Nonlinear Photonic Crystal Ring Resonators Research Articles

A novel proposal for all-optical decoder based on photonic crystals

In this paper, a new structure for all-optical 2-to-4 decoder is proposed which consists of six nonlinear photonic crystal ring resonators. The lattice constant of the main structure is a = 600 nm, and the refractive index and radii of rods are 3.1 and 0.2a, respectively. Simulation results have proved correct operation states of the decoder and numerical analysis is done in order to additional evaluation. The maximum and minimum power levels for logic 0 and 1 are $$0.1P_{\mathrm{in}}$$ and $$0.37P_{\mathrm{in}}$$ where $$P_{\mathrm{in}}$$ is input power. The maximum cross talk and insertion loss are calculated about −38 and −20 dB, respectively. Since the operation speed of the decoder is more than 160 GHz, it will be appropriate candidate for being employed in ultrahigh-speed optical communication systems.

Design and simulation of all optical decoder based on nonlinear PhCRRs

An all optical 2*4 decoder will be designed and proposed in this paper. Nonlinear photonic crystal ring resonators are used for realizing the proposed decoder. Nonlinear photonic crystal ring resonators will be achieved by introducing nonlinear rods made of doped glass around the core section of the resonator. In the proposed structure X and Y port was used to switch the optical beams coming from E between O0, O1, O2 and O3 output ports. The optical intensity required for performing the switching task is about 50W/μm2. The maximum switching frequency and the total footprint of the proposed are 10GHz, and 581μm2. Reduced input optical intensity and compactness are the main characteristics of the present work. Numerical methods such as plane wave expansion and finite difference time domain were used for performing the required calculations.

An all optical 8 to 3 encoder based on photonic crystal OR-gate ring resonators

In this paper an 8 to 3 optical encoder will be proposed using nonlinear photonic crystal ring resonators. For realizing the proposed 8 to 3 encoder we will combine one optical waveguide with three 4-input port OR gates. In the proposed structure Ij (where j= 0, 1, 2, 3, 4, 5, 6 and 7), acts as input port. And O0, O1 and O2 act as the output ports, also V is auxiliary output port to distinguish the totally OFF state from the case in which I0 is ON. The maximum time delay of the proposed structure is about 2 ps.

Low-threshold ultrafast all-optical switch implemented with metallic nanoshells in the photonic crystal ring resonator

An all-optical switch based on nonlinear photonic crystal ring resonator embedded with silica dielectric surrounded by silver nanoshell (NS) inside the ring resonator has been introduced and analyzed in this article. We considered silica with radius of 10 nm and silver with radius of 16 nm as core and shell, respectively. By placing NSs inside the photonic crystal ring resonator, we succeeded in reducing the threshold power to 12.8 mW/μm2 and the switching time to about 0.4 ps. The results of this research suggest a new technique for reducing switching light intensity. With small size, ultra-fast switching time, and low-threshold power, the structure has the potential to be applied in optical integration circuits and nanoscale optical chips.

Application of photonic crystal ring resonator nonlinear response for full-optical tunable add–drop filtering

In this paper, we investigate the application of Kerr-like nonlinear photonic crystal (PhC) ring resonator (PCRR) for realizing a tunable full-optical add–drop filter. We used silicon (Si) nano-crystal as the nonlinear material in pillar-based square lattice of a 2DPhC. The nonlinear section of PCRR is studied under three different scenarios: (1) first only the inner rods of PCRR are made of nonlinear materials, (2) only outer rods of PCRR have nonlinear response, and (3) both of inner and outer rods are made of nonlinear material. The simulation results indicate that optical power required to switch the state of PCRR from turn-on to turn-off, for the nonlinearity applied to inner PCRR, is at least $$2000\, \hbox {mW}{/}\upmu \hbox {m}^{2}$$ and, for the nonlinearity applied to outer PCRR, is at least $$3000\, \hbox {mW}{/}\upmu \hbox {m}^{2}$$ which corresponds to refractive index change of $$\Delta n_\mathrm{NL }= 0.085$$ and $$\Delta n_\mathrm{NL }= 0.15$$ , respectively. For nonlinear tuning of add–drop filter, the minimum power required to 1 nm redshift the center operating wavelength $$(\lambda _{0} = 1550\, \hbox {nm})$$ for the inner PCRR scenario is $$125\, \hbox {mW}{/}\upmu \hbox {m}^{2}$$ (refractive index change of $$\Delta n_\mathrm{NL}= 0.005)$$ . Maximum allowed refractive index change for inner and outer scenarios before switch goes to saturation is $$\Delta n_\mathrm{NL }= 0.04$$ (maximum tune-ability 8 nm) and $$\Delta n_\mathrm{NL }= 0.012$$ (maximum tune-ability of 24 nm), respectively. Performance of add–drop filter is replicated by means of finite-difference time-domain method, and simulations displayed an ultra-compact size device with ultra-fast tune-ability speed.

