Optical Demultiplexer Research Articles

Designing of Polarization Encoded All-Optical Ternary Multiplexer and Demultiplexer

The advantages of Multi-valued logic (MVL) systems and circuits have drawn a significant interest as a coming generation technology that can be viewed as an alternative approach to solve many problems in transmission, storage and processing of large amount of information in digital signal processing. The paper presents an all-optical circuit for designing ternary (three-valued) multiplexer & demultiplexer with the help of polarization encoded basic ternary logic gates (ternary min and ternary delta literal). It focuses on recent patents / publications in relevant field and future scope of works in the fascinating field of optical multi-valued logic. Keywords: Optical logic, nonlinear optics, optical multi-valued logic, polarization, ternary multiplexer/demultiplexer, Multiplexer, Demultiplexer, Quantum Electronics, Solid-State circuits, optical processors, spatial light modulator, Terahertz Optical Asymmetric Demultiplexer, broadband communications, digital signals, digital communication system

Investigation of optical clock division and demultiplexing based on a commercial lithium niobate‐intensity modulator

AbstractWe demonstrate and investigate a simple technique to realize multichannel optical clock division by using a commercial lithium niobate‐intensity modulator (LN‐IM). Optical clock division is achieved by controlling the driving and dc bias voltage of the LN‐IM. 20‐ to 10‐GHz optical clock division experiments of both single and double channel are implemented to verify the performance of the proposed optical clock divider. The phase noise of the extracted 10‐GHz optical clock is less than 95 dBc/Hz. The other function of this technique, demultiplexing of optical time division multiplexing (OTDM) signal is also demonstrated experimentally. The 20‐Gb/s PRBS OTDM signal is successfully demultiplexed to two 10 Gb/s with high quality. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:94–99, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26477

Dual-carrier IQ modulator with a complementary frequency shifter

We devised a dual-carrier IQ modulator consisting of a novel complementary frequency shifter (CFS) and two IQ modulators. The CFS generates two optical subcarriers from a single light source and outputs them from separate ports without using any optical demultiplexing filters. We fabricated the modulator in a hybrid configuration of silica planar lightwave circuits and a LiNbO(3) phase-modulator array. Frequency-spacing-tunable operation of the CFS was demonstrated. With the modulator, we successfully generated a 100-Gb/s/pol dual-carrier OFDM-QPSK signal.

Proposed Architecture for MIMO Optical Demultiplexing Using Photonic Integration

This paper proposes and simulates a novel structure for optical demultiplexing of optical multiple-input-multiple-output (MIMO) systems. Such a structure obviates the need for electronic digital signal processing in low-dispersion links, potentially saving significant power consumption. It has the minimum number of required analog control elements for nonunitary MIMO demultiplexing.

Simultaneous Clock Enhancing and Demultiplexing for 160-Gb/s OTDM Signal Using Two Bidirectionally Operated Electroabsorption Modulators

We demonstrate a technique for performing optical time-division simultaneous clock enhancing and demultiplexing using two bidirectionally operated electroabsorption modulators (EAMs). The performance of the proposed setup is verified experimentally in a 160-Gb/s 100-km transmission system. The 10-GHz clock component is enhanced before launching into the clock recovery module. The recovered 10-GHz clock signal is featured with low timing jitter ( <;300 fs) and error-free transmission is achieved with the power penalty of ~ 0.9 dB. The proposed setup has merits of simultaneously enhancing base clock component and demultiplexing.

All-optical routing and space demultiplexer via four-wave mixing spatial splitting

We demonstrate the spatial splitting of the four-wave mixing beams and probe beams induced by the dressing fields. Such a splitting effect depends on frequency detuning, the intensities and the polarization states of the dressing beams. Our observations agree quite well with the theoretical results. In the experiments, we demonstrated the ability to realize space demultiplexer and router via splitting one spot to multiple spots. This demonstration of all-optically controlled routing has opened the door to the potential achievement of hyper-THz all optical router and space demultiplexer.

Performance of Optical Wavelength Demultiplexer Based on Silicon-on-Insulator (SOI) Microring Resonators (MRRs)

In this paper, we presented the performance analysis of Silicon- on- Insulator (SOI) based, four channels optical wavelength demultiplexer using microrings. The characterizations are done employing Finite- Difference Time- Domain (FDTD) mode simulations from RSOFT. Serially cascaded microring arrays up to the third order are demonstrated to discuss the design issues of the laterally coupled wavelength demultiplexer. Characteristics like the Free Spectral Range (FSR), crosstalk and insertion loss losses are studied.

