Nonlinear Semiconductor Optical Amplifier Research Articles

Radio Frequency Generator Using Four Wave Mixing in Cascaded Nonlinear Semiconductor Optical Amplifiers

Radio Frequency Generator Using Four Wave Mixing in Cascaded Nonlinear Semiconductor Optical Amplifiers

Phase Regeneration of QPSK Signal in SOA Using Single-Stage, Wavelength Converting PSA

We demonstrate, for the first time, all-optical phase regeneration of a quaternary phase shift keying signal through phase sensitive amplification in nonlinear semiconductor optical amplifiers (SOAs), using a scheme only previously demonstrated in highly nonlinear fibre. We make use of a highly tunable phase quantizing scheme to circumvent some of the limitations imposed by the use of SOAs and show that it may function in either a conjugating or nonconjugating manner.

Experimental study on a low switching energy and high-linearity all-optical sampler based on terahertz optical asymmetric demultiplexer

We demonstrate experimentally a low switching energy and high-linearity all-optical sampler based on terahertz optical asymmetric demultiplexer (TOAD) composed of a nonlinear semiconductor optical amplifier (SOA) with a multiple quantum well structure. Effects of the sampling pulse power and asymmetric offset of SOA on the shape, width and amplitude of sampling windows are analyzed in detail respectively. It is found that the sampling pulse power has no effect on both the shape and the width of sampling windows, but has a significant effect on the window amplitude. Meanwhile there exists an optimal power which maximizes the sampled output and determines the switching energy of TOAD. The asymmetric offset of SOA from the center position in the loop determines the width of sampling windows and has great influences on both the shape and the amplitude of the sampling window. The sampling windows with different widths have approximately the same rise edge due to the fast response of SOA for the sampling pulse. However, the normalized amplitude of sampling windows firstly increases sharply with the increase of the asymmetry, then gradually flattens out, and tends to be stable in the end. In addition, the switching energy and linearity of TOAD are studied. The switching energy is as low as 25 fJ, and the linearity is as high as 0.99. Moreover, at different window widths, the switching energy of TOAD remains the same and the sampling windows have a very good linearity. However, the sensitivity of a TOAD sampler with different width is different: the wider the sampling window, the higher the sensitivity and the larger the corresponding dynamic range.

Optical Pulse Generation Based on an Optoelectronic Oscillator With Cascaded Nonlinear Semiconductor Optical Amplifiers

This paper presents a high-repetition-rate pulse train generator incorporating an optoelectronic oscillator based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). The optoelectronic oscillator is used to generate a high-stability microwave signal, by which an optical pulse train is generated using FWM effect in cascaded SOAs. The key feature of this work is that no external microwave signal source is needed for generating an optical pulse train. An optical pulse train with a repetition rate of 10 GHz and a pulsewidth of 19 ps is experimentally generated. The pulsewidth and the repetition rate can be tunable and are experimentally demonstrated.

Enhancing the Performance of Electro-Optical Heterodyne Receivers Using Gain Switched Photonic Local Oscillators

The performance of a Gain Switched (GS) optical source used as a Photonic Local Oscillator (PLO) in an Electro-Optical (EO) heterodyne receiver is experimentally evaluated and compared to the use of a traditional linearly modulated PLO. The EO heterodyne receiver used is based on an Ultra Nonlinear Semiconductor Optical Amplifier (XN-SOA) that provides a compact, cost effective and energy efficient receiver with a remote distribution of both PLO and Intermediate Frequency (IF) signals and a direct 50-ohms input for the Radiofrequency (RF) component. The comparison between both GS and linearly modulated PLO is made in terms of the conversion efficiency (conversion ratio); linearity (1-dB compression point) and noise (integrated RMS timing jitter). The analysis results in a significant improvement of the evaluated figures of merit when using a Gain Switched PLO.

Photonic Provisioning Using a Packaged SOI Hybrid All-Optical Wavelength Converter in a Meshed Optical Network Testbed

We demonstrate path wavelength routing and switching using a packaged and pigtailed hybrid integrated silicon-on-insulator (SOI) photonic circuit. The fabricated device incorporates a 1.25 mm nonlinear semiconductor optical amplifier mounted on the SOI board and two multimode interference-based cascaded delay interferometers monolithically integrated on the same SOI substrate. The photonic chip has a footprint of 384 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and performs all-optical wavelength conversion at ultrafast data rates. The packaged and pigtailed module is inserted and tested as a switching node in a meshed optical network testbed carrying real data traffic and encompassing a wavelength division multiplexing optical link. Optical path wavelength switching and routing is implemented by a generalized multiprotocol label switching control plane. We present 10 GbE video-streaming routing as well as 40 Gb/s wavelength switching employing the system integrated all-optical wavelength converter. Error-free transmission and different kind of end-to-end services (video distribution, audio conference, and video conference) have been successfully evaluated.

