All-optical Multiplexing Research Articles

Nanomaterials in Nanophotonics Structure for Performing All-Optical 2 × 1 Multiplexer Based on Elliptical IMI-Plasmonic Waveguides

In this study, an all-optical multiplexer (Mux) based on elliptical insulator-metal-insulator (IMI) plasmonic waveguides is designed. The area of the proposed structure is very small (400 nm × 400 nm) which operates at a wavelength of 1,550 nm. The developed device utilizes constructive and destructive interferences between the input signals and the selector signal. This structure is less complex and has lower loss compared to the previous works. Transmission (T), contrast ratio (CR), modulation depth (MD), insertion loss (IL), and contrast loss (CL) are the five parameters that describe the performance of the plasmonic Mux. The transmission threshold between logic 0 and logic 1 is 0.5. Moreover, the maximum transmission efficiency of the device is 163%. Moreover, based on the MD value of 95.09%, the dimensions of the proposed structure are excellent and optimal. The proposed plasmonic Mux structure contributes substantially to developing an all-optical arithmetic logic unit (ALU) and all-optical signal processing nanocircuits. The finite element method (FEM) simulates the proposed plasmonic multiplexer with COMSOL Multiphysics 5.4 software.

Compact and High-Speed All-Optical 2n:1 Multiplexer Scheme Using MRRs

The purpose of this research paper is to present a new all-optical scheme to implement the logical behavior of generalized [Formula: see text]th-order (2[Formula: see text]:1) multiplexer logic. The proposed all-optical design is based on micro-ring resonator (MRR)-based all-optical switches and constructed by using “2[Formula: see text]-2” MRR structures, arranged in a series “[Formula: see text]” stage architecture. The presented configuration enjoys advantageous features like compact-sized systematic structure and ultra-fast speed. To validate the logical behavior of the proposed [Formula: see text]th-order multiplexer, a second-order (22:1) multiplexer is derived (from the proposed scheme) and discussed. Further, the usability of the presented all-optical multiplexer is demonstrated by developing an all-optical reconfigurable logic gate that can be reconfigured to perform various logic operations. To verify the logical behavior of MRR-based all-optical switch and presented all-optical multiplexer logic, numerical simulations through MATLAB software have been performed. The reported reconfigurable logic structure is also simulated in the MATLAB environment to validate the desired behavior.

ALL-OPTICAL CARRY SKIP ADDER WITH THE HELP OF TERAHERTZ OPTICAL ASYMMETRIC DEMULTIPLEXER-BASED SWITCH

The terahertz optical asymmetric demultiplexer (TOAD) or semiconductor optical amplifier (SOA)-assisted Sagnac switches have been used to construct an all-optical 4-bit carry skip adder. This design aims to satisfy the high speed and accuracy requirements of modern ultrafast digital transmission. Using a combination of an all-optical multiplexer and an all-optical full adder, we describe an all-optical carry skip adder. When compared to ripple carry adder and carry look-ahead adder, carry skip adder may be employed to create a fast arithmetical processing unit. Numerical simulation is used to develop and validate this theoretical model.

Optical Multiplexer

In this paper, we present an all-optical multiplexer based on a Terahertz Optical Asymmetric Demultiplexer (TOAD) device. The TOAD is used as a nonlinear optical switch to selectively route optical signals based on their wavelength or frequency, allowing for the multiplexing of multiple optical channels onto a single fiber optic cable. We describe the design and implementation of the TOAD-based multiplexer, including the optical components and signal processing algorithms used to achieve high-speed, low-error-rate operation. We also present experimental results demonstrating the performance of the multiplexer, including its ability to maintain signal quality over long distances and under various noise and interference conditions. Our results show that the TOAD-based multiplexer offers a promising approach to all-optical multiplexing for high-speed, high-capacity optical communications systems.

Design and simulation of a 2 × 1 All-Optical multiplexer based on photonic crystals

Photonic crystals are alternating structures widely used to design various types of logic circuits. In this paper, a 2 × 1 multiplexer is designed and simulated based on two-dimensional photonic crystals with a cubic lattice. Silicon rods in the air were used to design this multiplexer. Only linear defects were considered in the design of the structure. In other words, none of the rods were changed and all Si rods were the same, which is one of the advantages of this structure. Optical sources with a wavelength of 1.55 µm were utilized in the inputs and select line. The size of the structure was 12.16 µm × 12.16 µm. The small dimension and the simplicity of the structure make it a suitable candidate in optically integrated circuits.

