Semiconductor Optical Amplifier Mach-Zehnder Interferometer Research Articles

Efficient Reversible Multiplexer Design Using proposed AllOptical New Gate

The interest for transmission capacity in overall information systems keeps on expanding because of developing utilization of Internet and high-transfer speed applications, for example, video. All-optical signal processing is one promising system for giving the essential limit and offers payload transparency, power utilization which scales proficiently with expanding bit rates, lessened handling inertness, and ultrafast signal processing. These networks do not have any optical to electrical converters because signal is photonic throughout its path and thus energy is conserved which is otherwise wasted in conversion of photons to electrons and back. Thus to achieve this, various configurations of Mach-Zehnder Interferometers are used which make signal processing quite fast and also power consumption is reduced. For all-optical switching to become a reality, integration is necessary to significantly reduce the cost of manufacturing, installation, and operation. One promising integrated all-optical logic gate is the semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) which has advantages like faster switching time, ease of fabrication, lesser power and high speed. As transistor count is increasing day by day, power consumption is increased so it has put a limit on transistor count. Therefore reversible logic has come into picture which has remarkable property of dissipating lesser power. So digital circuits are designed with only consists of reversible logic gates and thus researchers are aiming at designing new gates to reduce the optical cost and delay of the circuits. In this paper a new gate has been proposed and multiplexer design is shown with improved optical cost and delay and also

WDM-Enabled Optical RAM at 5 Gb/s Using a Monolithic InP Flip-Flop Chip

We experimentally demonstrate an all-optical static random access memory (RAM) cell using a novel monolithic InP set-reset flip-flop (FF) chip and a single hybridly integrated semiconductor optical amplifier-Mach-Zehnder interferometer (SOA-MZI)-based access gate employing wavelength division multiplexing (WDM) data encoding. The FF device is a 6×2 mm 2 InP chip having a 97.8% reduced footprint compared with previous FF devices that were successfully employed in optical RAM setups. Successful and error-free RAM operation is demonstrated at 5 Gb/s for both read and write functionalities, having a power penalty of 4.6 dB for write and 0.5 dB for read operations. The theoretical potential of this memory architecture to allow RAM operation with memory speeds well beyond 40 GHz, in combination with continuously footprint-reducing techniques, could presumably lead to future high-speed all-optical RAM implementations that could potentially alleviate electronic memory bottlenecks and boost computer performance.

Design and analysis of various multifunctional operations at ultrahigh speed by using a semiconductor optical amplifier-Mach–Zehnder interferometer

Various multifunctional operations are performed by proposing designs of optical adder, subtractor, comparator, and decoder at 60 Gb/s. In all operations, constructive interference is produced by choosing optimized parameters, i.e., optical pulse generator power, input power, semiconductor optical amplifier-Mach–Zehnder interferometer parameters, and so on, for delivering a true output signal. An optical pulse-generated signal is required for all operations except addition, subtraction and equal to in a comparator.

Optical logic gates based on semiconductor optical amplifier Mach–Zehnder interferometer: design and simulation

All-optical logic gates are designed to extend the existing design to a higher number of bits, to use the same gate in multifunctions, and to add new gate designs. This type of gate is based on semiconductor optical amplifier (SOA) nonlinearities, since the SOA can provide a strong change of the refractive index together with high gain. The SOA is used with a Mach–Zehnder interferometer (MZI) forming an SOA-MZI structure which is used to perform the logic gates XOR, NOR, OR, and XNOR. Two binary input data signals are used with different number of bits (4, 6, 8, and 16 bit) at 10 Gbps. This work includes the study of the effect of the number of bits on the received power, minimum bit error rate, and maximum Q-factor.