All-optical cross-bar network architecture using TOAD based interferometric switch and designing of reconfigurable logic unit

The design of all-optical 2 × 2 Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch is proposed and described in this manuscript. Numerical simulation has been done to achieve the performance of the switch. Using this 2 × 2 TOAD based switch, cross-bar network architecture is designed. A reconfigurable logic unit is also proposed in this manuscript, which can perform 16-Boolean logical operations.

Semiconductor Device as Optical Demultiplexer for Short Range Optical Communications

In this paper we present results on the use of a multilayered a-SiC:H heterostructure as a wavelength-division demultiplexing device for the visible light spectrum. The proposed device is composed of two stacked p-i-n photodiodes with intrinsic absorber regions adjusted to short and long wavelength absorption and carrier collection. An optoelectronic characterisation of the device was performed in the visible spectrum. Demonstration of the device functionality for WDM applications was done with three different input channels covering the long, the medium and the short wavelengths in the visible range. The recovery of the input channels is explained using the photo-current spectral dependence on the applied voltage. An electrical model of the WDM device is proposed and supported by the solution of the respective circuit equations. Short range optical communications constitute the major application field, however other applications are also foreseen.

All-optical carry lookahead adder with the help of terahertz optical asymmetric demultiplexer

An all-optical model of carry lookahead adder (CLA) implemented with a semiconductor optical amplifier (SOA)-assisted Sagnac interferometer (TOAD) is presented. The model accounts for the SOA small signal gain, linewidth enhancement factor, the switching pulses energy and width and the Sagnac loop asymmetry. Adder is a very basic component in a central processing unit. The CLA is the highest speed adder nowadays. Theoritical model is presented and verified through numerical simulation. The method promises both higher processing speed and accuracy. The model can be enhanced the functionality in which carry lookahead adder is the basic building block.

All-optical pseudorandom binary sequence generator with TOAD-based D flip-flops

An all-optical pseudo random binary sequence (PRBS) generator is designed using serially interconnected discrete Terahertz Optical Asymmetric Demultiplexer (TOAD)-based D flip-flops in a configuration exactly like the standard electronic setup. The performance of the circuit is evaluated through numerical simulation, which confirms its feasibility in terms of the choice of the critical parameters. The proposed scheme has been theoretically demonstrated for a 3-bit and 7-bit degree PRBS but can be extended to higher order by means of additional TOAD-based D flip-flops. Thus it can constitute an efficient solution for implementing all-optically a PRBS in an affordable, controllable and realistic manner.

Single Harmonically Driven Electroabsorption Modulator for OTDM Demultiplexing

Optical demultiplexing from 160 Gbit/s to 10 Gbit/s in a single lumped, electrically driven electroabsorption modulator (EAM) is experimentally presented. A quantum-dash Fabry-Pèrot mode-locked-laser is used to sub-harmonically extract a clock signal from the 160 Gbit/s data stream. A drive signal consisting of a series of harmonics of the recovered clock signal enables error-free demultiplexing of all channels in a 160 Gbit/s single-polarization optical time division multiplexing (OTDM) signal. This technique is quasi-analytically compared with the conventional approach of cascading two EAMs when performing 160 Gbit/s to 10 Gbit/s demultiplexing. The analysis reveals that using a single, harmonically driven EAM can result in lower penalties with respect to both degradations of the extinction ratio and width of pulses used in the OTDM signal.

Crosstalk due to optical demultiplexing in subcarrier multiplexed systems

We report an in-depth investigation of the inter-modulation crosstalk in subcarrier multiplexing (SCM) systems with optical demultiplexing (ODeMux). Both theoretical derivations and numerical simulations show that the crosstalk in ODeMux systems mainly comes from the nonlinear mixing of the baseband and subcarrier modulations inside the signal channels. Several key parameters are then studied to estimate their effects on the magnitude of the crosstalk. As a result, performance optimization strategies are proposed for ODeMux SCM systems. In order to further enhance the transmission performance of ODeMux SCM systems, we discuss two techniques to suppress the inter-modulation crosstalk and analyze their effectiveness with numerical simulations.

