Characteristics Of Semiconductor Optical Amplifier Research Articles

High-speed signal processing and wide band optical semiconductor amplifier in the optical communication systems

Abstract This work clarifies the analysis of the theoretical study of noise and transmission gain characteristics of semiconductor optical amplifiers (SOAs), which are relevant in the novel local area optical communication systems. We investigated the effects of noise on AlGaAs/GaAs SOA transmission performance through the measurement of output power, optical gain, the optical signal-to-noise ratio, and noise figure. It was observed that noise has a dramatic effect on SOAs’ operation transmission efficiency, and the performance of the amplifier structure may be limited. If the drive current and injection power at the SOA can be changed and its active region length modified, then the variation of gain, optical signal-to-noise ratio, and noise figure at the output of the structure can be obtained.

Optical scheme of developing Hamming code-based error detection and correction using Toffoli gates with frequency encoded data

Bit-error detection and correction is a very important part of a data communication network. In this article, we propose an optical approach to designing an error detection and correction circuit using Hamming code-based frequency encoded binary data and Toffoli gates. Here, the Toffoli gates are made of semiconductor optical amplifiers (SOAs) that work based on the nonlinear polarization rotation property. The characteristics of SOA, including very fast switching action (about 0.01 ns), low power consumption, frequency independent cross-polarization gain in the C-band, cascading property, etc., make the scheme attractive. The frequency encoded data-based proposed scheme will be effective for WDM communication networks. MATLAB simulation results testify to the feasibility of the proposed scheme.

DATA ANALYSIS WHEN CREATING AN EXTENDED GIGABIT OPTICAL NETWORK

The article describes the application of data analysis, which allows, based on the processed experimental data, to obtain new knowledge about the behavior and capabilities of a gigabit passive optical network (GPON network). The description of the test bench of the GPON network is given. The paper studied the characteristics of semiconductor optical amplifiers used to increase the range of GPON networks, as well as their dependence on the input power and signal wavelength. For data processing, the MatLab mathematical calculation automation package and the OriginLab package for numerical data analysis and scientific graphics were used. It is shown that the use of an EDFA amplifier (an optical amplifier on an erbium-doped fiber) in the architecture of a gigabit passive optical network is the best choice and allows expanding the range of the GPON network from 20 kilometers to 60 kilometers.

Nonlinear Characteristics of Semiconductor Optical Amplifiers for Optical Switching Control Realization of Logic Gates

Abstract This paper studies the problem of data access at the receiver with large bit error rate and low quality factor. Due to this issue the information got inaccurately at the receiver side, the data should have high quality factor and low bit error rate to be simple of identification at the receiver when using the gates. The nonlinear properties of the semiconductor optical amplifier are utilized to accomplish the Boolean variable based math work, in which AND, NAND, and OR gates potentially used to endorse the Boolean function. Through blend this gates together any Boolean function can be accomplished and utilized to perform optical signal processing. The quality factor and BER are measured by utilizing the eye diagram analyzer, the state of the output bit and also shaped by the oscilloscope visualizer in optiwave simulation program. These models can be used for wavelength converter, header recognition, parity checking, binary addition, packet-header modification, encoding and encryption with pattern matching, and data encryption with high speed and high quality factor.

Design of optical quaternary adder and subtractor using polarization switching

The replacement of binary logic with the multi-valued logic based (MVL) system in the optical domain might be the way to fulfill the demand of faster data computing with a huge amount of data handling capability. Quaternary logic is one of the most promising MVL. In this article, the authors have proposed a new method of developing optical adder and subtractor based on quaternary logic. The frequency encoding technique is used here for data representation because of its inherent property of constancy during reflection, refraction, and transmission. So that, instead of any fluctuation in intensity, different bits can be processed or communicated without any error and thus, the bit error rate can be minimized which makes the scheme novel one. Polarization switching characteristics of semiconductor optical amplifier are adopted here to develop these basic units. The simulative studies on PSW clarify the optical switching mechanism of it. The optical circuits of quaternary adder and subtractor are also testified with simulation results for different cases and thus the admissibility of the proposed scheme is enhanced.