Input-Power and Polarization Insensitive All-Optical Wavelength Converter With Monolithically Integrated Monitor PD and Gain-Controlled SOA

This paper presents a polarization-insensitive semiconductor optical amplifier Mach-Zehnder Interferometer (SOA-MZI) wavelength converter with a wide dynamic range. Direct detection of the wavelength-converted output signal power and feedback control of the signal power input to the SOA-MZI are proposed and are confirmed to be able to reduce the variation with input signal power and polarization. The gain-controlled SOA (GC-SOA) and monitor PD used to implement the feedback control are monolithically integrated into the SOA-MZI wavelength converter. A dynamic range of over 8 dB is obtained for TE and TM polarized input signals NRZ modulated at 43 Gb/s under feedback control, 7 dB better than with no feedback.

Generation of a 100‐GHz optical SSB signal using XPM‐based all‐optical frequency upconversion in an SOA‐MZI

ABSTRACTAn all‐optical single‐sideband (SSB) frequency upconversion technique using a semiconductor optical amplifier Mach–Zehnder interferometer with an interferometric configuration was demonstrated for radio‐over‐fiber applications. 99 and 101 GHz optical SSB signals, which showed no power fading associated with fiber dispersion for transmission over a single‐mode fiber with a length up to 20 km, were generated. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:35–38, 2015

A high performance all-optical set-reset flip-flop based on SOA-MZI

A set-reset all-optical flip-flop (SR-AOFF) based on semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is proposed. Simulation results show that low switching energy in the femto joule range, the transition time of less than 20 ps, high stability and high extinction ratio (ER) of 30 dB can be achieved, while AOFF output is power insensitive approximately.

Optical RAM Row Access With WDM-Enabled All-Passive Row/Column Decoders

In this letter, we present new architectural perspectives in optical static RAM configurations by exploiting the wavelength dimension in address domain. We present a 2 × 4 optical RAM row decoder (RD) that relies its operation on an all-passive wavelength-selective filtering matrix ( λ-matrix), receiving WDM-formatted address bits (Wordline) as input. The 2 × 4 RD is followed by an semiconductor optical amplifier Mach-Zehnder interferometer access gate and a column decoding unit to provide complete optical RAM row access. Proof-of-concept experimental verification of a 2 × 4 optical RAM RD is shown at 10 Gb/s, providing error-free operation with a peak power penalty lower than 0.2 dB.

Dual SOA-MZI Wavelength Converters Based on III-V Hybrid Integration on a $\mu{\rm m}$-Scale Si Platform

We report on the simultaneous wavelength conversion operation of a dual-element semiconductor optical amplifier-Mach–Zehnder interferometer (SOA-MZI) array hybridly integrated on a 4- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm m}$</tex> </formula> silicon-on-insulator (SOI) waveguide platform through thermocompression bonding. The SOAs are part of a six-element SOA array with both facets coupled on SOI through vertical and horizontal alignments. The device achieves almost two orders of magnitude reduction in footprint compared with state-of-the-art hybridly integrated SOA-MZI structures. We present for the first time experimental proof of the successful operation of a dual-element SOA-MZI device based on III-V technology on SoI that serves as a wavelength converter, with one SOA-MZI yielding error-free performance with a 0.8-dB power penalty at 12.5 Gb/s and the second SOA-MZI operating error-free at 10 Gb/s with a 2-dB power penalty.

Performance Analysis of a High-Speed All-Optical Subtractor using a Quantum-Dot Semiconductor Optical Amplifier-Based Mach-Zehnder Interferometer

This paper presents the simulation and design of an all-optical subtractor using a quantum-dot semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA MZI) structure consisting of two cascaded switches, the first of which produces the differential bit. Then the second switch produces the borrow bit by using the output of the first switch and the subtrahend data stream. Simulation results were obtained by solving the rate equations of the QD-SOA. The effects of QD-SOA length, peak power and current density have been investigated. The designed gate can operate at speeds of over 250 Gb/s. The simulation results demonstrate a high extinction ratio and a clear and wide-opening eye diagram.

