A novel design for realizing all optical analog to digital converter will be proposed in this paper. The proposed structure consists of two main parts; a nonlinear 3-channel demultiplexer, followed by an optical coder. The nonlinear demultiplexer will be used to quantize the input analog signal according to its optical intensity and the coder will convert the quantized levels into 2-bit binary codes. The nonlinear demultiplexer will be realized using three nonlinear resonant cavities. At appropriate values of input signal optical intensity one of the cavities can drop the optical beam to its corresponding output port. The proposed structure is capable of supporting maximum sampling rate up to 52 GS/s and total footprint of the structure is about 924 µm2.

All optical 2-bit analog to digital converter using photonic crystal based cavities

In this study, an all optical 4-to-2 encoder have been proposed which has four input and three output ports. The proposed structure can generate a 2-bit binary code considering which input port is active. For realising the proposed structure first the authors proposed and designed a BUFFER and an OR gate. Then combined these basic gates to realise the proposed encoder. The maximum switching delay and footprint for the proposed structure are about 200 fs and 880 μm2, respectively.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-opt.2016.0022

Proposal for 4-to-2 optical encoder based on photonic crystals

The present study was designed and simulated for an all optical half-adder, based on 2D photonic crystals. The proposed structure in this work contains a hexagonal lattice. The main advantages of the proposed designation can be highlighted as its small sizing as well as simplicity. Furthermore, the other improvement of this half-adder can be regarded as providing proper distinct space in output between "0" and "1" as logical states. This improvement reduces the error in the identification of logical states (i.e., 0 and 1) at output. Because of the high photonic band gap for transverse electric (TE) polarization, the TE mode calculations are done to analyze the defected lines of light. The logical values of "0" and "1" were defined according to the amount of electrical field.

Design of an all optical half-adder based on 2D photonic crystals

All-optical NOR and NAND gates based on photonic crystal ring resonator

In this paper, we propose what we believe is a novel all-optical analog-to-digital converter (ADC) based on photonic crystals. The proposed structure is composed of a nonlinear triplexer and an optical coder. The nonlinear triplexer is for creating discrete levels in the continuous optical input signal, and the optical coder is for generating a 2-bit standard binary code out of the discrete levels coming from the nonlinear triplexer. Controlling the resonant mode of the resonant rings through optical intensity is the main objective and working mechanism of the proposed structure. The maximum delay time obtained for the proposed structure was about 5 ps and the total footprint is about 1520  μm2.

Ultra-fast analog-to-digital converter based on a nonlinear triplexer and an optical coder with a photonic crystal structure.

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.

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

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 2000 mW/μm 2 , and 150 mW/μm 2 , 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 1 nm redshift the center operating wavelength of SR filter is 125 mW/μm 2 (i.e. Δ n NL  = 0.005) and for DR is as low as 8 mW/μm 2 . 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.

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

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.

https://link.springer.com/content/pdf/10.1007%2Fs11107-016-0680-x.pdf

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

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

A novel scheme for implementation of all-optical NOT logic gate based on photonic crystal ring resonator has been proposed. Photonic crystal is comprised of two-dimensional square lattice of dielectric rods in air substrate. Indium phosphide with a refractive index of 3.1 is adopted as the material of the rods. The finite different time domain (FDTD) and plane wave Expansion (PWE) methods are used to analyze the behavior of the structure. The simulation results show that the contrast ratio is 10.97dB for NOT gate. Moreover, the operational wavelength of the input ports is 1.55µm. Since the structure has a simple geometric shape with clear operating principle, it is potentially applicable for photonic integrated circuits. DOI: http://dx.doi.org/10.11591/ijece.v3i4.2909 Full Text: PDF

/pdf/all-optical-not-logic-gate-based-on-photonic-crystals-50quiskogq.pdf

Majid Ghadrdan

Papers

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

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

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

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

All-Optical NOT Logic Gate Based on Photonic Crystals