Quantum-Dash Mode-Locked Lasers for Tunable Wavelength Conversion on a 100 GHz Frequency Grid

All-optical wavelength converters play a key role for next-generation high-bit-rate optical networks. A high-speed, simple, and compact wavelength converter can resolve contention, reduce wavelength blocking, and enable a multitude of new wavelength routing approaches. We propose the combination of a quantum-dash mode-locked laser (QD-MLL) with a frequency-selective filter to provide (two) tunable wavelength pumps for wavelength conversion of optical channels in a dual-pump four-wave-mixing (FWM) scheme. Such a converter is simple, practical, and offers a wide conversion range, modulation format transparency, and the potential for photonic integration. We examine the performance of the proposed scheme experimentally with a QD-MLL and manually tunable optical filters. Wavelength conversion is achieved via an extremely non-linear semiconductor optical amplifier (SOA), a commercial SOA with very high FWM efficiency. We achieved near &#x2212;3&#x00A0;dB conversion efficiency across a 9.6&#x00A0;nm tuning range with a signal input power of &#x2212;3&#x00A0;dBm and a pump input power of 2&#x00A0;dBm. We performed bit error rate (BER) measurement on a 5.6&#x00A0;nm conversion range and obtained error-free transmission (BER &#x003C;10&#x2212;9) with less than 2&#x00A0;dB power penalty.

All-Optical Signal Processing by Using SOA Nonlinearities: Prospects for the Evolution of Next Generation of Optical Networks

This article focuses on the realization of all-optical signal processing functions based on the nonlinearities of a semiconductor optical amplifier (SOA) by reviewing the recent and significant patents and publications related to these new developments and applications. One of the main contributions of this paper is to highlight the feasibility of experimental implementation of three logic gates: NAND, OR, and NOR optical gates by exploiting the nonlinear polarization rotation in a SOA structure without changing the setup configuration. Switching between each optical function is done by only adjusting the input optical power level. The experimental investigation is done in free space, allowing optimum control and preservation of the polarization state of the injected and collected signals.

Semiconductor Optical Amplifiers in Coherent Optical-OFDM Systems

Experimental results of using a semiconductor optical amplifier (SOA) for amplification of a coherent optical-orthogonal frequency-division-multiplexing (CO-OFDM) transmission system are presented. The impact of the SOA nonlinearities on the amplification of a 10.94-Gb/s quadrature phase-shift keying CO-OFDM signal with respect to the input power, the signal wavelength, and the number of subcarriers is investigated.

All-optical frequency upconversion of a quasi optical single sideband signal utilizing a nonlinear semiconductor optical amplifier for radio-over-fiber applications

An all-optical frequency upconversion technique using a quasi optical single sideband (q-OSSB) signal in a nonlinear semiconductor optical amplifier (NSOA) for radio-over-fiber applications is proposed and experimentally demonstrated. An optical radio frequency signal (f(RF) = 37.5 GHz) in the form of a q-OSSB signal is generated by mixing an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) with an optical local oscillator signal (f(LO) = 35 GHz) utilizing coherent population oscillation and cross gain modulation effects in an NSOA. The phase noise, conversion efficiency, spurious free dynamic range (SFDR), and transmission characteristics of the q-OSSB signal are investigated.

Generation and Transmission of a Quasi-Optical Single Sideband Signal for Radio-Over-Fiber Systems

Generation of a quasi-optical single sideband (OSSB) signal for a radio-over-fiber system utilizing the coherent population oscillation effects in a nonlinear semiconductor optical amplifier and transmission over a single-mode fiber (SMF) are investigated. The quasi-OSSB signal generator consists of an electroabsorption modulator and a nonlinear semiconductor optical amplifier. Characteristics of generated quasi-OSSB signals having different radio-frequency (RF) waves (1-50 GHz) transmitted over SMFs of different lengths (4-21 km) were investigated. Bit-error-rate performance of quasi-OSSB signals having 155-Mb/s differential phase-shift keying (DPSK) data transmitted over 0- to 55-km-long SMFs was also evaluated.