Realization of High Speed All-Optical Logic Gates based on the Nonlinear Characteristics of a SOA

Objectives: In this paper the method to overcome the bit rate limitations caused by dual conversion of the signal has been examined. Taking this phenomenon as base for this paper, a novel and potentially integrable circuit design is proposed for the realization of all-optical logic gates based on non-linear properties of SOA. Methods/Statistical Analysis: For this purpose a relatively new method to achieve larger transmission capacity and longer transmission distance with high data rates by employing many logic XOR, AND, OR, NOT gates based on non-linear characteristics of Semiconductor Optical Amplifier (SOA) in optical communication systems is used. Findings: This is done by eliminating the need of optoelectronics conversions and therefore the data remains in the optical domain. This XOR, AND, OR and NOT gate can be executed on 60 gigabits per second on any bit sequence in order to achieve such a high data rate. Application/Improvement: Its application includes Agile radar aircraft antenna system, control of electronic automatic RF attenuator, Automotive courtesy light etc.

Investigation of characteristics of semiconductor optical amplifiers as a multifunctional device for radio-over-fiber systems

The paper discusses options for using semiconductor optical amplifiers in the radio-over-fiber systems. A theoretical evaluation of parameters of the optical amplifier, modulator and detector implemented on the basis of a semiconductor optical amplifier is made. Parameters of a multifunctional optical amplifier-modulator-detector based on the semiconductor optical amplifier are also estimated.

WITHDRAWN: Numerical simulation and experimental study on the gain modulation characteristics of semiconductor optical amplifier induced by injected optical signals

WITHDRAWN: Numerical simulation and experimental study on the gain modulation characteristics of semiconductor optical amplifier induced by injected optical signals

Analysis of ultrafast nonlinear phenomena’s influences on output optical pulses and four-wave mixing characteristics in semiconductor optical amplifiers

We have analysed the output pulse characteristics of semiconductor optical amplifier (SOA). It is shown that they can be modified due to the variation of input parameters, such as, gain, input pulsewidth, input pulse energy and effects imposed by the medium. Therefore, the influence of these parameters are analysed on the output pulse shape, spectrum, chirp and pulsewidth. We have used the nonlinear propagation equation taking into account the gain spectrum dynamics, gain saturation which depends on carrier depletion, carrier heating, spectral hole-burning, group velocity dispersion, self-phase modulation and two photon absorption. We have used the finite-difference beam propagation method to simulate the wave evolution both in time and spectral domain in the SOA. We have also simulated the four-wave mixing characteristics between pulses for various input pulses. An accurate output pulse shape can be achieved by controlling the mentioned parameters. To the authors knowledge, pulse shaping in co-propagation regime due to medium effect and input pulse shapes in presence of all nonlinear effects relevant to picosecond regime have been studied comprehensively, for the first time in this work.

Wavelength reused bidirectional transmission of adaptively modulated optical OFDM signals in WDM-PONs incorporating SOA and RSOA intensity modulators

Detailed numerical investigations are undertaken of wavelength reused bidirectional transmission of adaptively modulated optical OFDM (AMOOFDM) signals over a single SMF in a colorless WDM-PON incorporating a semiconductor optical amplifier (SOA) intensity modulator and a reflective SOA (RSOA) intensity modulator in the optical line termination and optical network unit, respectively. A comprehensive theoretical model describing the performance of such network scenarios is, for the first time, developed, taking into account dynamic optical characteristics of SOA and RSOA intensity modulators as well as the effects of Rayleigh backscattering (RB) and residual downstream signal-induced crosstalk. The developed model is rigorously verified experimentally in RSOA-based real-time end-to-end OOFDM systems at 7.5 Gb/s. It is shown that the RB noise and crosstalk effects are dominant factors limiting the maximum achievable downstream and upstream transmission performance. Under optimum SOA and RSOA operating conditions as well as practical downstream and upstream optical launch powers, 10 Gb/s downstream and 6 Gb/s upstream over 40 km SMF transmissions of conventional double sideband AMOOFDM signals are feasible without utilizing in-line optical amplification and chromatic dispersion compensation. In particular, the aforementioned transmission performance can be improved to 23 Gb/s downstream and 8 Gb/s upstream over 40 km SMFs when single sideband subcarrier modulation is adopted in the downstream systems.