Realization of all-optical multiplexer–demultiplexer in mid-IR wavelengths using triple-core photonic quasi-crystal fiber

We report a wide bandwidth and low crosstalk Ge11.5As24Se64.5 triple-core photonic quasi-crystal fiber (TPQF) for the multiplexing–demultiplexing (MUX–DEMUX) operation in mid-IR region. In this numerical investigation, we explore the various MUX–DEMUX parameters such as coupling length, coupling length ratio, separation length, crosstalk and bandwidth. Further, the proposed TPQF based MUX–DEMUX exhibits high bandwidth of 263, 252, 214, 129 and 134 nm for low crosstalk of -36.47, -34, -31, -30 and -31.3 dB at the wavelengths of 2, 2.3, 2.9, 3.5 and 4μm, respectively. The proposed MUX–DEMUX characteristics are realized first time in TPQF at mid-IR wavelengths. Besides, the bandwidth is improved as 310, 292, 286, 148 and 164 nm for the very low crosstalk level of -45.8, -44, -42.3, -42.35 and -49.93 dB for the separation lengths of 5.5, 6.1, 6.6 and 7.4 mm wavelengths of 2/4-μm, 2.3/4-μm 2.9/4-μm and 3.5/4-μm, respectively, when phase of core 1 is about 1.2π. Thus, the proposed TPQF-based MUX–DEMUX is a suitable candidate for the development of mid-IR photonic devices such as wavelength division multiplexing (WDM) couplers and power splitters.

Method of implementation and application of all-optical frequency-encoded multiplexer and demultiplexer utilizing total reflectional switches (TRSs)

Method of implementation of all-optical multiplexer and demultiplexer is proposed. The basic element used in this proposal is a total internal reflectional switch based on nonlinear materials having negative nonlinear refractive index. As a suitable nonlinear material, polymer 4MBCU(poly[dodecadiyn-1,12-diol-bis(n-butoxycarbonyl-methyl-urethane)]) may be useful to implement these devices. The use of controlling light induces nonlinearity and the path of the input data beam is controlled. The select inputs are in frequency-encoded format and have several advantages. Both 1:4 and 1:9 demultiplexers and 4:1 and 9:1 multiplexers are proposed in frequency-encoded format. As an application, the demultiplexer is used to implement encoder for frequency-encoded decimal numbers. The devices proposed are truly all-optical and use no electronic components for its operation and hence can show ultra-high processing speed.

Full-field vibration profilometry using time-averaged interference microscopy aided by variational analysis.

Full-field vibration testing is indispensable in characterization of micro-electro-mechanical components. Time-averaged interference (TAI) microscopy is a very capable and accurate vibration profilometry technique. It employs natural all-optical multiplexing of required information, i.e., recorded interferogram is amplitude-modulated by the Bessel pattern, which in turn encodes spatial distribution of vibration amplitude in its underlying phase function. We propose a complete end-to-end numerical scheme for efficient and robust vibration amplitude map demodulation based on the variational data-analysis paradigm. First, interferogram is variationally pre-filtered and complex analytic-interferogram is generated, exploiting the Hilbert spiral transform. The amplitude term of analytic-interferogram is accessed for Besselogram, i.e., TAI amplitude modulation distribution. Next, the Besselogram is variationally pre-filtered and complex analytic-Besselogram is calculated applying the Hilbert spiral transform. Finally, the phase term of the analytic-Besselogram is determined, unwrapped and post-filtered to achieve spatial distribution of vibration amplitude. Proposed approach is verified using simulated interferograms and corroborated upon experimental vibration testing. Reported method compares favorably with the reference Hilbert-Huang transform-based method. The improvement was gained by adding two new steps to the calculation path: (1) additional removal of the interferogram's residual background and noise and (2) variational based vibration amplitude map error correction method.

Electromagnetically induced polarization grating

Based on electromagnetically induced transparency (EIT), we investigate an all-optical grating structure to realize polarization-dependent multiple beam splitting in the Raman-Nath limit. To optimize the grating performance, higher excited state [e.g., nS1/2 (n ≥ 6)] of ultracold 87Rb atoms is employed to construct a five-level Ξ-Λ system sharing one common populated ground state. A principal advantage of our proposed scheme is that the σ± components of a linearly polarized weak probe field can be decoupled and thus be independently diffracted with high efficiency in both one and two dimensions by exploiting different quasi-standing waves as the two strong coupling fields in the Ξ and Λ configurations. Such an all-optical polarization-sensitive operation could greatly enhance the tunability and capacity of all-optical multiplexing, interconnecting, and networking in free space for both classical and quantum applications.

All-optical Nyquist-OTDM to Nyquist-WDM conversion for high-granular flexible optical networks.

We have proposed and experimentally demonstrated all-optical multiplexing (MUX)-format conversion from Nyquist optical time division multiplex (OTDM) to Nyquist wavelength division multiplex (WDM). The system is simply configured with a straight-type phase modulator (PM) driven by a sinusoidal wave and an optical Nyquist filter. In the theoretical investigation, it is proved that the single Nyquist signal is completely converted to Nyquist WDM signal, which consists of two half-baud-rate signals with different carrier frequencies. The theoretical modulation voltage for the phase modulator is slightly lower than Vπ: 0.913 Vπ, and it is experimentally verified. In the experimental demonstrations, 50 Gbaud to 25 Gbaud x 2 and 25 Gbaud to 12.5 Gbaud x 2 conversions are successfully demonstrated with quite low optical signal-to-noise ratio (OSNR) penalties. In addition, cascaded MUX-format conversion is also demonstrated; 50 Gbaud Nyquist signal is converted to four channels of 12.5 Gbaud Nyquist signals.