All optical NAND gate based on nonlinear photonic crystal ring resonators

In this paper we proposed a new design for all optical NAND gate. By combining nonlinear Kerr effect with photonic crystal ring resonators first we designed AND and NOT gates, then by cascading these two structures we implemented a AND-NOT structure which operates as a NAND gate. The switching power threshold obtained for this structure equal to 1kW/μm2. For designing the proposed optical logic gate we employed two resonant rings with the same structures, both rings at the logic gates were designed such that their resonant wavelength be at λ=1550nm.

Full-optical tunable add/drop filter based on nonlinear photonic crystal ring resonators

Here, we propose a full-optical tunable Add/Drop filter based on single (SR) and double-vertically (DR) aligned Kerr-like nonlinear photonic crystal ring resonators (PCRRs). Silicon (Si) nano-crystal is used as the nonlinear material inside and outside of PCRRs. The minimum optical power required to turn–on/turn–off the SR and DR filters are 2000mW/μm2, and 150mW/μm2, respectively. We believe since the DR filter has a higher Q-factor rather than SR and also since the optical power reads more nonlinear rods with a longer time to pass the structure, thus the optical power required is much lower (10 folds). In addition, the minimum power required to 1nm redshift the center operating wavelength of SR filter is 125mW/μm2 (i.e. ΔnNL=0.005) and for DR is as low as 8mW/μm2. Performance of the Add/Drop filter structure is simulated by means of finite difference time domain (FDTD) method, in which the simulations showed an ultra-compact size structure with promising ultrafast tune-ability speeds.

All optical NAND gate based on nonlinear photonic crystal ring resonator

In this paper we proposed a new design for all optical NAND gate. By combining nonlinear Kerr effect with photonic crystal ring resonators, we designed an all optical NAND gate. A typical NAND gate is a logic device with one bias and two logic input and one output ports. It has four different combinations for its logic input ports. The output port of the NAND gate is OFF, when both logic ports are ON, otherwise the output port will be ON. The switching power threshold obtained for this structure equals to 1.5kW/μm2. For designing the proposed optical logic gate we employed one resonant ring whose resonant wavelength is at 1554nm. The functionality of the proposed NAND gate depends on the operation of this resonant ring. When the power intensity of optical waves is less than the switching threshold the ring will couple optical waves into drop waveguide otherwise the optical waves will propagate on the bus waveguide.

Implementation of all-optical switch based on nonlinear photonic crystal ring resonator with embedding metallic nanowires in the ring resonators

A novel all-optical switch based on nonlinear photonic crystal ring resonator with embedding metallic nanowires in the ring resonators has been simulated and analyzed by the finite difference time domain method. We placed Ag-nanowires inside the ring resonator to reduce light intensity. The ring resonator has a low switching time of about 0.6 ps and low switching power equal to 36.5 mW/µm2. Since the structure is of small size and ultra-fast time, it has the potentiality to be applied in optical integration circuits and nano-plasmonic information processing.

Successive approximation-like 4-bit full-optical analog-to-digital converter based on Kerr-like nonlinear photonic crystal ring resonators

Implementing of photonic sampling and quantizing analog-to-digital converters (ADCs) enable us to extract a single binary word from optical signals without need for extra electronic assisting parts. This would enormously increase the sampling and quantizing time as well as decreasing the consumed power. To this end, based on the concept of successive approximation method, a 4-bit full-optical ADC that operates using the intensity-dependent Kerr-like nonlinearity in a two dimensional photonic crystal (2DPhC) platform is proposed. The Silicon (Si) nanocrystal is chosen because of the suitable nonlinear material characteristic. An optical limiter is used for the clamping and quantization of each successive levels that represent the ADC bits. In the proposal, an energy efficient optical ADC circuit is implemented by controlling the system parameters such as ring-to-waveguide coupling coefficients, the ring’s nonlinear refractive index, and the ring’s length. The performance of the ADC structure is verified by the simulation using finite difference time domain (FDTD) method.