Effect of absorption loss on the saturation characteristics of semiconductor optical amplifier

Semiconductor optical amplifiers (SOAs) as nonlinear devices always work in the gain saturation region. Therefore, the saturation gain is an important parameter of SOAs. However, the existing theoretical gain formula greatly deviates from the experimental measurements. We find experimentally that the effect of the absorption loss on the SOA gain cannot be neglected, especially when the SOA is biased into the saturation region. In this paper, considering the influence of the absorption loss, we propose a modification to the SOA gain formula in common use. We are able to validate the revised formula against the experimental measurements. Thus the theoretical formula after modification can be accurately applied to evaluate the SOA gain in practice.

Evaluating characteristics of semiconductor optical amplifiers using optical pumping near the transparency

The improved characteristics of semiconductor optical amplifiers (SOAs) with optical pumping near the transparency (OPNT) are evaluated, and its improving mechanisms are analyzed. The characteristics of saturation behaviors, noise figures, signal-to-noise ratio, and gain recovery time are greatly improved by OPNT, especially for the counterpropagating scheme. The impacts of different wavelengths of a holding beam from absorption to the gain region are investigated contrastively. The maximum value of the small signal gain recovery time is obtained at the transparency wavelength. Also, the quality of the output eye patterns of a cross-gain modulation (XGM) system has been greatly improved by using OPNT, especially for the signal beyond 10 Gbit/s.

Analysis on dynamic characteristics of semiconductor optical amplifiers with certain facet reflection based on detailed wideband model

Dynamic characteristics of semiconductor optical amplifiers (SOAs) with certain facet reflection in different operation conditions are theoretically investigated with a detailed wideband model. Influences of different facets reflectivities are numerically simulated for different lengths of active regions. The results indicate that the gain recovery time can be reduced to 50% of the initial value while the other related characteristics are optimized for appropriate facets reflections. A half reflective semiconductor optical amplifier (HR-SOA) with a cleaved facet on rear facet and an antireflection coating on front facet can speed up the gain recovery with easy realization and low cost. The related characteristics of this structure are evaluated. It's also indicated that the gain recovery has further potential to be reduced as low as twenties picoseconds for a long active region.

Realization of All-Optical XOR, NOR, and NAND Gates in Single Format by Using Semiconductor Optical Amplifiers

By using the cross gain modulation (XGM) characteristics of semiconductor optical amplifiers (SOAs), multi-functional all-optical logic gates including XOR, NOR, and NAND gates are successfully demonstrated at 10 Gbps in single format. Numerical simulation is also performed by using the transmission-line laser model (TLLM), which is confirmed by using three SOAs experimentally. These combined all-optical multi-functional logic gates will provide more complex and complicated all-optical logic operations.

반도체 광증폭기를 이용한 다기능 전광 논리 소자의 설계 및 측정

반도체 광증폭기에 기반을 둔 이득포화특성을 이용하여 XOR, AND, OR 논리 게이트를 동시에 구현하는 다기능 전광 논리소자를 설계하고 구현하였다. 상용화된 프로그램인 VPI Component <TEX>$Maker^{TM}$</TEX>을 사용하여 시뮬레이션을 수행하였고 10 Gbit/s의 입력 신호를 사용하여 XOR, AND, OR 논리동작을 동시에 구현하는 다기능 전광 논리소자를 구현하였다. Using the cross-gain modulation (XGM) characteristics of semiconductor optical amplifiers (SOAs), multi-functional all-optical logic gates, including XOR, AND, and OR gates are successfully simulated and demonstrated at 10Gbit/s. A VPI component maker^TM simulation tool is used for the simulation of multi-functional all-optical logic gates and the10 Cbit/s input signal is made by a mode-locked fiber ring laser. A multi-quantum well (MQW) SOA is used for the simulation and demonstration of the all-optical logic system. Our suggested system is composed of three MQW SOAs, SOA-1 and SOA-2 for XOR logic operation and SOA-2 and SOA-3 for AND logic operation. By the addition of two output signals XOR and AND, all-optical OR logic can be obtained.