A NEW STRUCTURE FOR ALL-OPTICAL THREE-INPUT XOR LOGIC GATE BASED ON SEMICONDUCTOR OPTICAL AMPLIFIER MACH–ZEHNDER INTERFEROMETER

In this paper the design and simulation of an all-optical three-input exclusive-OR (XOR) gate based on semiconductor optical amplifier-Mach–Zehnder interferometer (SOA-MZI) configuration is presented. This gate is constructed of three semiconductor optical amplifiers placed at the arms of the two coupled Mach–Zehnder interferometers. The outputs of these two MZIs are combined at the output port to form the final signal. The proposed scheme does not need a continuous wave (CW) laser for its operation and is designed so that the minimum number SOAs are employed. Theoretical analyses and simulations show that this structure acts as an all-optical three-input XOR logic gate which has many applications in optical data communications.

Down-Conversion Gain of an All-Optical SOA-MZI-Based Mixer Using Bandpass Sampling

The frequency conversion is one function of utmost importance in radio over fiber technologies. In this letter, we propose an optical implementation of a radio frequency down conversion based on a bandpass sampling technique realized by a semiconductor optical amplifier Mach-Zehnder interferometer used as an optical signal sampler. An optical pulse source generating 23-ps width pulses at a repetition rate of 7.8 GHz is employed to sample an intensity-modulated optical carrier carrying the signal to be frequency down converted. The frequency down conversion from a radio frequency signal at 37 GHz to an intermediate frequency at 2 GHz shows a positive conversion gain of 4 dB.

Optical Radiofrequency Signal Mixing by All-Optical Sampling Based on a Semiconductor Optical Amplifier Mach–Zehnder Interferometer

Experimental performances analysis of an optical radiofrequency signal mixer based on a semiconductor optical amplifier Mach-Zehnder Interferometer utilizing an all-optical sampling method is presented. An optical pulse source generating 21-ps width pulses at a repetition rate of 7.8 GHz samples an intensity-modulated optical carrier carrying an electrical subcarrier at the intermediate frequency 1 GHz. The efficiency of the all-optical radiofrequency mixer is evaluated in terms of mixing conversion gain and third-order input intercept point. The conversion gain varies from 14.4 dB to 20.3 dB according to the chosen frequency. In addition, the electrical subcarrier modulated by a Quadrature phase shift keying (QPSK) and a 16-quadrature amplitude modulation (QAM) signal at a data rate of 1 MSymb/s has been frequency up-converted up to 40 GHz with an error vector magnitude of 11.68% for the QPSK modulation and 10.94% for the 16-QAM.

UWB Doublet Generation Employing Cross-Phase Modulation in a Semiconductor Optical Amplifier Mach–Zehnder Interferometer

In this paper, a novel method to generate ultrawideband (UWB) doublets is proposed and experimentally demonstrated, which is based on exploiting the cross-phase modulation in a semiconductor optical amplifier (SOA). The key component is an integrated SOA Mach-Zehnder interferometer pumped with an optical carrier modulated by a Gaussian pulse. The transfer function of the nonlinear conversion process leads to the generation of UWB doublet pulses by tuning the SOA currents to different values.

Ultrafast All-Optical Signal Processing Using Optically Pumped QDSOA-Based Mach–Zehnder Interferometers

In this paper, we investigate the performance of all-optical logic circuits using quantum-dot semiconductor optical amplifier Mach-Zehnder interferometer (QDSOA-MZI) structures. For the first time, temporal changes in the linewidth enhancement factor (LEF) is analyzed under both optical and electrical pumping schemes using the nonlinear state space model (NSSM) for QDSOAs. We found that significant reduction in the LEF recovery time along with significant increasing in the LEF value of QDSOAs are two important factors that enhance the performance of optically pumped QDSOA-MZI-based all-optical logic gates. Simulation results show that optically pumped QDSOA-MZI structures can be used for implementation of all-optical logic circuits that can operate at bit rates higher than 160 Gb/s, which can never be reached using conventional electrical pumping schemes due to the long-phase recovery time in an electrically pumped QDSOAs. Furthermore, we study the effect of homogeneous broadening on the performance of all-optical logic gates. Moreover, dynamic response of a four-input all-optical XOR gate as a simple all-optical logic circuit is investigated and effect of cascading of optical gates on the performance of all-optical logic circuits is studied.

