upper sideband can get 20.9dB and 18.6dB respectively.

Tunable Channel Drop Filter using Hexagonal Photonic Crystal Ring Resonators

In this paper, we have proposed a tunable two dimensional (2D) photonic crystal (PhC) channel drop filter (CDF) using ring resonators with suitable quality factor (Q) and transmission efficiency; we investigate parameters which have an effect on resonant wavelength in this CDF, such as dielectric constant of inner, coupling, adjacent and whole rods of the structure. Dropping efficiency at the resonance and quality factor of single ring are 90% and 1046, respectively. The footprint of the proposed structure is about 125.6μm 2 ; therefore this structure can be used in the future photonic integrated circuits. DOI: http://dx.doi.org/10.11591/telkomnika.v11i1.1788

Photonic crystal ring resonator channel drop filter

Photonic crystal channel drop filters (CDFs) with a ring resonator have been reported and have shown good optical properties to drop the light. Photonic crystal ring resonators (PCRRs) offer scalability in size and flexibility in mode design due to their multi-mode nature [1] compared to point-defect or line-defect photonic crystal (PhC) cavities. It is far smaller in size than other corresponding devices. In this paper, we proposed several channel drop filters combination of ring resonators and point defect micro-cavities. These ring resonators work as energy couplers. They capture the electromagnetic energy propagated in the input waveguide and send it to the output waveguide at its resonant frequencies. But ring resonators have too many resonant frequencies because of their multi-mode nature. So, point defect micro-cavities are used to further filter the original light wave. In our designed CDFs, close to 100% drop efficiency has been achieved at their center normalized frequencies, respectively.

Photonic crystal multi-channel drop filters with Fabry–Pérot microcavity reflection feedback

We have designed a multi-port channel-drop filter (MCDF) based on a two-dimensional photonic crystal (PhC) with a Fabry–Pérot reflector at the end of the bus waveguide. The conditions to achieve 100% drop efficiency at the resonance frequency were derived through the coupled mode theory in time and the transmission properties for such structure were calculated by finite-difference time-domain (FDTD) method. The results show that the light with different wavelengths can be successfully filtered to different ports by setting different radii of the center defect rods in the drop waveguides and high drop efficiency can be achieved by means of reflection feedback. The MCDF we designed can easily separate the light with five different wavelengths simultaneously with high drop efficiency. Among them are the wavelengths of 1.31 and 1.55μm which are two main communication wavelengths. It is superior than the MCDFs reported before and can be used extensively in optical communication systems.

Ultracompact Asymmetric Mach–Zehnder Interferometers with High Visibility Constructed from Exciton Polariton Waveguides of Organic Dye Nanofibers

AbstractManipulation of light using subwavelength waveguides is a key technology in the development of miniaturized photonic circuits, which possess various advantages over their electronic counterparts. The novel approach presented for such waveguiding involves the propagation of exciton polaritons (EPs), which are quasi‐particles formed by strong exciton–photon coupling, along organic dye nanofibers. A self‐assembled nanofiber of thiacyanine (TC) with a width of ≈200 nm propagates the EPs created by an optical excitation over a submillimeter‐scale distance and passes through a bend with a micrometer‐scale radius with low bending loss. To demonstrate the remarkable potential of EP‐based miniaturized photonic circuits, asymmetric Mach–Zehnder interferometers (AMZIs) are fabricated with TC nanofibers by micromanipulation. The AMZIs with a footprint of ≈20 μm × 20 μm exhibit a visibility of nearly unity and function as channel drop filters with the considerably high extinction ratio of up to ≈15 dB. Such high‐performance and ultracompact channel drop filters operating in the visible wavelength region have rarely been developed with other waveguide technologies. The coherent properties of the EPs in the nanofibers are investigated using time‐resolved experiments. The coherent properties provide useful information for designing EP‐based photonic circuits and for understanding EP dynamics in a nanofiber.

Photonic crystal higher order three-port channel drop filter

We present a photonic crystal (PC) three-port channel drop filter (CDF) with flat-top response and high quality factor value of 8836.7, and it can be used in the dense wavelength division multiplexing (DWDM) system. The CDF is engineered based on the three-port system with the wavelength-selective reflection feedback, where both micro-cavities are the synthesized coupled-resonators. In this case, the conditions to achieve complete power transfer are same to that of the corresponding three-port system while both micro-cavities are the single-mode resonators. As two micro-cavities are single point-defect resonators or synthesized coupled-resonators respectively, it is confirmed that these CDFs exhibit different response characteristics by the simulation results calculated by using two dimensional finite-difference time-domain (2D-FDTD) method, and these filters will find applications in future wavelength division multiplexing (WDM) optical communication systems.