Improvements to Long-Duration Low-Power Gain-Switching Diode Laser Pulses Using a Highly Nonlinear Optical Loop Mirror: Theory and Experiment

This work presents an experimental and theoretical study on the improvements to pulsed diode laser gain-switched (GS) optical sources. Simultaneous compression and reshaping of the limited quality pulses obtained with this technique are reported using a highly nonlinear optical loop mirror (HNOLM) directly coupled to the diode laser source, without any previous pulse conditioning. The HNOLM is based on the use of a microstructured optical fiber and a highly nonlinear semiconductor optical amplifier; it is compact and offers benefits in terms of reduced system complexity. The experimental observations are compared to a theoretical model of the system, and excellent agreement is observed.

A novel all optical method of implementing an n-bit wavelength encoded complete digital data comparator using nonlinear semiconductor optical amplifiers

Data comparator is the integral part of arithmetic and logical unit of any electronic or optical data processor. Due to some inherent limitations of electronics it cannot be possible to obtain a super fast operation (over terahertz limit) from electronic comparators. Again wavelength encoding technique has been established as an excellent one over other existing optical data encoding techniques. Semiconductor optical amplifier (SOA) technologies have shown their strong potentiality of realizing many all-optical systems. In this communication the authors have proposed a new scheme of developing all-optical wavelength encoded n bit binary comparator exploiting the four-wave mixing, wavelength filtering, wavelength conversion and nonlinear polarization rotation capabilities property of nonlinear semiconductor optical amplifiers. The scheme can be used for comparing signed and unsigned optical binary data of any bit wide numbers as well. The comparator is especially suitable for use as a building block in a larger optical circuit, such as in an all optical telecommunications switch.

Four-Wave-Mixing-Based Dual-Wavelength Conversion in a Semiconductor Optical Amplifier

The simultaneous wavelength conversion of two different formats or bit-rate optical signals, with low input power, is demonstrated in a highly nonlinear semiconductor optical amplifier with a single strong continuous-wave pump. For two amplitude-modulated signals of different bit rates, moderate penalties are obtained, and for the case of mixed amplitude and phase modulation at 10 Gb/s, practically penalty-free operation is achieved. In all cases, small difference (<; 1.1 dB) between single- and dual-channel operation is obtained, allowing asynchronous operation.

Experimental investigation on the quality improvement of low-power gain-switching diode laser picosecond pulses using a compact highly nonlinear optical loop mirror

The experimental work presented in this paper investigates the quality improvement of gain-switched (GS) sources. GS is a straightforward technique to achieve short pulses from diode lasers; however, such pulses exhibit long duration (10-100 ps), low power (in the milliwatt range), are asymmetric and are often generated along with pedestals or subpulses. Simultaneous compression and reshaping of these low quality pulses has been observed experimentally for several input power values. These effects have been achieved using a highly nonlinear optical-loop mirror, based on a microstructured optical fiber and a nonlinear semiconductor optical amplifier. It is designed to be compact and to directly process these complex pulses thus eliminating the requirement for prepulse conditioning. This offers overall benefits in terms of reduced system complexity. The quality of the pulses is characterized by their temporal width, pedestal height, duration, and spectral components. A maximum overall compression factor of 6 for a 10-mW average input power is observed. Additionally, the pulses obtained are observed to have improved quality for the input power range considered (500 µW to 30 mW, GS typical operational range) and the experimental scheme used preserves the compactness, efficiency, and simplicity of GS light sources.

Method of developing an all optical wavelength encoded single bit comparator exploiting four wave mixing and wavelength filtering character of nonlinear semiconductor optical amplifiers

Data Comparator is the integral part of arithmetic and logical unit of any electronic or optical data processor. Due to some inherent limitations of electronics it is not possible to obtain super fast data processing (over Terahertz limit) from electronic comparator. Again frequency encoding technique has been established as an excellent one over the other optical data encoding techniques. Semiconductor optical amplifiers (SOA) technologies have shown its potentiality of realising many all-optical systems. In this communication the authors have proposed a new all-optical wavelength encoded single bit binary comparator exploiting the four wave mixing and wavelength filtering property of nonlinear semiconductor optical amplifier.