Performance evaluation of up-converted radio-over-fiber signal transmission based on SOA-MZI using different recovery schemes

The objective of this work is to implement differential phase shift keying (DPSK) encoded multiple data channels and local oscillator frequency over a common optical fiber with wavelength conversion using semiconductor optical amplifier Mach–Zehnder interferometer (SOA-MZI) and to recover the data signals by using different recovery schemes. The crosstalk penalties are kept at minimum value. One frequency up-converter is used in the system to reduce the complexity and cost of the system. An error free transmission of 1 Gbps differential phase-shift keying (DPSK) data at 2.5GHz to an optical radio frequency (RF) signal having the frequency of 30GHz is achieved through the designed system. The conversion efficiency at fRF+fIF is found to be maximum when the optical local oscillator power is approximately −2.5dBm. Further, the electric power has also been measured for the upconverted and downconverted signal which clearly indicates that crosstalk is not being imposed on the signals by SOA-MZI.

A special issue on High-Speed Optical Transmission and Processing

The rapid growth in network capacity and traffic rates raises the significance of high-speed optical transmission and processing. Recent progress in optical communication systems in relation to multiplexing technologies in different degrees of freedom, advanced multi-level modulation formats, coherent detection and digital signal processing has facilitated dramatic increases in transmission capacity. To be compatible with high-speed optical transmission, highspeed optical processing has gained increased interest to enable fast data manipulation in the optical domain and avoid cumbersome optical-electrical-optical conversions at network nodes. Recent progress in nonlinear-optical devices has led to enhanced efficiency, flexibility and functionality of ultrafast nonlinear-optical signal processing. It is expected that these advances in high-speed optical transmission and processing will pave the way to achieve superior performance of high-speed optical networks. It is our intention to bring the research community’s attention to these hot topics in optical communication systems and networks. In this “Special Issue on High-Speed Optical Transmission and Processing”, 8 review articles and 2 research articles focusing on relevant subjects by internationally active groups in the field are specially presented. In the review articles, Dr. Xiang Zhou at AT&T Labs—Research in USA reviewed the recent progress in transmission of 400 Gb/s wavelength-division multiplexing (WDM) channels for optical networks with standard 50 GHz grid. The enabling modulation, coding, line system technologies, and the existing challenges were discussed. Dr. Zhengxuan Li at Shanghai Jiao Tong University talked about the key technologies and system proposals of time and wavelength-division multiplexing passive optical networks (TWDM-PON). Dr. Thomas G. Brown at University of Rochester in USA presented light field manipulation in the spatial degree of freedom, showing fascinating effects in focusing, propagation, illumination, and imaging. Dr. Chaotan Sima at University of Southampton in UK summarized progress and recent developments of photonic Hilbert transforms. Dr. Claudio Porzi at the TeCIP Institute of Scuola Superiore Sant’Anna di Pisa in Italy reviewed on the use of semiconductor optical amplifier-Mach-Zehnder interferometer (SOA-MZI) for photonic add/drop and switching operations. Dr. Li Huo at Tsinghua University reported recent works in 100 Gb/s signal regeneration and processing. Dr. Wei Jin at the Hong Kong Polytechnic University discussed different types of air-silica photonic crystal fibers (PCFs) and their wide applications. Dr. Sigang Yang showed recent development of fiber optical parametric oscillators (FOPO) based on highly nonlinear dispersion-shifted fiber. In the research articles, Dr. Xia Guo at Beijing University of Technology targeted scalable light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) with tunnel-regenerated multi-active-region (TRMAR) structure. Dr. Muhammad Idrees Afridi at Beijing University of Posts and Telecommunications analyzed the impact of Rayleigh backscattering on single/dual feeder fiber wavelength-division multiplexing passive optical network (WDMPON) architectures. Overall, articles in this special issue cover the recent achievements of high-speed optical transmission and processing, particularly the latest emerging technologies and wide applications. We hope the readers will find them interesting and inspiring.