Wavelength demultiplexing structure based on arrayed plasmonic slot cavities

A compact wavelength demultiplexing structure based on arrayed metal-insulator-metal (MIM) slot cavities is proposed and demonstrated numerically. The structure consists of a bus waveguide perpendicularly coupled with a series of slot cavities, each of which captures SPPs at the resonance frequency from the bus waveguide and tunes the transmission wavelength by changing its geometrical parameters. A cavity theory model is used to design the operating wavelengths of the structure. Moreover, single band transmission of each channel and the adjustable transmission bandwidth can be obtained by altering the drop waveguide positions and the coupling distance. The proposed arrayed slot cavity-based structure could be utilized to develop ultracompact optical wavelength demultiplexing device for large-scale photonic integration.

Optical demultiplexer device operating in the visible spectrum

In this paper, we present results on the use of multilayered a-SiC:H heterostructures as a device for wavelength-division demultiplexing of optical signals. These devices are useful in optical communications applications that use the wavelength division multiplexing technique to encode multiple signals into the same transmission medium. The device is composed of two stacked p–i–n photodiodes, both optimized for the selective collection of photo generated carriers. Band gap engineering was used to adjust the photogeneration and recombination rate profiles of the intrinsic absorber regions of each photodiode to short and long wavelength absorption in the visible spectrum. The photocurrent signal using different input optical channels was analyzed at reverse and forward bias and under steady state illumination. A demux algorithm based on the voltage controlled sensitivity of the device was proposed and tested. An electrical model of the WDM device is presented and supported by the solution of the respective circuit equations.

Optical orthogonal frequency division multiplexing demultiplexer using slab star coupler-based optical discrete Fourier transform circuit

We demonstrate an optical orthogonal frequency division multiplexing (OFDM) demultiplexer with an optical discrete Fourier transform circuit fabricated using silica planar lightwave circuit technology. This compact device can process an arbitrary number of subcarriers. The operation of a ten-channel device is demonstrated by demultiplexing a 100 Gbit/s (10 subcarrier × 10 Gbits/s) OFDM signal. We also discuss a main factor affecting characteristics degradation of the device.

All-optical XOR gate with optical feedback using highly Ge-doped nonlinear fiber and a terahertz optical asymmetric demultiplexer

We experimentally demonstrate an all-optical exclusive-OR (XOR) gate with optical feedback using a highly Ge-doped nonlinear fiber. The XOR is achieved based on cross-polarization rotation in nonlinear fiber, while the optical feedback employs a terahertz optical asymmetric demultiplexer (TOAD). The TOAD simultaneously cleans up the XOR output and converts the wavelength of the feedback signal to allow proper feedback operation. The performance of the all-optical XOR gate with optical feedback is studied through both experimental and simulation analysis. An open eye diagram of the XOR output in feedback mode is obtained experimentally, and a correct logic operation in feedback mode is proved through simulation.

All-Optical Binary-Coded Decimal Adder with a Terahertz Optical Asymmetric Demultiplexer

In electronic computing systems, the binary-coded decimal (BCD) method encodes decimal numbers with each digit represented by its own four-bit binary sequence. The method allows easy conversion to decimal digits for printing or display and also offers rapid decimal calculations. A proposed all-optical BCD adder uses a terahertz optical asymmetric demultiplexer (TOAD) to perform BCD addition in all-optical domain.

All-optical prefix tree adder with the help of terahertz optical asymmetric demultiplexer

We propose and describe an all-optical prefix tree adder with the help of a terahertz optical asymmetric demultiplexer (TOAD) using a set of optical switches. The prefix tree adder is useful in compound adder implementation. It is preferred over the ripple carry adder and the carry lookahead adder. We also describe the principle and possibilities of the all-optical prefix tree adder. The theoretical model is presented and verified through numerical simulation. The new method promises higher processing speed and accuracy. The model can be extended for studying more complex all-optical circuits of enhanced functionality in which the prefix tree adder is the basic building block.

Interferometric switch based all optical scheme for conversion of binary number to its quaternary-signed digit form

Multi-valued logic (with radix>2) can be viewed as an alternative approach to solve many problems in transmission, storage and processing of large amount of information in digital signal processing. In arithmetical operation signed digit number is very essential for carry free computation. To achieve the parallelism in computation, a suitable number system and an efficient encoding/decoding scheme for handling the data are very much essential. In radix-4 system negative number is represented by quaternary-signed digit (QSD). In this study a conversion from 3-bit binary number (2's complement representation) to its equivalent single-digit QSD is reported. The technique for conversion of QSD to its binary equivalent form is also presented. All-optical circuits are designed with non-linear material-based interferometric switches such as terahertz optical asymmetric demultiplexer in optical tree architecture, where the numbers are represented by different discrete polarised state of light. Device-based simulation of the proposed optical circuit is used to verify the operation of the optical converter.