All-optical half adder using cross gain modulation in semiconductor optical amplifiers

By using the gain nonlinearity characteristics of semiconductor optical amplifier, an all-optical binary half adder at 10 Gbps is demonstrated. The half adder operates in a single mechanism, which is cross gain modulation. The half adder utilizes two logic functions of SUM and CARRY, which can be demonstrated by using XOR and AND gates, respectively. The extinction ratios of both XOR and AND gates are about 6.1 dB. By achieving this experiment, we also explored the possibilities for the enhanced complex logic operation and higher chances for multiple logic integration.

Theoretical study on ultrafast response of semiconductor optical amplifier

We proposed a novel method to analyze the propagation of sub-picosecond optical pulses through semiconductor optical amplifiers(SOA), fully considering spectral dispersion of ultrashort pulses. A reasonable model is established via sampling the pulses simultaneously in time domain and frequency domain. Based on the established model, we observed an evident shift of the pulse spectrum, which agrees well with the experiment results in literature. Further, the relationship is discussed respectively between the value of shift and several external conditions, including wavelength, energy, width of the pulse, length of SOA and injected current. Gain suppression induced by ultrafast nonlinearities including carrier heating, spectral hole burning and two-photon absorption is described in detail, employing two-beam configuration. The simulated results give good guidance to the improvement of ultrafast dynamic characteristics of SOAs.

Improvement of Power Margin in 10-Gb/s SOA-Boosted Transmission Systems Using Phase-Modulated Duobinary Modulation Formats

We theoretically investigate the performance of 10-Gb/s semiconductor optical amplifier (SOA)-boosted transmission systems using the nonreturn-to-zero (NRZ), conventional duobinary, and phase-modulated (PM)-duobinary modulation formats. NRZ and conventional duobinary modulation formats are based on the intensity modulation. When the NRZ and conventional duobinary modulation formats are used, the nonlinear characteristics of SOA severely distort the signals. On the other hand, the PM-duobinary modulation format is based on differential binary phase-shift-keying modulation. When the PM-duobinary modulation format is employed, the nonlinear characteristics of SOA scarcely affect the signals which maintain a constant intensity in SOAs. Using the PM-duobinary modulation format, we can significantly improve the power margin in SOA-boosted transmission systems.

Mitigation of dispersion-induced effects using SOA in analog optical transmission

A novel technique to improve an analog optical transmission performance by reducing both the nonlinearity and chromatic dispersion induced carrier suppression has been proposed. The intrinsic nonlinear distortion component of Mach-Zehnder modulator (MZM) was reduced by gain saturation characteristics of semiconductor optical amplifier (SOA). The composite triple beat (CTB) of MZM was reduced as much as 9 dB at the quadratic bias point and the following enhancement of dynamic range by 4.5 dB was obtained. The RF carrier suppression for the transmission length and operating frequency was reduced by a negative chirp characteristic of semiconductor optical amplifier (SOA) and the enhancement of CTB after transmission were also achieved as a result of the linearization using SOA.

Theoretical study of frequency chirping and extinction ratio of wavelength-converted optical signals by XGM and XPM using SOA's

We develop a complete large-signal dynamic model of semiconductor optical amplifier (SOA)-based wavelength converters using cross-gain modulation (XGM) and cross-phase modulation (XPM). The large-signal dynamic model has been implemented using the modified transfer matrix method (TMM). This model takes into account longitudinal variations of carrier-induced refractive index, n-parameter, internal reflection, photon density, and amplified spontaneous emission noise at each small section. Therefore, we can accurately estimate frequency chirping, optical pulse patterns, and the extinction ratio as well as the dynamic characteristics of SOA's. Frequency chirping and the extinction ratio have been calculated for various parameters such as signal power and wavelength, CW power and wavelength, and facet reflectivity. Modulation bandwidth, defined by the 3-dB drop as the eye opening ratio (EOR) is investigated with current density, confinement factor, and cavity length.