A dual purpose, all optical multiplexer circuit in InP, for multiplexing clock and NRZ data, and for transmultiplexing WDM to TDM

We present a new, integrated all-optical multiplexer for wavelength grooming of many WDM channels into a single TDM channel. The chips were realized in a novel generic InP foundry process. For design and mask layout of the multiplexer circuits, we developed a simple equivalent circuit, representing the incorporated wavelength converter. With the chips realized, successful WDM to TDM transmultiplexing is demonstrated, as well as multiplexing of clock and NRZ data.

All-optical reconfigurable logic operations with the help of terahertz optical asymmetric demultiplexer

An all-optical reconfigurable logic operation essentially constitutes a key technology for avoiding complex and speed limited optoelectronics conversions and performing various processing tasks. All-optical reconfigurable logic operations with the help of terahertz optical asymmetric demultiplexer (TOAD) is proposed and described. The paper describes the all-optical reconfigurable logic operations using a set of all-optical multiplexer and optical switches. We have tried to exploit the advantages of TOAD-based switch to design an integrated all-optical circuit which can perform the different logic operations AND, XOR, NOR and NOT. Numerical simulation confirming described methods is given in this paper.

Gradient echo memory in a tripod-like dense atomic medium

We analyze the storage and retrieval of a weak light pulse, having two orthogonally (circularly) polarized components, onto an atomic ensemble of four-level atoms of the tripod type driven by a far detuned coupling field. The atoms are subject to a longitudinal magnetic field which produces a spatially varying Zeeman splitting of the lower levels along the medium and allows for a spatial encoding of the different angular frequencies of the input pulse during the storage phase. A single reversion of the external magnetic field results in a rephasing of the dipoles and leads to the release of the stored signals. The shape of the recovered pulse is a time-reversal copy of the input pulse. The application of an additional reversion of the magnetic field during the storage phase allows the release of a copy of the input pulse without time reversal. We also show that the system may operate like an all-optical multiplexer when considering two impinging optical fields which have orthogonal components. The proposal has potential applications in quantum information processing.

All-optical arithmetic unit with the help of terahertz-optical-asymmetric-demultiplexer-based tree architecture

An all-optical arithmetic unit with the help of terahertz-optical-asymmetric-demultiplexer (TOAD)-based tree architecture is proposed. We describe the all-optical arithmetic unit by using a set of all-optical multiplexer, all-optical full-adder, and optical switch. The all-optical arithmetic unit can be used to perform a fast central processor unit using optical hardware components. We have tried to exploit the advantages of both optical tree architecture and TOAD-based switch to design an integrated all-optical circuit that can perform binary addition, addition with carry, subtract with borrow, subtract (2's complement), double, increment, decrement, and transfer operations.

WDM to OTDM multiplexing using an ultrafast all-optical wavelength converter

A robust and scalable all-optical multiplexer combining four 10-Gb/s WDM channels into one 40-Gb/s OTDM channel is presented. The multiplexer generates a coherent output data stream, which does not suffer from channel interference as passively generated OTDM data do.

NONLINEAR DIRECTIONAL COUPLERS IN AlGaAs

In this paper we review the progress made in implementing nonlinear directional couplers as potential all-optical switching devices. We will discuss the operation of the coupler and its application as an all-optical multiplexing, demultiplexing element and consider the possibility of integrating more than one nonlinear switching element. The limitation of dispersion and nonlinear absorption will also be addressed.

All-optical multiplexing of femtosecond signalsusing an AlGaAsnonlinear directional coupler

The authors demonstrate multiplexing of femtosecond signals without the usual 3 dB loss of conventional passive multiplexers using an AlGaAs nonlinear directional coupler controlled by strong pump pulses.

All optical signal regularizing/regeneration using a nonlinear fiber Sagnac interferometer switch with signal-clock walk-off

All-optical signal regularizing/regeneration using a nonlinear fiber Sagnac interferometer switch (NSIS) that employs signal-clock walk-off is investigated. The NSIS realizes all-optical signal regeneration, including timing and amplitude regularizing, by switching clock pulses with amplified input signals using a walk-off-induced, wide, square switching window and intensity-dependent transmittance of the device. First, characteristics (in both the temporal and spectral domains) of the all-optical signal regeneration achieved with the NSIS are investigated theoretically and experimentally. They certify that if clock pulses are within the square switching window obtained with signal-clock walk-off, the clock pulses can be modulated according to the data that the input signals carry and retain their temporal and spectral profiles. This means that if clock pulses can be prepared that meet the system requirements, the NSIS can convert input signals that may not satisfy system requirements into high-quality output signals. Limitations on the switching contrast due to the cross-phase modulation of counterpropagating reference pulses is also discussed. Second, two possible applications of NSIS-based all-optical signal regularizing/regeneration, 1) an all-optical multiplexer with an optical clock and 2) an all-optical regenerative repeater, are discussed. Preliminary experiments with /spl sim/10-ps pulses at bit rates of /spl sim/5 Gb/s that use locally prepared optical clock pulses, show that the NSIS provides an error-free regeneration function with a certain tolerance for pulse-period irregularity if a proper optical clock is obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>