In this paper, we proposed a structure to realize an all-optical digital multiplexer. The proposed structure had two inputs, one control and one output port. Using the control port, one can decide which input port can be connected to the output port. The proposed structure consisted of two nonlinear photonic crystal ring resonators, L-shaped and T-shaped, and a straight waveguide. Total footprint and maximum delay time of the proposed structure were 479 μm2 and 3 ps, respectively.

An All-Optical Digital 2-to-1 Multiplexer Using Photonic Crystal-Based Nonlinear Ring Resonators

Optical logic devices are the inevitable need for the future all optical computing and data processing. In this paper we are going to design and propose an all optical half subtractor using photonic crystal structure. The proposed structure will be realized using both threshold switching and beam interference. Finite difference time domain method used for analyzing the proposed structure. The simulation results show that the contrast ratio for D and B ports are 8 dB and 12 dB respectively. Also the maximum the maximum rise and fall times are 1 ps and 0.6 ps respectively.

A novel proposal for all optical half-subtractor based on photonic crystals

Optical comparators can play crucial roles in the all-optical digital circuits required for optical calculation and optical processing. A typical digital comparator is a logic circuit that can compare two binary codes and show the results by activating one of its three output ports. In this paper, a photonic crystal (PhC)-based structure was proposed for designing a 1-bit all-optical comparator. The proposed structure was designed using nonlinear ring resonators inside PhCs. Optical intensity of ${1}\,\,{\rm W/}\unicode{x00B5} {{\rm m}^2}$1W/µm2 at the input ports is required for the proper operation of the proposed structure. For the final structure, the maximum rise time obtained was about 4 ps.

Application of photonic-crystal-based nonlinear ring resonators for realizing an all-optical comparator.

Photonic crystals are suitable structures for designing various types of optical logic circuits. In this paper, an all-optical comparator is designed and simulated using two-dimensional photonic crystals. A combination of linear and point defects has been used in the proposed structure. The small number of point defects and the use of simple linear defects make this comparator simple design. One of the important features of this comparator is that it uses two outputs to compare the input bits. A small structure is used for the proposed optical comparator. Also, this structure has a delay time of 0.07 ps, which is due to the very small size of the structure and the use of a small number of defects. The simulation results show that the bit rate for the proposed comparator is 3.33 Tb/s. Therefore, this structure can be suitable for use in high-speed logic circuits.

Ultra-compact terahertz all-optical logic comparator on GaAs photonic crystal platform

Optical encoders are one of the important optical logic devices required in optical communications and optical signal processing. In this paper, we proposed a novel structure for designing an all-optical 4-to-2 optical encoder based on photonic crystals. For this purpose, four photonic crystal-based ring resonators were located between the input and output ports which results in improved coupling efficiencies between input and output waveguide and reduced cross-reflection between the input ports. The central wavelength of the photonic crystal-based ring resonators is 1555 nm. However, due to its wide bandwidth the proposed structure can be used for a wide range of optical waves. In the proposed structure, the delay time and the ON/OFF contrast ratio are 1.8 ps and 9.2 dB, respectively. The other advantages of the proposed structure is that we did not use nonlinear materials in designing the proposed structure, so there is no need for high amount of optical intensities.

Amir Salimzadeh

Papers

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