Review on SOA-MZI-based photonic add/drop and switching operations

Semiconductor optical amplifier-Mach-Zehnder interferometer (SOA-MZI) is a technologically mature optical device that can be exploited for a wide range of operations on both amplitude and phase modulated signals, with performance limited by the carrier lifetime in the SOAs. Recent advances on SOA structures have demonstrated their suitability for high quality, ultra-fast photonic signal processing, making SOA-MZI a good candidate for elaborating signals in new generation high-capacity optical networks. Dynamic wavelength switching/routing and add/drop operations are expected to bring benefits in future optical networks in terms of improved system flexibility and efficiency. The capability of performing such operations directly in the optical domain can significantly reduce the number of opto/electrical and electro/optical conversions in the routing nodes, reducing their power consumption and their latency time. Moreover, since phase-shift keying (PSK) formats or other advanced modulation formats involving both amplitude and phase modulation, start to coexist in optical communication systems with the conventional on-off keying (OOK) modulation format, the availability of a single device, suitable for processing all these different signals, is mandatory. The SOA-MZI fits all these requirements for both OOK and constant-envelope phase-modulated signals, providing a compact and flexible solution. Here we review on the use of the SOA-MZI for carrying out alloptical switching operations, by realizing wavelength conversion and add/drop functionalities, both for OOK and differential binary phase shift keying (DPSK) signals up to 40 Gb/s. Power penalties lower than 2 dB are demonstrated in all cases.

All-Optical Signal Regenerator for Differential Phase-Shift Keying Format Employing a Differential Encoding Circuit With SOA-MZIs

We propose and demonstrate the all-optical differential phase-shift keying (DPSK) signal regenerator with differential encoder employing a newly proposed all-optical T-type flip-flop (T-FF). The proposed configuration of an all-optical T-FF employs a counter-faced configuration of two semiconductor optical amplifier Mach–Zehnder interferometers (SOA-MZIs) to realize a short feedback path without loopback waveguide for high-speed operation. Numerical simulation reveals that it can operate as a T-FF at a bit-rate of 10-Gb/s under the condition of a carrier life time of 10 ps. We also experimentally demonstrate the operation of the proposed all-optical T-FF at a bit-rate of 2 Gb/s with a fiber-based experimental setup. Finally, we demonstrate the possibility of a DPSK signal regenerator with the combination of the proposed all-optical T-FF and the standard SOA-MZI by numerical simulations, which can drastically improve the quality of a DPSK signal degraded in transmission. We believe that the proposed configuration of an all-optical DPSK regenerator is promising for future optical networks.

All-Optical Switching of QPSK Signals for 100 G Coherent Systems

We propose a novel method for signal processing of phase-modulated signals suitable for 100 G coherent systems. By exploiting a single semiconductor optical amplifier Mach-Zehnder interferometer, all-optical selective switching with simultaneous wavelength conversion of bursts of data in the original signal is demonstrated. The operation is suitable for dynamic wavelength routing and/or add/drop operation in multichannel coherent systems, thus enabling flexible network resources optimization. The operation has been demonstrated for single-channel single-polarization, dual-channel (DC) single-polarization, and DC polarization-multiplexed (PM) 28 GBaud quadrature phase shift key-modulated signals. By exploiting coherent detection strategy and digital signal processing, an error rate below 10-3 prior to forward error correction has been observed for all the experiments; the corresponding optical signal-to-noise ratio penalty has been measured to be almost negligible in the single-polarization case whereas a maximum penalty below 1.5 dB for the PM one is reported.