All optical active high decoder using integrated 2D square lattice photonic crystals

The paper introduces a novel all optical active high 2 × 4 decoder based on 2D photonic crystals (PhC) of silicon rods with permittivity of ε = 10.1 × 10−11 farad/m. The main structure of optical decoder is designed using a combination of five nonlinear photonic crystal ring resonator, set of T-type waveguide, and line defect of Y and T branch splitters. The proposed structure has two logic input ports, four output ports, and one bias input port. The total size of the proposed 2 × 4 decoder is equal to 40 μm × 38 μm. The PhC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The overall design and the results are discussed through the realization and the numerically simulation to confirm its operation and feasibility.

All-optical S-R flip flop using 2-D photonic crystal

The photonic crystals (PhC) draw significant attention to build all optical logic devices and considered one of the solutions for the opto-electronic bottleneck via speed and size. The paper presents a novel all optical SR flip flop memory based on two optical NOR gates using 2D PhC. The design of optical Flip Flop is based on four nonlinear photonic crystal ring resonator and T-type waveguide. The total size of the proposed optical memory flip flop is equal to 30 μm × 30 μm. The structure has lattice constant ‘a’ is equal to 630 nm and bandgap range from 0.32 to 044. The flip flop design has a switching time in few Picoseconds and low power input of 50 mW. The PhC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The overall design and the results are discussed through the experimental implementation and the numerically simulation to confirm its operation and feasibility.

All optical NOR and NAND gate based on nonlinear photonic crystal ring resonators

In this paper we proposed optical NOR and NAND gates. By combining nonlinear Kerr effect with photonic crystal ring resonators first we designed a structure, whose optical behavior can be controlled via input power intensity. The switching power threshold obtained for this structure equal to 2kW/μm2. For designing the proposed optical logic gates we employed two resonant rings with the same structures, both rings at the logic gates were designed such that their resonant wavelength be at λ=1550nm. Every proposed logic gate has one bias and two logic input ports. We used plane wave expansion and finite difference time domain methods for analyzing the proposed structures.

Concurrent implementation of all-optical half-adder and AND & XOR logic gates based on nonlinear photonic crystal

A new design for concurrent implementation of all-optical half-adder and AND & XOR logic gates based on nonlinear photonic crystal ring resonator has been proposed. The finite different time domain and plane wave expansion methods are used to analyze the behavior of the structure. The ring resonator has a low switching time of about 0.85 ps and low switching power equal to \(277\,\text{ mW}/\upmu \text{m}^{2}\). The simulation results show that the contrast ratio is 12.78 dB for AND gate and 5.67 dB for XOR gate. Moreover, the operational wavelength of the input ports is \(1.55\,\upmu \text{m}\). Since the structure has a simple geometric shape with clear operating principle, it is potentially applicable for photonic integrated circuits.

Design of Optical Nor Logic Gates Using Two Dimension Photonic Crystals.

In this paper, a novel all-optical NOR logic gate based on two dimension (2-D) photonic crystals (PC) is designed and simulated by a cascade of two all-optical switches. The new all-optical switch is composed of a nonlinear photonic crystal ring resonator (PCRR) and T-type waveguide. The PC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The bandgap of this structure is derived by the plane wave expansion (PWE) method, which is from a/= 0.32 to a/= 0.44. In this structure to work at the wavelength of 1550 nm, the lattice constant ‘a’ should be 630 nm; the total size of the proposed optical NOR gate is only 18 m × 11 m. The simulation results using two dimensional finite difference time domain (FDTD) method indicated that the proposed optical NOR logic gate is a potential candidature for ultrafast optical digital circuits.

All-optical ultra-compact photonic crystal NOR gate based on nonlinear ring resonators

We have proposed an ultra-compact all-optical photonic crystal 'NOR' gate, based on two Kerr nonlinear photonic crystal ring resonators. This logic gate can operate with a bit rate of about 138.9 Gbit s−1. We have employed an Si nanocrystal as the nonlinear material for its appropriate nonlinear properties. The operational principle and properties of our proposed gate has been described by finite difference time domain and plane wave expansion methods.

All-optical ultracompact photonic crystal AND gate based on nonlinear ring resonators

We have proposed an ultracompact all-optical photonic crystal AND gate based on nonlinear ring resonators, consisting of two Kerr nonlinear photonic crystal ring resonators inserted between three parallel line defects. We have employed a Si nanocrystal as the nonlinear material for its appropriate nonlinear properties. The gate has been simulated and analyzed by finite difference time domain and plane wave expansion methods. The proposed logic gate can operate with a bit rate of about 120 Gbits/s.