Design and modeling of 2-D photonic crystals based hexagonal triple-nano-ring resonators as biosensors

Si photonic crystal resonator which comprises of three hexagonal nano-rings has been investigated. A forward-dropped peak at 1536.60 nm proves that the proposed triple nano-ring (TNR) resonator is a good channel drop filter, which makes it a good candidate for nanomechanical sensor applications. In this paper, the application of the TNR structure as a biosensor has been studied. It is realized that the symmetrical resonance output of the TNR resonator enhance its suitability as a biosensor as this characteristic makes sensing multiple biomolecules and corroboration of results at same input frequency possible.

Waveguide-coupled drop filters on SOI using quarter-wave shifted sidewalled grating resonators

We report on the design, fabrication, and demonstration of waveguide coupled channel drop filters at 1550 nm, on a silicon-on-insulator (SOI) substrate. These devices rely on resonant power transfer from a bus waveguide to side-walled Bragg resonators with quarter-wave shifts in the middle. By employing a second mirror resonator, and a tap-off waveguide, reflections along the bus waveguide can be reduced, leading to realization of circulator-free resonance filters. These devices were fabricated on SOI using e-beam lithography and inductively coupled plasma (ICP) etching. Fabricated devices with two coupled cavities are demonstrated to have rejection ratios greater than 20 dB and 3-dB bandwidths of 110 GHz, close to the values predicted by numerical modeling. We also demonstrate power tap-off at resonance of around 16 dB.

New design of channel drop filters based on photonic crystal ring resonators

In this paper, a new design of channel drop filters (CDFs) based on photonic crystals ring resonators (PCRRs) is presented. The filter characteristics for single-ring and dual-ring configurations based on two-dimensional (2D) triangular lattice photonic crystal (PC) silicon rods have been investigated by using the two-dimensional (2D) finite-difference time-domain (FDTD) method. Backward dropping efficiency of 96% and forward dropping efficiency up to 98% can be achieved in third communication window. Moreover, we investigate the dependence of resonant frequency on dielectric constant of whole rods of the structure as well as radius of the coupling rods. This device can be used as an optical channel drop filter (OCDF) in future communication applications.

Two bit all-optical analog-to-digital converter based on nonlinear Kerr effect in 2D photonic crystals

We have demonstrated the performance of a novel design for a single wavelength 2-bit all-optical analog-to-digital converter (ADC). This converter consists of two high efficient channel drop filters with a coupled cavity-based wavelength selective reflector in a 2D photonic crystal with total length of 15.87μm. The A/D conversion is achieved by using nonlinear Kerr effect in the cavities. The output ports switch to state ‘1’ at different input power levels to generate unique states preferred for an ADC. This conversion is simulated by the finite difference time domain (FDTD) method for 5 different power levels. The proposed structure can function as a two-bit ADC with a 60mW/μm input pulse and its maximum sampling rate is found to be ~45 GS/s.

Photonic Crystal Three-Port Channel Drop Filter Based on One-Way Waveguide

We design a highly efficient three-port channel drop filter (CDF) with only one channel drop micro-cavity based on photonic crystal (PC) one-way waveguide. According to the coupled mode theory in time, the conditions to achieve 100% drop efficiency are derived thoroughly. The numerical results are all calculated by using the finite element method, and accord well with the theoretical analysis. Compared with previous three-port CDF based on general dielectric PC, the CDF based on PC one-way waveguide first shows almost complete channel drop tunneling at resonance via only one channel drop micro-cavity without the need for any reflection feedback.

New Design of Channel Drop Filter by Triangular Photonic Crystal

We have designed a new type of optical channel drop filter (CDF) based on two dimensional triangular lattice photonic crystals. CDF operation is based on coupling to the photonic crystal waveguide. The proposed structure is optimized to work as a CDF. For obtaining the CDF characteristics and band structure of the filter, the finite difference time domain (FDTD) method and plane wave expansion (PWE) method are used respectively. Dropping efficiency at 1556 nm and quality factor ( Q ) of our proposed structure are 100% and 260, respectively. The quantities of quality factor and transmission efficiency are suitable for optical applications. The overall size of the proposed add drop filter is 191.97 µm 2 , which is smaller than the filters already reported and it is highly desirable for photonic integrated circuits (PICs). DOI: http://dx.doi.org/10.11591/ijece.v3i1.1931

Low-Voltage Widely Tunable Photonic Crystal Channel Drop Filter in SOI Wafer

We present the design, fabrication, and characterization of an electrostatically tunable optical channel drop filter based on 1-D photonic crystals (PCs) in silicon-on-insulator optical bench platform. Anisotropic etching of the device layer using deep reactive ion etching is used for the realization of the device. The moving parts are released by etching the buried oxide layer using wet etchants. High wavelength sensitivity of 9 nm/100 mV is achieved by moving the two constituent PCs together. Each PC half is moved by more than 250 nm on the application of 4 V effectively shrinking the cavity width by more than 500 nm. A wavelength tuning range of 70 nm with dropped channel bandwidth less than 8 nm in the 1550 nm–1620 nm wavelength range is demonstrated. <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hfill$</tex></formula> [2011-0183]