Compression and Reshaping of Gain-Switching Low-Quality Pulses Using a Highly Nonlinear Optical Loop Mirror

This work presents an experimental study on the improvement of pulsed diode laser gain-switched (GS) optical sources where simultaneous compression and reshaping of the low-quality pulses obtained with this technique are reported. These effects are achieved using a highly nonlinear optical loop mirror (HNOLM) directly coupled to the diode laser source without any previous pulse conditioning. The HNOLM is based on the use of a microstructured optical fiber and a highly nonlinear semiconductor optical amplifier. This system is compact and robust. The pulses have been characterized through the evaluation of their autocorrelation traces and a study using a temporal information via intensity algorithm. Results show that the loop improves the quality of complex GS pulses in several aspects: they are compressed, their symmetry is improved, and the width and height of the pedestals that commonly appear accompanying GS pulses are reduced. The system proposed offers overall benefits in terms of reduced system complexity.

Multiple-channel optical signal processing with wavelength-waveform conversions, pulsewidth tunability, and signal regeneration

A multiple-channel multiple-function optical signal processor (MCMF-OSP) including wavelength-waveform conversions, pulsewidth tunability, and signal regeneration is realized through AND logic gate based on optical parametric processing with a pulsewidth-tunable RZ clock pump. The proposed scheme simultaneously offers four signal processing functions which are useful in wavelength-division multiplexing (WDM) transmission systems, and at network nodes with the necessity for multiple-channel data processing. After the discussions on the concept of MCMF-OSP, a proof-of concept experiment is demonstrated on four 10 Gb/s nonreturn-to-zero (NRZ) data format channels using nonlinearities in semiconductor optical amplifier (SOA) and highly nonlinear fiber (HNLF). A wavelength and waveform conversions to return-to-zero (RZ) modulation format are obtained together with pulsewidth-tunable range from 20% to 80% duty cycles for all input signals. The converted signals inherit the timing and waveform of the RZ clock pump, thus resulting in a time regeneration and large tolerance to narrow-band optical filtering (NAOF) and fiber accumulated chromatic dispersion (CD).

SOA Intensity Noise Suppression in Spectrum Sliced Systems: A Multicanonical Monte Carlo Simulator of Extremely Low BER

We present a thorough numerical study of intensity noise mitigation of spectrum sliced wavelength-division multiplexing (SS-WDM) systems employing a nonlinear semiconductor optical amplifier (SOA) before the modulator. Our simulator of the SS-WDM link, embedded inside a Multicanonical Monte Carlo (MMC) platform, estimates the tails of the probability density functions of the received signals down to probabilities smaller than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-16</sup> . We introduce a new, simple, and efficient technique to handle intersymbol interference (ISI) in MMC simulations. We address the impact of optical postfiltering on SOA noise suppression performance. While previous research experimentally observed the SOA-induced noise cleaning in SS-WDM systems, this is the first complete simulator able to correctly predict the ensuing BER improvement. We measure the BER at different bit-rates and validate predicted BERs with and without post filtering.

Method of implementing frequency encoded multiplexer and demultiplexer systems using nonlinear semiconductor optical amplifiers

Multiplexing and demultiplexing are the essential parts of any communication network. In case of optical multiplexing and demultiplexing the coding of the data as well as the coding of control signals are most important issues. Many encoding/decoding mechanisms have already been developed in optical communication technology. Recently frequency encoding technique has drawn some special interest to the scientific communities. The advantage of frequency encoding technique over any other techniques is that as the frequency is fundamental character of any signal so it remains unaltered in reflection, refraction, absorption, etc. during transmission of the signal and therefore the system will execute the operation with reliability. On the other hand, the switching speed of semiconductor optical amplifiers (SOA) is sufficiently high with property of best on/off contrast ratio. In our present communication we propose a method of implementing a ‘4-to-1’ multiplexer (MUX) and a ‘1-to-4’ demultiplexer (DEMUX) exploiting the switching character of nonlinear SOA with the use of frequency encoded control signals. To implement the ‘4-to-1’ MUX and ‘1-to-4’ DEMUX system, the frequency selection by multiquantum well (MQW)-grating filter-based SOA has been used for frequency routing purpose. At the same time, the polarization rotation character of SOA has also been exploited to get the desired purpose. Here the fast switching action of SOA with reliable frequency encoded control input signals, it is possible to achieve a faithful MUX/DEMUX service at tera-Hz operational speed.